In this article, we will explain why you would want to wire lithium-ion batteries in parallel, how you wire them in series and how to charge battery cells while in series.

How To Wire Lithium Batteries In Parallel 

So, can lithium batteries be wired in parallel? Lithium-ion batteries are one of the most ubiquitous pieces of technology on the planet. You can find them all over the place. They are on the roads, on our desks, and in our pockets. In fact, the world as we know it could not exist without lithium-ion batteries.&nbsp;Wiring lithium-ion batteries in parallel is simple. All you have to do is connect all the + connections together and all of the - connections together. A lithium-ion battery of any voltage level can be composed of single cells in series. More often than not, however, lithium-ion cells are wired in parallel Some configurations will require just 2 cells in parallel, while other configurations can require 7 or more. Either way, once you wire a set of lithium-ion batteries in parallel, they function as one single cell on an electrical level.&nbsp;In this article, we will discuss whether or not lithium-ion batteries can be wired in parallel. We will also discuss the importance of lithium-ion parallel connections. After that, we will shed some light on the charging process for lithium-ion batteries connected in parallel and if it differs from charging a single lithium-ion battery. Finally, we will discuss balancing lithium-ion battery cells in parallel.&nbsp;<h3>Single Cell Lithium Ion Capacity Limits</h3>Lithium-ion batteries are extremely power dense and over the last 10 years, the cost of a given amount of lithium-ion energy has come down 10-fold. There is, however, a major shortcoming when it comes to lithium-ion battery cells. The capacity of a single cell is quite low. At the time of this writing, a single cell or series chain of 18650 cells will have a maximum capacity of about 3600ma. When it comes to 21700 cells, this figure is about 5000ma.&nbsp;While it’s true there are many products and peripherals that can chug right along sipping merely milliamps of current, this is not the case for most consumer devices. Most things are going to draw an amp or two, or even considerably higher.For example, you can technically run a 12V inverter on just 3 lithium-ion cells in series. But really, how long would it run? Let’s say you have three 5000mah cells in series. This would create a battery with a nominal voltage of 11.1 volts and a capacity of 5ah. A 12V inverter will run at that voltage more or less just as well as it would at 12 volts.This is especially true considering the full charged voltage of a 3S lithium-ion battery pack is 12.6 volts. But the question still remains: How long could such a small battery run an inverter?&nbsp;Let’s say we are running a TV that consumes 120W watts of energy per hour. A nominal voltage of 11.1 multiplied by a cell capacity of 5 amp hours equals 55.5 watt hours of energy.&nbsp;11.1V x 5Ah = 55.5WhTo estimate how long something will run on a given battery, all you have to do is divide the number of watt hours available in the battery pack by the number of watts per hour your load uses.&nbsp;55Wh / 120W = 0.4625 hours (27.75 minutes)It is important to consider, however, that no system is 100 percent efficient. Most inverters are about 90% efficient. So, if your TV requires 120 watts to run, the inverter will have to draw about 132 watts from the battery. &nbsp;55Wh / 132W = 0.4167 hours (25 minutes)NOTE: 3 lithium-ion cells in series produce a battery that has a fully charged voltage of 12.6 volts and a dead voltage of around 8.9 volts. Most inverters stop working at around the 10.5 volt mark, so you will really only get about 30Wh of usable energy out of 3 lithium-ion cells when they are being used to power an inverter.&nbsp;30Wh / 132W = 0.2273 hours (13 minutes)It’s clear to see that single lithium-ion cells, while very impressive, don’t have enough capacity to run most consumer electronics for any reasonable amount of time. So then, of course, the question comes to: ‘How do you increase the capacity of lithium-ion battery cells?’&nbsp;<h3>Can Lithium Batteries Be Wired In Parallel?</h3>Yes. Not only can lithium-ion batteries be wired in parallel, a lot of the time it's necessary to do so. Before we get into how to do it, first let's explain why you would want to wire lithium-ion batteries in parallel in the first place.&nbsp;<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;parallel2.jpg&quot;,&quot;filesize&quot;:301919,&quot;height&quot;:780,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/H7AcFj3gmBxdCzU7v5aNKVEUhjAYG13axVpAxLmg.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/H7AcFj3gmBxdCzU7v5aNKVEUhjAYG13axVpAxLmg.jpg&quot;,&quot;width&quot;:1040}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/H7AcFj3gmBxdCzU7v5aNKVEUhjAYG13axVpAxLmg.jpg"><img src="https://admin.cellsaviors.com/storage/H7AcFj3gmBxdCzU7v5aNKVEUhjAYG13axVpAxLmg.jpg" width="1040" height="780"><figcaption class="attachment__caption">parallel2.jpg 294.84 KB</figcaption></a></figure><h3>Lithium Ion Parallel Connections</h3>So, can lithium-ion batteries be wired in parallel? Aboslutely! Lithium-ion battery cells can be configured in just about any parallel or series configurations that you can think of. If you plan on building high-quality lithium-ion battery packs, then the importance of having a clear understanding of lithium-ion parallel connections cannot be understated.&nbsp;Wiring lithium-ion batteries in parallel is simple. All you have to do is connect all of the - connections to each other and all the + connections to each other.&nbsp;Lithium Ion Batteries Wired In Parallel - Capacity4.2 volts x 1 = 4.2 volts3 amp hours + 3 amp hours = 6 amp hoursWhen lithium-ion batteries are wired in parallel, their capacities add together but their voltages do not. Their capacities, however, are not the only thing added together when lithium-ion batteries are wired in parallel. Their current carrying capacity (Ampacity) is also added together. So, assuming each cell can handle 10 amps of current: Lithium Ion Batteries Wired In Parallel - Ampacity4.2 volts x 1 = 4.2 volts10 amps + 10&nbsp; amps = 20 amp<h3>Can You Charge 2 Lithium Batteries Connected In Parallel?&nbsp;</h3>Yes, you can charge 2 or more lithium batteries that are connected in parallel. Before you connect them in parallel, however, it's very important that you charge each battery separately (but with the same charger) to ensure that they are both at the same voltage level before they are attached in parallel.&nbsp;After that, the lithium-ion batteries wired in parallel can be charged as if they were a single cell.&nbsp;<h3>How To Charge Lithium Batteries Connected In Parallel?&nbsp;</h3>The procedure for charging multiple lithium-ion battery packs in parallel is exactly the same as charging them separately. Again, it's just important to make sure that the lithium batteries are balanced before they are connected together.&nbsp;<h3>How Do You Balance Lithium Batteries In Parallel?&nbsp;</h3>Once lithium-ion batteries are connected in parallel, they will balance themselves. This process, however, can be both dangerous and slow. If the cells are not balanced before connecting them, then there will be a substantial voltage difference between cells which will cause an unknown (and possibly massive) amount of current to flow between the higher and lower voltage cells.&nbsp;In contrast, if you get the cells very close in voltage and then rely on the internal self-balancing to do the rest, it will take a very long time before they all completely equalize. The good news is that once they are connected in parallel, this process happens continuously and on its own.&nbsp;<h3>Conclusion</h3>That was quite a bit of information. So, let's do a quick review of everything that we have covered. Can lithium batteries be wired in parallel? Yes, and in most cases, they have to be. Can you charge 2 lithium batteries connected In parallel? Yes, of course. It would be inconvenient to have to break down your battery pack to charge it, wouldn't it?&nbsp;When it comes to charging lithium batteries connected in parallel, it’s no different than charging a lithium-ion battery on its own. It will, of course, take longer to charge, but at the same time, it would be able to handle higher charging currents as well. &nbsp;We hope this article helped you learn more about how to wire lithium-ion batteries in parallel. Thanks for reading!

In this article, we will explain why you would want to wire lithium-ion batteries in series, how you wire them in series and how to charge battery cells while in series.

How To Wire Lithium Batteries In Series

If you are wondering how to wire lithium batteries in series, then this is the article for you. Lithium-ion batteries have become part of everyday life. They are all around us, in our phones, tablets, laptops, electronic cigarettes, cars, and just about any other portable device you can think of.&nbsp;Wiring lithium-ion batteries in series is simple. All you have to do is connect the + connection of the first cell to the - connection of the next cell. Some configurations will require just 3 cells in series, other configurations require 20 or more. Either way, once you wire a set of lithium-ion batteries in series, it will form an open-ended chain. At the ends of the chain, you will find your main - and + connections.&nbsp;In this article, we will explain why you would want to wire lithium-ion batteries in series. We will also explain if it's even possible and if the battery cells can be charged while in series.&nbsp;<h3>Lithium Ion Voltage Woes&nbsp;</h3>Lithium-ion batteries are extremely power dense and over the last 10 years, the cost of a given amount of lithium-ion energy has come down about 10-fold. There is, however, a major shortcoming when it comes to lithium-ion battery cells. The voltage of a single lithium-ion battery is quite low. A single cell or parallel group of cells has a maximum voltage of just 4.2 volts. This is not a high enough voltage to power most things.&nbsp;For example, most inverters need at least 11 volts to turn on, and 12 or 13 to operate efficiently. Single LEDs can run at single-cell lithium-ion voltages, but if you plan on running a more sophisticated lighting setup, you are going to need a higher voltage. Most motors will work at just about any voltage you give them, but if you give a motor the voltage from a single lithium-ion cell, it will spin very, very slowly.&nbsp;So then, of course, the question comes to: ‘How do you increase the voltage of a lithium-ion battery?’ If you want to start effectively using lithium-ion batteries at reasonable voltage levels and have them power the vast majority of electrical devices that require a voltage level higher than that which a single lithium-ion cell can provide, you will first have to learn a little bit about series and parallel electrical connections in general.&nbsp;<h3>What's The Difference Between Series And Parallel?</h3>When two power sources are wired in parallel, their voltages are not added but their amps (current carrying capacity) are. In contrast, when two power sources are wired in series, their voltages are added but their amps do not combine.&nbsp;Below we have an example of what would happen if you wire 2 power sources in series and in parallel. In this example, the two power supplies are both 12 volts and can carry 4 amps.&nbsp; Series12 volts + 12 volts = 24 volts4 amps x 1 = 4 amps&nbsp; Parallel12 volts * 1 = 12 volts4 amp + 4 amps = 8 ampsAs you can see, when power sources are in series, the voltages add together but the amps do not. In contrast, when power sources are in parallel, the amps are added together and the voltages are not.&nbsp;NOTE: Adding the current carrying capacity does NOT mean that the new combined power supply will send that much current through the load. This is a common misconception. What it actually means is that the combined power supplies can handle UP TO that much current.<h3>Lithium Ion Series Connections</h3>So, can lithium-ion batteries be wired in series? Yes! Lithium-ion battery cells can be put into an infinite number of series and parallel configurations to achieve just about any end result you can imagine. Understanding the difference between series and parallel battery connections is crucial to building reliable, safe, high-performance lithium-ion battery packs.&nbsp;We can provide a similar example to the one above, except this time we will use battery cells instead of power supplies:&nbsp;When two lithium-ion batteries are wired in parallel, their voltages are not added but their amp hours are. As you would expect, when lithium-ion batteries are wired in series, their voltages are added but their amp hours are not.&nbsp; Lithium Ion Batteries Wired In Series4.2 volts + 4.2 volts = 8.4 volts3 amp hours * 1 = 3 amp hours Lithium Ion Batteries Wired In Parallel4.2 volts *1 = 4.2 volts3 amp hours +&nbsp; 3 amp hours = 6 amp hoursSo, it works the same for lithium-ion batteries. When lithium-ion battery cells are wired in series, the voltages add together but the amp hours do not. Then, just like with the power supplies, when lithium-ion batteries are wired in parallel, the amp hours are added together but the voltages are not.&nbsp;NOTE: You may have noticed that we mentioned amps when talking about the power supplies and mentioned amp hours when talking about the batteries. It's important to take into consideration that lithium-ion battery cells have both an ‘amps’ rating and an ‘amp hours’ rating.&nbsp;‘Amps’ refers to how much current something can handle. ‘Amp hours’ refers to how long something can provide a given level of current.&nbsp;The power supplies are plugged into the wall, so they don't have any time-related ratings. Just remember that the same thing applies to lithium-ion cells. If you have a cell that can handle a current of 10 amps, if you put those cells in series, they can still only handle 10 amps. If you put them in parallel, however, their current carrying capacity is added.&nbsp;Also, while it may be true that adding two 10A cells in series does not increase the amount of amps that they can provide, it does increase the amount of watts (overall amount of power). I will explain:If you have two 4.2 lithium batteries in series, you end up with a power source that can handle 10 amps at 8.4 volts. 10 amps times 8.4 volts is 84 watts.That same cell on its own would only be able to handle 10 amps at 4.2&nbsp; volts.10 amps times 4.2 volts is 42 watts.<h3>How Do You Wire Lithium Batteries In Series?</h3>So, you have a good supply of high-quality lithium-ion battery cells and you understand why they need to be wired in series. So now it's time for the next question: How do you wire multiple lithium-ion batteries in series?’ The good news is wiring lithium-ion batteries in series is no different than wiring any other type of battery in series.To wire lithium-ion batteries in series, you have to attach the + connection of one cell to the - connection of the next cell. Regardless of how many lithium-ion batteries you wire in series, it will resemble a chain. At both ends of the chain, you will have a connection that has no other cell that it can connect to. These are your main + and - connections.&nbsp;<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;serial1_with_watts.jpg&quot;,&quot;filesize&quot;:273978,&quot;height&quot;:830,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/KlLUHq6I1IeZPR2y9Crd7OA7ZTA6eDAUDxa82V63.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/KlLUHq6I1IeZPR2y9Crd7OA7ZTA6eDAUDxa82V63.jpg&quot;,&quot;width&quot;:1040}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/KlLUHq6I1IeZPR2y9Crd7OA7ZTA6eDAUDxa82V63.jpg"><img src="https://admin.cellsaviors.com/storage/KlLUHq6I1IeZPR2y9Crd7OA7ZTA6eDAUDxa82V63.jpg" width="1040" height="830"><figcaption class="attachment__caption">serial1_with_watts.jpg 267.56 KB</figcaption></a></figure>NEVER connect the + and - from the same cell together. Also, never connect the - connection of a set of series-connected cells to the + connection on the other end. Doing either of these things will more than likely lead to an immediate fire.&nbsp;<h3>Can You Charge Lithium Batteries In Series?</h3>So, now you know why it's necessary to put lithium-ion batteries in series and how to do it. The next thing that probably comes to mind is, ‘Can lithium-ion batteries be charged in series?’ Well, there’s good news. You can definitely charge lithium-ion batteries in series. After all, it would be super annoying to have to take your cells out of a series configuration just so they can be charged.&nbsp;Ideally, all the cells will have an equal-to-very-close resistance. Because of that, the voltage applied to the cells in series is evenly divided among all of the cells. So, if you have 10 cells in series and apply 42 volts across the entire group, then each cell will only ‘see’ 4.2 volts.&nbsp;<h3>Conclusion</h3>Several key questions were answered in this article. So, we would like to take the time to go over them quickly. Can lithium-ion batteries be wired in series? Yes. In fact, they have to be wired in series to be useful most of the time.&nbsp;How do you wire multiple lithium-ion batteries? Lithium-ion batteries are wired in series by attaching the - of the first cell to the + of the next cell in a chain.&nbsp;How do you charge lithium batteries wired in series? To charge lithium-ion batteries in series, simply apply the appropriate charge voltage across the main - and + connections using the standard CC/CV method.&nbsp;We hope this article helped you learn more about how to wire lithium-ion batteries in series. Thanks for reading!

Building a e-bike battery is not a simple process and buying one can be expensive, so building one yourself saves you hundreds of dollars.

How To Build A DIY Lithium Ebike Battery 

How To Build A Lithium Ion Ebike Battery DIY Style

If you want to help support us, allowing us to continue building awesome tools, please consider using our links below when buying products for your builds. We make a small percentage of each sale when you use our links, at no additional cost to you!This list will regularly be updated and expanded so check back every time you visit.&nbsp;Anything that we give a recommendation on, we have used ourselves. We will only recommend products that we ourselves use.Here is a list of the products that we have tested and use ourselves:Salvaging Tools:<ul><li><a href="https://amzn.to/32SIEzh">Flush Cut Pliers</a> - Cheaper</li><li><a href="https://amzn.to/3KVmgWW">Flush Cut Pliers</a> - More Expensive but strong!</li></ul>Cell Charger/Testers:<ul><li><a href="https://amzn.to/3uSQAfe">SkyRC MC3000 - Best</a></li><li><a href="https://amzn.to/3vjjmVy">Opus C3400 - Very Good</a></li><li><a href="https://amzn.to/3vtcaWS">Zanflare - Good</a></li><li><a href="https://amzn.to/3K5f0qB">XTAR VC8 Plus - Also good</a></li></ul>Battery Pack Capacity Tester:<ul><li><a href="https://amzn.to/3KWlDwk">150W Load Tester - Good</a></li><li><a href="https://amzn.to/3MipzrP">180W Load Tester - Better</a></li></ul>IR Testers:<ul><li><a href="https://amzn.to/3rD9FQH">YR1035+ - Better</a></li><li><a href="https://amzn.to/3KSO9yR">SM8124A - Good</a></li></ul>Soldering Irons:<ul><li><a href="https://amzn.to/3nb9JVu">Soldering Iron</a> 100W</li><li><a href="https://amzn.to/3p85bQy">Soldering Iron</a> 80W</li><li><a href="https://amzn.to/3bKZB3x">Soldering Iron</a> 60W</li></ul>Misc Supplies:<ul><li><a href="https://amzn.to/3GcWc7x">18650 Cell Holders</a></li><li><a href="https://amzn.to/3JXWilF">BMS</a></li><li><a href="https://amzn.to/3r34Xuy">Nickel Strips</a></li><li><a href="https://amzn.to/3zIXMvs">Charge &amp; Discharge Connectors</a></li><li><a href="https://amzn.to/33kgg9g">PVC Heat Shrink</a></li><li><a href="https://amzn.to/33miyoE">Spot Welder</a></li><li><a href="https://amzn.to/3GeBWCu">Wire Stripper / Cutter</a></li><li><a href="https://amzn.to/3zIYqZU">Heat Gun</a></li><li><a href="https://amzn.to/3zK7v4B">Multimeter</a></li><li><a href="https://amzn.to/3HQIJCN">Kapton Tape</a></li><li><a href="https://amzn.to/3zHmHiZ">Barley Paper</a></li><li><a href="https://amzn.to/3f6yI8j">Insulator Rings</a></li><li><a href="https://amzn.to/3d6AFR4">Gloves</a></li></ul>Suppliers<ul><li><a href="https://store.santansolar.com/?ref=CellSaviors">Santan Solar</a> - They sell new and refurbished/tested solar panels among other solar and powerwall supplies.</li><li><a href="https://solarsupplyhouse.com?ap_id=Cellsaviors">Solar Supply House</a> - They carry a huge selection of solar and storage supplies along with all accessories you may need.&nbsp;</li></ul>

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When used properly, lithium-ion batteries are a safe, high-density power source for electronic devices. When not used properly lithium-ion batteries can be dangerous or even life-threatening.

Lithium Ion Cells and Battery Safety

When used properly, lithium-ion batteries are a safe, high-density power source for electronic devices, vehicles, and more. When not used properly or when poorly designed or improperly implemented, however. lithium-ion batteries can be dangerous or even life-threatening.So, if you plan on building a lithium-ion battery pack, it's important to have a basic understanding of how batteries work and a healthy respect for the dangers associated with lithium-ion batteries.The most important things you can do to practice good lithium-ion battery safety is not make assumptions about what you are working with, check your cell spec sheets, take your time when building your battery, ask questions when you are confused, and use the online battery communities as a resource, build a small battery pack first, don’t let your projects out of your sight and as always, properly dispose of your lithium-ion battery cells.&nbsp;In this article, we will go over the most important aspects regarding lithium-ion battery safety. We will cover the do’s and don’ts, and we will provide guidance on how to keep your battery packs as safe as possible.&nbsp;<h3>If You Are Not Sure - STOP!</h3>There is no room for guessing when dealing with lithium-ion batteries. So, if you are not 100% certain what your cells are capable of, then stop! Guessing can result in a fire, property damage, and loss of life.&nbsp;Remember, lithium-ion batteries are capable of delivering much higher currents than conventional alkaline batteries. This is because lithium-ion batteries have a far lower ISR (Internal Series Resistance) than conventional AA, AAA, C, and D battery cells.&nbsp;<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;18650 vs AA.jpg&quot;,&quot;filesize&quot;:67055,&quot;height&quot;:383,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/hmevFforuLqG1ZW8lTxG7rsMgkfmRoG8BMa7qK5K.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/hmevFforuLqG1ZW8lTxG7rsMgkfmRoG8BMa7qK5K.jpg&quot;,&quot;width&quot;:480}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/hmevFforuLqG1ZW8lTxG7rsMgkfmRoG8BMa7qK5K.jpg"><img src="https://admin.cellsaviors.com/storage/hmevFforuLqG1ZW8lTxG7rsMgkfmRoG8BMa7qK5K.jpg" width="480" height="383"><figcaption class="attachment__caption">18650 vs AA.jpg 65.48 KB</figcaption></a></figure><h3>Check Your Cell Spec Sheets</h3>Each type of lithium-ion cell has its own ratings and limits. These limits should never be exceeded! Some of these limits, such as maximum charge voltage, are obvious and universal for all lithium-ion cells. There are other ratings, however, that vary from cell to cell and you need to know them.Consider this example: You have two types of cells. One of them can handle 10 amps of current and the other can only handle 6. If you are using those cells to power a device that takes 9 amps, one of those cells will perform very well and they could certainly cause a fire and it might even explode! The worst part is that if you are running a cell above its maximum current, it can take quite a bit of time before things start to heat up on the outside. By then, it's often too late. This is why it’s important to always know what your cells are capable of before you use them. &nbsp;<h3>Ask, Learn, And Discuss</h3>The internet is an excellent source of free information. Check Facebook and Discord for battery communities. There are literally hundreds of thousands of people willing to help you right now and for free. There are also plenty of forums and other communities that are not on traditional social media. A quick google search for ‘electronics community’ or ‘battery building forum’ will turn up some useful results. The <a href="https://diysolarforum.com/">DIY Solar Forum</a>,&nbsp; <a href="https://endless-sphere.com/forums">Endless Sphere’s forum</a>, and <a href="https://secondlifestorage.com/index.php">Second Life Storage</a> are three that I can highly recommend.&nbsp;So, get out there and be a part of the community. Don't be afraid to ask questions. Who knows, maybe one day after you learn more about the field, you could help someone else.<h3>Take Your Time</h3>Don't be in a rush! Remember, no one is making you build this battery and it's definitely not a race. So, take your time when approaching these things, they are dangerous!&nbsp;You know the old saying, 'measure twice cut once'. Check, double-check, and triple-check your wiring, fuses, connections, and welds.<h3>Start Small</h3>Don't try to build a massive battery for your very first project. In large batteries, there are many more connections and individual components to deal with. So, it's best for a newcomer to start small and go from there.&nbsp;We recommend building a small battery to get acquainted with the principles and to learn what not to do on a small scale, avoiding a larger more costly incident if there is one. If you are just starting out with learning to build batteries, then we recommend that you check out <a href="https://homeio.info/shop/6-cell-stackable-weld-free-battery-module-for-18650.html">Omnicell kits</a>.&nbsp;Omnicell kits make it easy to put together small battery backs without having to spot weld or own any other kind of special equipment. When using the Omnicell system, the cells are not welded to the conductor.This makes it easy to add or remove cells later for upgrades and troubleshooting purposes.&nbsp;<h3>Test Your Build</h3>We recommend building a 3S2P battery when you are just starting out. 3S because it will result in a battery that has a commonly usable voltage, and 2P so you can get some experience making parallel groups and connecting them in series. Using commonly available 3000ma cells, a 3S2P battery would be able to provide around 66Wh of energy. There are commonly available <a href="https://amzn.to/3K0WCih">battery testers</a> that are used to verify capacity.&nbsp;There are commonly available low-cost battery testing devices that can measure how much energy is stored in a given battery. If your first battery doesn’t have at least 90% of its rated capacity, then something is wrong with either the cells you used or how you put them together. It could even be something as simple as a single poor solder connection.&nbsp;<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;18650 battery tester.jpg&quot;,&quot;filesize&quot;:234004,&quot;height&quot;:876,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/5Ir435qH4uGLTZOjrhzFWiKoiRVmU8wrKjRzHEXy.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/5Ir435qH4uGLTZOjrhzFWiKoiRVmU8wrKjRzHEXy.jpg&quot;,&quot;width&quot;:565}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/5Ir435qH4uGLTZOjrhzFWiKoiRVmU8wrKjRzHEXy.jpg"><img src="https://admin.cellsaviors.com/storage/5Ir435qH4uGLTZOjrhzFWiKoiRVmU8wrKjRzHEXy.jpg" width="565" height="876"><figcaption class="attachment__caption">18650 battery tester.jpg 228.52 KB</figcaption></a></figure><h3>Know What To Worry About</h3>When it comes to working with batteries, there are some things that you have to worry about, but there are other things that you shouldn't. In fact, When it comes to battery safety, the most important factors are the maximum current draw, maximum battery pack temperature, and maximum cell charge voltage.&nbsp;<h3>Test Your Cells And Equipment</h3>Don't just assume everything is working. Components, fixtures, connections, and test equipment will all eventually fail and they will fail at different rates. So, make sure to regularly check your equipment to make sure everything is functioning as it should.&nbsp;You also need to check your cells. Don't get in the habit of trusting a particular source. No matter how good the cells are, always check each and every one of them.<h3>Keep Your Eyes On Your Projects </h3>While you are still becoming familiar with electronics and batteries, it's easy to make simple mistakes. The problem is, that those simple mistakes can cause big, hot fires. So, until you get a handle on things, make sure to not charge or discharge your battery projects unless they are within eyeshot.This may sound inconvenient but it’s very important when you are just starting to learn. After some amount of time, you will be able to leave your projects unattended, but for now, it’s best to keep an eye on them.&nbsp;<h3>Properly Dispose Of Your Cells</h3>You can't just throw away battery cells! They contain hazardous chemicals that should not be dumped into a landfill. Also, if the battery terminals touch against something metal and form a circuit it could cause a fire that you would ultimately be responsible for.This could easily happen as you have no way of knowing where your trash is going to end up and what it will be placed next to. It’s also important to consider that most trash gets mechanically compacted at some point along the journey. If there are charged lithium-ion cells in there when that happens, there is a high chance of a fire.<h3>What Is Thermal Runaway?</h3>Thermal runaway is just as bad as it sounds. When a thermal runaway occurs, the heat from a single failing cell can quickly propagate to the next cell, causing a dangerous cascading chain reaction.When even just a small part of a lithium-ion cell reaches a certain critical temperature, the chemical components of the cell will begin to physically break down. The reactions that occur as the result of these substances breaking down are exothermic. This means it generates heat. &nbsp; One of the worst parts is the decomposition rate increases exponentially as the temperature rises. As temperature increases, decomposition increases, which increases the exothermic reactions, which produce more heat. The result is a positive feedback loop that can lead to a massive fire.&nbsp;<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;lithium ion cell thermal runaway.jpg&quot;,&quot;filesize&quot;:272539,&quot;height&quot;:773,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/rAOfarP9dk11SlDEre3mhnbsIrtiaBs7RaVlnCK0.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/rAOfarP9dk11SlDEre3mhnbsIrtiaBs7RaVlnCK0.jpg&quot;,&quot;width&quot;:1063}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/rAOfarP9dk11SlDEre3mhnbsIrtiaBs7RaVlnCK0.jpg"><img src="https://admin.cellsaviors.com/storage/rAOfarP9dk11SlDEre3mhnbsIrtiaBs7RaVlnCK0.jpg" width="1063" height="773"><figcaption class="attachment__caption">lithium ion cell thermal runaway.jpg 266.15 KB</figcaption></a></figure><h3>Are Lithium-Ion Cells Really That Dangerous?</h3>After all the warnings, lithium-ion batteries can seem kinda scary. It’s important to remember, however, that when designed and used properly, lithium-ion batteries are safe. In fact, heat-related failures of lithium-ion batteries are actually pretty rare considering how many are manufactured each year.<h3>Types Of Lithium-Ion Batteries</h3>While there are many different types of lithium-ion cells, they all filter down to two basic types: cobalt and manganese. Cell phones, digital cameras, and laptops use cobalt-based lithium-ion because it offers the longest runtimes.&nbsp;Power tools and medical devices tend to use manganese because it offers much better thermal stability as it can sustain temperatures of up to 250°C before becoming unstable. Also, manganese has an extremely low internal resistance, so it's able to deliver high current on demand.Manganese batteries are not perfect, though. Manganese batteries offer a lower energy density than cobalt-based cells. Generally speaking, cells with manganese cathodes provide about half the capacity of cobalt-based cells of equal size.&nbsp;For these reasons, lithium-ion battery manufacturers mix the metals in various ratios.<h3>Lithium-Ion Safety Mechanisms</h3>There are several protection devices built into each lithium-ion cell. These built-in protection devices don’t make lithium-ion batteries safe, they only make them safer. One of the devices inhibits high current surges by using a CID circuit interrupt device that breaks the electrical circuit if the cell's pressure reaches 150 psi. This allows the high-pressure gasses to be vented, which prevents an explosion.&nbsp;In addition to the mechanical safeguards built into the cells, the BMS provides electronic safety features that actually make lithium-ion batteries relatively safe. If the voltage of any cell goes over 4.2V, the BMS control logic effectively disconnects the battery pack from the circuit.&nbsp;The BMS will also disconnect the circuit if the load current reaches an unsafe threshold. These two features alone can prevent most failures from turning into catastrophic events.&nbsp;There are many non-branded replacement batteries that are popular with cell phone users and repair shops because of their low prices. The problem with a lot of these batteries is that they are not manufactured with the same safety standard as the mainstream brands.Considering the sheer number of lithium-ion batteries that are produced, sold, and shipped every year, they have caused very little harm.&nbsp;<h3>Conclusion</h3>As long as lithium-ion batteries are used properly and proper care and respect is given to them, lithium-ion batteries are a safe and reliable power source for our modern world.&nbsp;When it comes to lithium-ion battery safety, it's important to verify cell spec sheets and take your time when building your battery. Also, don’t be afraid to ask questions, and take an active part in the battery communities. Make sure to not attempt to build a massive battery on your first try, keep an eye on your projects, and don’t make assumptions about your cells or test equipment.&nbsp;We understand that all the terms and procedures can be a bit overwhelming to keep track of. That’s why we made a suite of tools to help people build safe, high-quality lithium-ion battery packs. <a href="https://tools.cellsaviors.com/pack-builder">Pack Builder</a> helps you build a properly balanced battery pack based on the capacity and IR (internal resistance) of each cell. <a href="https://tools.cellsaviors.com/pack-planner">Pack Planner</a> will help you to figure out what size battery pack you need to build for a given application.&nbsp;We are always adding more tools to make building battery packs better. Check-in regularly or subscribe to our newsletter to stay up to date!We hope this article helped you learn more about lithium-ion battery safety. Thanks for reading!&nbsp;

We are transitioning away from selling packs and cells, and instead putting our focus on what we originally set out to do. Make awesome resources for the building community.

We are going back to where we started - CellSaviors

Hey Everyone,While I was away on vacation we had some issues with the store. Somehow it was allowing people to place orders for items we had set to “out of stock”. We had to go in and cancel 10s of orders, and on top of that, we haven't been able to reliably keep up with the demand. With all of this occurring, plus the time Jeff and I had to put in to try and fix the site, we were reminded of some things.&nbsp;When Jeff and I started Cell Saviors our goal was to use the store to help pay for the costs of the tools we were building. We never intended for our products to become as popular as they did, which is awesome but creates a lot of issues that take us off our path.Our path is building tools and resources that benefit our ever-growing community.&nbsp;The battery, solar and EV industries will continue to grow, making sure people have a place to learn, build and innovate is and will always be our mission.&nbsp;That being said we will be taking down our store. If you have any open orders or questions feel free to email us at <a href="mailto:sales@cellsaviors.com">sales@cellsaviors.com</a>, all open orders will be fulfilled.This change allows Jeff and I to focus more of our time on the tools suite that we built. We have a lot in the pipeline for that, and it should become much more valuable to the community in the near future. In the next month or two, we will be launching the most comprehensive power-wall / solar generation / off-grid system planner out there.&nbsp; In addition to that, we have several other tools in the works and have plans to move all of our planners and building tools into one seamless workflow for users. We will also be adding the ability for users to create accounts where they will be able to save and store all of their projects.We understand this change is disappointing but our mission was to build amazing tools to help grow this community not to become a battery wholesaler.&nbsp; Thank you all for your support -Bryan &amp; Jeff

Cell Saviors Announcement - 3/31/2022

If you want to know how to test 18650 cells, you are in the right place. Testing cells is one of the most important steps in preparing salvaged 18650 cells for reuse.

How to Test and Grade Lithium-Ion 18650 Cells

If you want to know how to test 18650 cells, you are in the right place. Testing cells is one of the most important steps in preparing salvaged 18650 cells for reuse.<h2>A Quick Overview of The Sorting and Grading Process</h2>If you want a quick overview on what the process looks like, these 7 steps are on how to test and grade cells. If you are looking for a more in-depth overview on what each step looks like, visit the bottom of the article.Step 1: Salvaging - The battery pack is removed from its original casing and the cells are removed from the battery pack. Step 2: Visual Inspection - Cells are looked over to make sure they are not physically damaged and show no signs of leaks. Any cells that show signs of damage are discarded. NOTE: Any cells that are discarded throughout this process should be taken to be properly recycled. Please never throw Lithium battery cells in the trash or recycling bin. Step 3: Cleaning - The glue, paper, and tape that was used to hold the battery pack together is removed from the cells. Step 4: Charging - Cells are brought to a full charge while their temperatures are monitored. Any cells that become abnormally warm during charging or do not hold their charge should be discarded. Step 5: Self-Discharge Test - Voltage for each cell is checked after they have been stored for one week to ensure that voltage has not dropped past a certain threshold. If any voltage drop above .1v is detected after one week, the cell should be discarded. Step 6: Capacity Testing - Cells should be capacity tested and labeled to ensure that they can store the correct amount of energy. Any cell that falls below 90% of original manufacturer capacity should be discarded. Some people go lower depends on your needs. Step 7: IR Testing - Cells are tested for IR and sorted based on the cells deviation from the manufacturers specifications. Any cells that fall too far outside of the manufacturer's spec should be discarded.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;ezgif.com-gif-maker (16).jpg&quot;,&quot;filesize&quot;:28599,&quot;height&quot;:591,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/f1eX61650OXRaEYobkpPSajuzFV3d4pffIhMFlfw.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/f1eX61650OXRaEYobkpPSajuzFV3d4pffIhMFlfw.jpg&quot;,&quot;width&quot;:894}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;caption&quot;:&quot;sanyo cells&quot;,&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/f1eX61650OXRaEYobkpPSajuzFV3d4pffIhMFlfw.jpg"><img src="https://admin.cellsaviors.com/storage/f1eX61650OXRaEYobkpPSajuzFV3d4pffIhMFlfw.jpg" width="894" height="591"><figcaption class="attachment__caption attachment__caption--edited">sanyo cells</figcaption></a></figure><h2>Detailed Steps on Salvaging 18650 Cells</h2>The process of salvaging 18650 cells properly can be quite involved. There are several key factors to consider and processes to understand in order to properly salvage, test, and sort 18650 cells.It’s important to make sure that the cells you are salvaging have no leaks, and don’t get hot when they are charging or discharging. Also, it’s important to test each cell for capacity and group them based on those figures.So, here is a detailed explanation of how we salvage, test and grade cells before they are shipped to our customers:<h3>Salvaging</h3>When mass-producing lithium ion battery packs, a significant amount of adhesives and permanent fasteners are used. This can, at times, make the salvaging of cells difficult.That’s why our first step is to remove the battery packs from whatever device or housing they were installed in. After that, we break down the battery packs, and separate the cells.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;ezgif.com-gif-maker (17).jpg&quot;,&quot;filesize&quot;:50162,&quot;height&quot;:320,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/e65JmzB4AfEpjMwoj5Arvd66xOEgod6ig77PwP9d.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/e65JmzB4AfEpjMwoj5Arvd66xOEgod6ig77PwP9d.jpg&quot;,&quot;width&quot;:480}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;caption&quot;:&quot;pack breakdown&quot;,&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/e65JmzB4AfEpjMwoj5Arvd66xOEgod6ig77PwP9d.jpg"><img src="https://admin.cellsaviors.com/storage/e65JmzB4AfEpjMwoj5Arvd66xOEgod6ig77PwP9d.jpg" width="480" height="320"><figcaption class="attachment__caption attachment__caption--edited">pack breakdown</figcaption></a></figure>Where Can I Find 18650 Batteries? All over the place. Our modern world is literally powered by them. You can find 18650 cells in things like discarded scooter batteries, modem battery packs, and old laptop battery packs.How Do You Break Down A Battery Pack? The first step is to remove the battery pack's exterior casing. After that, you may have to pry or otherwise work loose the battery pack from the casing. Then, the nickel strip needs to be carefully removed from the cells.Once that is done, you can generally break loose any adhesives or hot glue that is used to hold the cells together. Once you have the cells freed, the final step is cleaning any remaining debris off of the cells.<h3>Visual Inspection</h3>After that, the next step is to inspect the cell for any visible signs of damage. A small scratch on a cell’s wrapping is not a major cause for concern, but if a cell is swollen, leaking, or discolored, it is discarded. If a cell has leaked, it can have a somewhat sweet smell to it.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;ezgif.com-gif-maker (18).jpg&quot;,&quot;filesize&quot;:53891,&quot;height&quot;:360,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/R14XHM5EWb0MGYoLBxwCf6HOnG25V68vQPb7UZFY.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/R14XHM5EWb0MGYoLBxwCf6HOnG25V68vQPb7UZFY.jpg&quot;,&quot;width&quot;:480}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;caption&quot;:&quot;visual inspection&quot;,&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/R14XHM5EWb0MGYoLBxwCf6HOnG25V68vQPb7UZFY.jpg"><img src="https://admin.cellsaviors.com/storage/R14XHM5EWb0MGYoLBxwCf6HOnG25V68vQPb7UZFY.jpg" width="480" height="360"><figcaption class="attachment__caption attachment__caption--edited">visual inspection</figcaption></a></figure>Why Do Bad 18650 Cells Smell Sweet?Any kind of hole in a cell is a very bad thing. Holes can come from physical impact as well as internal damage. For whatever reason, the electrolytic that is used to separate the negative and positive side of lithium ion batteries. So, if you smell an odd, slightly sweet smell, the cell has a leak it’s electrolyte somewhere and should be properly discarded.Why Is A Swollen Battery Cell So Bad?A lithium ion cell can become swollen by overcharging, over discharging, or other internal damage. A swollen battery cell is dangerous because the swelling is the result of heat and gas that have built up within the cell. If enough heat and gas build up in the cell, it will vent with flame or could even explode.<h3>Cleaning</h3>As mentioned before, lithium ion battery packs are generally put together as a permanent, non-serviceable structure. Before we begin electrically testing any 18650 cells, do your best to remove all the nickel, glue and tape off of each and every cell.If you find that the tape, hot glue, and other adhesives used to hold cells together are too difficult to remove, then try using a heat gun. How well any adhesive works is a function of its temperature. So, applying a little heat is usually enough to loosen the bond. Heat is bad for batteries, so make sure to not heat up the cells for too long. It does not take much surface heat to loosen adhesives and glues. When removing the nickel strip from 18650 cells, it's best to grab the nickel by an edge and slowly roll the nickel strip off of the cells. The rolling action requires the least amount of force to remove the welded nickel, but make sure to not short out the cell when doing this!<h3>Charging</h3>Once we have clean, visually inspected cells, the next step is to charge test the 18650 cells. As they are charging, cells are monitored for heat buildup. If any cells exhibit unusually warm charging characteristics, they are discarded. How Can You Tell If An 18650 Is Getting Too Hot?There are several devices on the market that can precisely monitor 18650 cells during their charging and/or discharging phases. While these devices are useful, that can be somewhat expensive. Another option would be to use an infrared thermometer along with a standard battery charger.You would be surprised, however, by how much insight you can gain about a cell's temperature characteristic with something as simple as the palm of your hand. So, as you are charging your battery cell, keep tabs on their heat output with the palm of your hand. If a battery cell is getting warm under very small charge currents, then the cell more than likely has an internal problem. Why Is It Bad For 18650 Cells To Get Hot?Unless you are putting them under tremendous charge or discharge loads, you should not feel too much heat from your battery cells.If you do, that means the cell either has an extremely high ISR (Internal Series Resistance) or it has some amount of internal discharge. Internal discharge is when the positive and negative electrodes are physically touching inside the cell. <h2>Self Discharge Test</h2>If a lithium ion cell is worn out or damaged, it will have some degree of self-discharge. Self discharge happens because the positive and negative electrodes, to a very small degree, are physically touching inside the cell. As you may expect, this is a bad thing.So, that’s why when we are testing 18650 cells, we let the cells sit for a full week once they are fully charged. If the voltage of any cell drops by more than 0.1v during that time, the cells should be discarded.Why Do Bad Batteries Drop Voltage Over Time? Internal discharge. When a cell is worn out, the electrodes will literally grow towards each other very slowly. While there is a mechanism inside the cell to keep them from touching, it will eventually happen. When it does, it causes the cell to discharge into itself slowly at first, but increasingly so over time.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;ezgif.com-gif-maker (19).jpg&quot;,&quot;filesize&quot;:20351,&quot;height&quot;:320,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/Kmqa6jjq9uHOHeuwdOLfiVJFYOw8ecGihXEXOZWx.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/Kmqa6jjq9uHOHeuwdOLfiVJFYOw8ecGihXEXOZWx.jpg&quot;,&quot;width&quot;:480}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;caption&quot;:&quot;spotwelding&quot;,&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/Kmqa6jjq9uHOHeuwdOLfiVJFYOw8ecGihXEXOZWx.jpg"><img src="https://admin.cellsaviors.com/storage/Kmqa6jjq9uHOHeuwdOLfiVJFYOw8ecGihXEXOZWx.jpg" width="480" height="320"><figcaption class="attachment__caption attachment__caption--edited">spotwelding</figcaption></a></figure><h3>Do Good 18650 Cells Also Experience Voltage Drop?</h3>Yes, but to a very small degree. There are several factors at play that cause a battery's voltage to drop over time. All cells exhibit some form of self discharge, but for healthy cells this phenomenon happens rather slowly. Expect a good cell's voltage to drop somewhere between 0.5% to 2% per month.<h3>Capacity Testing</h3>As you can see, there are a lot of reasons to discard cells. The cells that have made it this far are then put on a capacity tester to determine how much actual capacity the cell has. If any of them read abnormally low, you guessed it, you should discard those cells..Why Is Capacity Testing Important? Capacity testing is important because of how Battery Management Systems work. If you don't match the amount of capacity in each cell group, one will reach a full charge or be depleted sooner than all the others. To keep things safe, the BMS will shut off the battery if any single cell group hits the over-discharge or over-charge threshold.We designed our Packer Tool to make this part of building a lithium ion battery pack much easier. Once you enter all your cell capacities in the tool, it tells you the most optimal way of packing the cells together. This helps ensure the longest running time and life-span for your battery.<h3>ISR Testing</h3>When learning how to test 18650 cells, IR (Internal Series Resistance), is one of its most important characteristics. The lower the resistance, the less voltage drop the cell will experience under load. This leads to less heat build up, which provides for a longer total cell life and, therefore, a longer battery pack life.For these reasons, each remaining cell is tested for ISR and it’s figures are compared to the manufacturer’s spec sheet. If any cell deviates too much from what the manufacturer states, that cell should be discarded.<h3><figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;ezgif.com-gif-maker (20).jpg&quot;,&quot;filesize&quot;:49909,&quot;height&quot;:360,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/S1OVENPhKq179gkzkaV7GOrJwwOX85sr5SJjfmVU.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/S1OVENPhKq179gkzkaV7GOrJwwOX85sr5SJjfmVU.jpg&quot;,&quot;width&quot;:480}" data-trix-content-type="image/jpeg" data-trix-attributes="{&quot;caption&quot;:&quot;v&quot;,&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--jpg"><a href="https://admin.cellsaviors.com/storage/S1OVENPhKq179gkzkaV7GOrJwwOX85sr5SJjfmVU.jpg"><img src="https://admin.cellsaviors.com/storage/S1OVENPhKq179gkzkaV7GOrJwwOX85sr5SJjfmVU.jpg" width="480" height="360"><figcaption class="attachment__caption attachment__caption--edited">v</figcaption></a></figure>Why Is It Important For All The Cells To Have The Same ISR?</h3> The cell’s ISR governs how hot the cell will get and how much of a voltage drop it exhibits under a given load. So, if one of your P groups has a cell with a much higher IR than the other cells, it will experience more voltage drop than the other cells. This causes energy to flow from the good cells into the bad one, which only exacerbates the issue. And remember, as a cell’s temperature increases, so does its resistance. This creates a potentially hazardous positive feedback loop that will make your battery pack fail a whole lot sooner than it otherwise would have. Also, if a P group has a cell with a very high IR, that will cause the BMS to shut the battery pack down far before the other P groups are totally depleted.<h2>Conclusion</h2>When it comes to working with 18650 cells, learning the process of inspecting cells for visual damage, testing cells for voltage drop, and performing a proper charge and discharge test for each and every cell is crucial. Remember, if a lithium ion battery pack is built with unmatched cells that have many different capacities and internal resistances, the end result could be unsatisfactory or even dangerous. We hope this article helped you learn how to test 18650 cells yourself.

Testing and Grading Process

Lithium-ion is currently the best battery chemistry that humanity has. It is one of the best choices when building a battery pack from 18650 cells. Our helpful and informative how-to build guide lays out a clear, concise path for something that can otherwise be overwhelming.

How to Build A Battery Pack From 18650 Cells

Building A Battery Pack From 18650 Cells

When designing a battery powered system from scratch, there are many factors to take into consideration. How do you size a nickel strip for building a battery? How do you know which wire size to use? Find the answers here!