Battery Building ToolsCell Database M42A

✱ Render

62 g

20700NMC Mooch-tested · 20 A

Molicel M42A

Name: Molicel M42A Lithium Battery Cell
Brand: Molicel

Molicel · released 2019

Capacity4000 mAh14.4 Wh · 232.26 Wh/kg

Mooch continuous20 ASize to this figure

Resistance15 mΩDC internal resistance

Voltage window3.6 V2.5 – 4.2 V

Standard charge2100 mA~1.9 h to full

Build a pack with this cell →Download spec sheet (PDF)Mooch's test ↗

At 4000 mAh, this ranks #3 of 12 20700 cells in our database. Mid-range for capacity among 20700 cells. More capacity than 83% of 20700 cells in our database, but lower discharge than average.

Photos from the community

See the wrap, markings, and terminals up close.

Have this cell in hand?

Community photo submissions are opening soon.

Full specifications

Electrical
Chemistry	NMC
Nominal voltage	3.6 V
Max charge voltage	4.2 V
Discharge cutoff	2.5 V
Max continuous discharge	20A (Mooch-tested)
Mooch CDR (trusted)	20 A
Standard charge current	2100 mA
Standard discharge current	2100mA
Internal resistance	15 mΩ
Physical
Form factor	20700
Weight	62 g
Top type	Flat Top
Protected	No
Performance
Capacity	4000 mAh
Energy	14.4 Wh
Specific energy	232.26 Wh/kg
Power density (gravimetric)	1,161 W/kg
Year released	2019
Operating Limits
Charge temp	0°C to 60°C
Discharge temp	-50°C to 60°C

Independent test data: Mooch's test of the M42A ↗

At the standard 2100 mA charge rate, a full charge takes about 1.9 hours. The last bit is a slow taper to top it off.

Voltage operating window

Cutoff
2.5VNominal
3.6VMax charge
4.2V

Usable range: 1.7V

C-rate conversion: Molicel M42A (4000mAh)

C-Rate	Current (A)	Theoretical runtime
0.2C	0.8 A	5h 00m
0.5C	2 A	2h 00m
1C	4 A	1h 00m
2C	8 A	30m
3C	12 A	20m
5C	20 A	12m

Highlighted row is closest to the rated 20A continuous discharge.

Charging

Rate	Current	Estimated time
0.5C	2,000 mA	~2h 00m
Standard	2,100 mA	~1h 54m
1C	4,000 mA	~1h 00m

These are estimates for the constant-current phase. Real charge time is a bit longer because of the slow taper at the end.

Pack scaling

Series voltage configurations

Config	Nominal V	Max V	Min V	Common use
1S	3.6V	4.2V	2.5V	Flashlights, single-cell devices
2S	7.2V	8.4V	5V	RC vehicles, 7.2V packs
3S	10.8V	12.6V	7.5V	Power tools (10.8V nominal)
4S	14.4V	16.8V	10V	Ebike (small), some power tools
7S	25.2V	29.4V	17.5V	Ebike (24V system)
10S	36V	42V	25V	Ebike (36V system)
13S	46.8V	54.6V	32.5V	Ebike (48V standard)
14S	50.4V	58.8V	35V	Ebike (52V high-power)
16S	57.6V	67.2V	40V	DIY powerwall

Parallel capacity scaling

Config	Capacity	Energy	Max discharge
1P	4,000 mAh	14.4 Wh	20 A
2P	8,000 mAh	28.8 Wh	40 A
3P	12,000 mAh	43.2 Wh	60 A
4P	16,000 mAh	57.6 Wh	80 A
5P	20,000 mAh	72 Wh	100 A
6P	24,000 mAh	86.4 Wh	120 A

Example pack configurations

7S2P

24V ebike / small pack

14 cells25.2V nominal8,000mAh202Wh40A maxCell weight: 0.87 kg (add ~15% for wiring and BMS)

13S4P

48V ebike standard

52 cells46.8V nominal16,000mAh749Wh80A maxCell weight: 3.22 kg (add ~15% for wiring and BMS)

16S4P

DIY powerwall

64 cells57.6V nominal16,000mAh922Wh80A maxCell weight: 3.97 kg (add ~15% for wiring and BMS)

4S6P

Power tool replacement

24 cells14.4V nominal24,000mAh346Wh120A maxCell weight: 1.49 kg (add ~15% for wiring and BMS)

Design a custom pack with this cell:

Pack Planner →Pack Designer →

Application suitability

PowerwallsHigh capacity means more stored energy per cell. Fewer cells needed for a given kWh target.

Ebike PacksGood balance of capacity for range and discharge for hills. Works well in most ebike packs.

Car AudioEnough discharge to handle amplifier bursts without voltage sag.

High-Drain VapingUsable in regulated mods at moderate wattage. Not recommended for mechanical mods.

FlashlightsHigh capacity means long runtime. Great for everyday carry and extended use.

Power ToolsSufficient discharge and capacity for most power tool packs.

Similar cells

Same format and chemistry, within ±500mAh capacity:

Cell	mAh	CDR	Wh	Weight	Wh/kg
Molicel M42A (this cell)	4000	20A	14.4	62g	232.26
AWT AWT 40A 4200mAh	4200	40A	15.1	50g	302

Build with this cell

Pack PlannerSize your pack. Voltage, capacity, runtime, BMS.Pack Designer2D & 3D layout for your exact cell arrangement Pack BuilderBalance cells by capacity and internal resistance

Frequently asked questions

What is the capacity of the Molicel M42A?

What is the maximum discharge rate of the Molicel M42A?

How many M42A cells do I need for a 48V ebike battery?

What does the Molicel M42A weigh?

Can I use the M42A for vaping?

What temperature range can the M42A operate in?

Handling and safety

Lithium cells can be dangerous if mishandled. A few things to keep in mind:

Never charge above 4.2V or discharge below 2.5V.
Store cells at around 3.6-3.8V (roughly 40-60% charge) for long-term storage.
Don't mix cells with different capacities, chemistries, or states of charge in a pack.
Inspect wraps before use. A torn wrap can cause a short circuit.
Always use a BMS or balance charger appropriate for your pack configuration.
Keep cells away from metal objects, keys, and coins. A short across the terminals can cause fire.

Get new tools and build tips

We are always adding tools, cell data, and guides. Drop your email for new tool releases and battery-building tips. No spam, unsubscribe anytime.

Specs come from manufacturer datasheets and independent testing; Mooch-tested discharge ratings are shown when available because they reflect real continuous performance better than headline datasheet numbers. Browse the full 18650 & 21700 cell database to compare every cell.

Disclaimer: We do our best to keep the information on this page accurate, but we cannot guarantee that all specifications are correct or up to date. Cell characteristics can vary between production batches and may change over time. Do not rely solely on this data for safety-critical applications. Always verify against the manufacturer's official datasheet before use.