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Home › Batteries › 21700
Rechargeable flashlight battery

21700 battery

1What it is2Safety3Other names4Facts5Buy it
  1. 1

    What it is

    21700

    21700 is a rechargeable flashlight battery, much bigger than an AA. It gives 3.6 volts.

    Get 21700 on AmazonAs an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

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  2. 2

    Safety first

    This one is rechargeable

    It gives more power than a normal battery. Only use it in things made for it.

  3. 3

    Names you might see in the store

    All of these are the same battery. Any of them will work.

    INR21700
  4. 4

    Quick facts

    Size
    Much bigger than an AA
    Power
    3.6 volts
    Keeps in a drawer for
    About 3 years
    Rechargeable?
    Yes
    Found in things like
    High-output flashlightsPower tools
  5. 5

    Where to buy it

    As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

    Our pickThe exact match, 4-packEnergizer 21700 3.6V Battery (4-Pack)
    Check Price on Amazon →
    Best value10-pack, handy to keep in a drawer21700 3.6V Battery Value Pack (10-Pack)
    Check Price on Amazon →
    Other brandDuracell, the same batteryDuracell 21700 / 21700 3.6V Battery
    Check Price on Amazon →

    Buttons open amazon.com 🇺🇸, picked from your country.

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See it at real size

21700 next to a US quarter and an AA battery. “Real size” matches your hand once your screen is set up in Measure it.

21700US quarterAA

What do the letters mean?

Battery names are a code. Here’s how to read 21700:

2121 mm diameter
70070.0 mm length
Li-ion3.6V rechargeable

The same battery from each brand

BrandTheir name for it
Official name21700

Exact measurements

Width
21.0 mm (0.827 in)
Length
70.0 mm
Voltage
3.6V (empty at 2.5V)
Energy stored
4500 mAh
Weight
68 g
Made with
Lithium-ion rechargeable
Works between
-20 … 60 °C
Official code
21700

Questions people ask

Is 21700 the same as INR21700?

Yes. They’re the same battery with different names. You might also see INR21700.

How long will a spare keep in a drawer?

About 3 years if it stays cool and dry.

Can I recharge it?

Yes, it’s rechargeable. Only charge it in a charger or device made for it.

21700
21700Rechargeable flashlight battery
Get 21700 on AmazonAs an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

Something wrong or missing? Tell us

1What it is2Safety3Other names4Facts5Buy it