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:Misc 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>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/3nb9JVu">Soldering Iron</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!

How To Size Wire, Fuses, And Nickel Strip For A Lithium Battery Pack - CellSaviors

How To Size Wire, Fuses, And Nickel Strip For A Lithium Battery Pack

In this article, we will cover what lithium ion cells are and where to find them. We will also go over how to remove, test, sort, and charge salvaged 18650 cells. Let's get started!

How To Salvage 18650 Cells and Batteries - CellSaviors

How To Salvage 18650 Cells

In a perfect world, a lithium ion battery pack would last forever. In the real world, however, battery packs are known to degrade over time. Keep reading to learn how to get more cycles out of your lithium ion cells.

How To Get More Cycles Out Of 18650 Lithium Ion Cells

In a perfect world, a lithium ion battery pack would last forever. In the real world, however, battery packs are known to degrade over time. At some point, a battery pack will degrade so much that it should no longer be used. The number of times a battery pack can be cycled before it needs to be discarded or repaired is known as its cycle life. Depending on the type of cells you have and how you treat them, lithium ion cells can have a cycle life ranging anywhere from 500 to 2000 or more cycles. The most effective things you can do to get more cycles out of your 18650 cells are to lower the charge voltage and raise the cutoff voltage. You can also minimize stresses on your cells by using as many cells in parallel as possible. When a battery pack has more parallel cells, it will produce less heat when charging or discharging. In this article, we will discuss tips and procedures that will ensure that you get the most cycles out of your lithium ion battery packs.<h2>So, What Exactly Causes Lithium-ion Cells To Age?</h2>Lithium-ion battery cells work based on the movement of ions between the positive and negative electrodes. In an ideal battery, this mechanism would work perfectly forever. Unfortunately, however, the lithium ion charging and discharging process causes a tiny amount of damage each time. This manifests itself as the battery losing its ability to hold as much of a charge as it did when it was new. A battery's State of Health is a function of its capacity, internal resistance, level of self-discharge, and other factors. When it comes to 18650 battery cells, there are several important parameters to keep up with. These parameters are especially important if you are working with salvaged cells. So, if you would like to learn more about these key aspects, then check out our article on <a href="https://tools.cellsaviors.com/blog/how-to-salvage-18650-cells">how to properly salvage 18650 cells</a>.<h3>Capacity</h3>Capacity is rated in mAh (milliamp Hours). A milliampere/hour is how long a battery can sustain a constant discharge of electric energy at a certain rate. A cell's actual mAh value is a function of its discharge current, temperature, and wear level. In fact, how a cell is charged can even affect its capacity.<h3>CDR (Continuous Discharge Rating)</h3>CDR is a measure of how much current a cell can deliver continuously. This figure will always be lower than a cell’s peak discharge rating. For example, if a cell can deliver 5 amps continuously, it may have a peak discharge current of 20 amps or more. The manufacturers spec sheet will state how long the cell can sustain the temporarily higher current draw.<h3>Charge Current</h3>Charge current is the amount of amps that a given cell can be charged at. Most of the time, there are two values listed for charge current. These values are typical, minimum, and maximum. If you are wanting to extend the life of your cells, choose a charge current that leans more toward the cell’s typical or minimum values.<h2>So, What Exactly Is A Lithium Ion Cell Cycle?</h2>Believe it or not, there is really no clearly defined understanding of what a complete cycle is. Generally, when a 18650 battery is fully charged, fully discharged, and then fully charged again, that is considered to be one cycle. The confusion comes from the fact that the charge voltage and cutoff voltages can be chosen by the user. So really, you choose what a cycle really is. 18650 lithium-ion battery cells have a maximum charge voltage of 4.2 volts. The low voltage cutoff, which is when a cell is considered to be totally depleted of usable energy, is somewhere between 2.5V and 2.8V. Lithium ion cells also have a max discharge rating. The rating is usually only achievable for 10 to 30 seconds. If you ever go past this mark, it will accelerate the degradation of the cell. This is not an exact figure for all lithium ion cells and depends on the cells you are using. So always make sure to refer to your cell's datasheet when possible.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;batteries.jpeg&quot;,&quot;filesize&quot;:67055,&quot;height&quot;:383,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/s3iqrmQPor4pWbfaqI6sgRkTo7OZrYRdJBWDMbVO.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/s3iqrmQPor4pWbfaqI6sgRkTo7OZrYRdJBWDMbVO.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--jpeg"><a href="https://admin.cellsaviors.com/storage/s3iqrmQPor4pWbfaqI6sgRkTo7OZrYRdJBWDMbVO.jpg"><img src="https://admin.cellsaviors.com/storage/s3iqrmQPor4pWbfaqI6sgRkTo7OZrYRdJBWDMbVO.jpg" width="480" height="383"><figcaption class="attachment__caption">batteries.jpeg 65.48 KB</figcaption></a></figure><h2>What Is Discharging?</h2>As the name implies, discharging is the opposite of charging. So, if charging is when power is going into the battery, then discharging is when power is coming out of the battery.<h2>How Is Cycle Life Calculated?</h2>The SoH or (State of Health) is a percentage that represents your batteries overall health. While SoH is not based on capacity alone, you can get a pretty decent estimation of SoH by calculating the ratio of a cell's measured capacity compared to the ratings provided in the manufacturer's spec sheet. For example, if your cell is supposed to be able to store 2200mAh, but now it is only able to store 2000mAh in it, that cell has a 91% SoH. Generally speaking, an 18650 battery cell is no longer good if it has a SoH of 80% or less. Also, as a lithium ion cell ages, its ISR (Internal Series Resistance) increases. Brand new cells have an ISR of around 20 to 50 mOhms. As a cell is cycled more and more, its internal resistance will increase up to and beyond 400 mOhms. Once a cell gets to this level, it should no longer be used.<h2>How Many Cycles Do 18650 Cells Have?</h2>The average 18650 cell will have a cycle life of 300 - 500 cycles when used at its rated limits. It is important to note, however, that when a cell is exposed to high temperatures and high-drain situations, this can lower cycle life to around 200 cycles. If you go over the maximum discharge current limit, it's even worse. This will decrease the cycle life down to as little as 40 or 50 cycles. In ideal conditions, 18650 cells can achieve much more than 500 cycles. In fact, if you do things right, you can get several thousand cycles out of your cells.<h2>It's Important To Optimize Temperature</h2>Cell temperatures are often overlooked. Always check your spec sheet, but a typical 18650 cell is rated to run between 20 and 25 degrees C. So, when running a battery outside of those ranges, you will see an efficiency loss. In fact, for every 10-degree deviation, you will lose a significant amount of capacity. While not as dangerous, when it comes to the cycle life, running 18650 cells too cold can be just as bad as running them too hot. And while standard lithium ion chemistry is not as sensitive to low temperature conditions as lithium iron variants, make sure to never charge 18650 cells when ambient temperatures are below freezing<h3>Lower Your Charge Voltage</h3>You do not have to charge cells to 4.2 volts per cell. In fact, as you can see in the chart below, if you want the most cycles from your cells, then you should charge them at no more than 4 volts per cell. Charging to 4 volts per cell gives you a little less capacity, but a lot more cycles.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/png&quot;,&quot;filename&quot;:&quot;Screen Shot 2022-03-28 at 5.51.30 PM.png&quot;,&quot;filesize&quot;:124645,&quot;height&quot;:836,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/mkShzg7itdvjslRuguDYEcFc3TZMrjdUZUbK9Dnu.png&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/mkShzg7itdvjslRuguDYEcFc3TZMrjdUZUbK9Dnu.png&quot;,&quot;width&quot;:1858}" data-trix-content-type="image/png" data-trix-attributes="{&quot;presentation&quot;:&quot;gallery&quot;}" class="attachment attachment--preview attachment--png"><a href="https://admin.cellsaviors.com/storage/mkShzg7itdvjslRuguDYEcFc3TZMrjdUZUbK9Dnu.png"><img src="https://admin.cellsaviors.com/storage/mkShzg7itdvjslRuguDYEcFc3TZMrjdUZUbK9Dnu.png" width="1858" height="836"><figcaption class="attachment__caption">Screen Shot 2022-03-28 at 5.51.30 PM.png 121.72 KB</figcaption></a></figure>NOTE: The chart above is for *reference* only and was sourced <a href="https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries">here</a>. You should *never* charge a lithium ion cell over 4.2 volts.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image/jpeg&quot;,&quot;filename&quot;:&quot;JohnRPhoto-44 (1).jpg&quot;,&quot;filesize&quot;:636111,&quot;height&quot;:3893,&quot;href&quot;:&quot;https://admin.cellsaviors.com/storage/vKvc84dB5ufOdTknIAXYMNQBeoERELAe2HD3RUls.jpg&quot;,&quot;url&quot;:&quot;https://admin.cellsaviors.com/storage/vKvc84dB5ufOdTknIAXYMNQBeoERELAe2HD3RUls.jpg&quot;,&quot;width&quot;:5653}" 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/vKvc84dB5ufOdTknIAXYMNQBeoERELAe2HD3RUls.jpg"><img src="https://admin.cellsaviors.com/storage/vKvc84dB5ufOdTknIAXYMNQBeoERELAe2HD3RUls.jpg" width="5653" height="3893"><figcaption class="attachment__caption">JohnRPhoto-44 (1).jpg 621.2 KB</figcaption></a></figure><h2>Raise Your Cut-off Voltage</h2>To achieve the longest run time, lithium ion battery packs generally have a default cut off voltage of 2.5 to 3.0 volts per cell. If you want the most cycles out of your battery, you should increase the cut off voltage to something higher than the LVC (Low Voltage Cutoff) stated in the spec sheet. This partial cycle setup will greatly reduce the stresses on your battery pack, and will, therefore, provide a much longer cycle life. If the battery pack is optimally designed and the best charge and discharge methods are used, it's not uncommon for an 18650 cell to reach 1000 or even 2000 cycles.<h2>Lower Your Charge Current</h2>Not all chargers let you change the charge current. So, if possible, get a charger that has that feature. If you don’t want to have to adjust the settings, then you could always buy an undersized charger. For example, if your battery pack calls for a 4 amp charger, you could always get a 3 amp charger. The slower charger will be compatible with your battery, and it will stress your cells less. The ability to lower charge current is crucial for extending the cycle life of your 18650 battery pack. If you cannot lower the charge current, you can effectively lower the amount of charge current each cell receives by increasing the number of parallel cells in your battery pack. While a fast charge of 1 amp per cell in parallel or more will charge a battery pack quickly, it will reduce the battery packs overall life.<h2>Lower Your Discharge Current</h2>If you want to make your battery pack last as long as possible, it's important to take into consideration your load when designing your battery pack. If possible, design your system so that an individual cell is exposed to no more than 0.5c of discharge current. This can be achieved by building your battery pack with as many cells in parallel as possible. The amount of current each cell has to provide can be calculated like this: Single Cell Amps = (Load Watts / Battery Volts)/Parallel Cells For example, if you have a 7S4P battery that is a 500 watt load, that comes out to about 19.3 amps. Each cell will have to provide 4.8 amps of current. If you doubled your parallel cells by building a 7S8P battery, then each cell would only experience 2.4 amps of current while running the same 20 amp load. NOTE: As battery voltage drops, it will require more current from the battery pack to sustain the same load current. So, when planning your build, it's always a good idea to plan around how many amps your battery will have to provide at the lowest voltage it can run at.<h2>Do 18650 Cells Have A Memory?</h2>No. Lithium-ion batteries don't have a memory effect. So, that means that the first charge does not have to be an 8 to 10 hour charge. Also, because lithium cells have no memory effect, they can be charged and discharged at any time without affecting their capacity. This is in contrast to older battery technologies such as nickel cadmium, which needed to be fully charged and fully discharged to get the most capacity out of them.<h2>What Is The Shelf Life Of 18650 Batteries?</h2>18650 cells have a very long service life when properly stored. They can last up to 10 years on the shelf if kept at typical room temperatures and at their nominal voltage per manufacturer's spec sheet. This will typically be 3.7 volts.<figure data-trix-attachment="{&quot;contentType&quot;:&quot;image&quot;,&quot;height&quot;:480,&quot;url&quot;:&quot;https://cdn.shopify.com/s/files/1/0554/0177/5244/files/JohnRPhoto-52_480x480.jpg?v=1641850511&quot;,&quot;width&quot;:320}" data-trix-content-type="image" data-trix-attributes="{&quot;caption&quot;:&quot;cells&quot;}" class="attachment attachment--preview"><img src="https://cdn.shopify.com/s/files/1/0554/0177/5244/files/JohnRPhoto-52_480x480.jpg?v=1641850511" width="320" height="480"><figcaption class="attachment__caption attachment__caption--edited">cells</figcaption></figure><h2>Conclusion</h2>Battery packs don’t last forever. Due to the unfortunate lack of perfection in the underlying processes that make lithium ion batteries work, they wear out over time. There are, however, some things you can do to get more cycle life out of 18650 cells. Lowering the charge voltage and raising the cutoff voltage are the most effective ways that you can get the most out of your cells. If you want to take things a bit further, you can lower the charge and discharge current by using as many cells in parallel as possible, which will make your battery pack run cooler. We hope this article helped you learn how to get the most cycle life out of your 18650 cells, thanks for reading!