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Home › Batteries › PX21
4.5-volt specialty battery

PX21 is the same as 523

1What it is2Other names3Facts4Buy it
  1. 1

    What it is

    523

    PX21 is just another name for 523. Same battery, different label, so you can buy either one.

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  2. 2

    Names you might see in the store

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

    5233LR501306AP1306A
  3. 3

    Quick facts

    Size
    As long as an AA, but much fatter
    Power
    4.5 volts
    Keeps in a drawer for
    About 5 years
    Rechargeable?
    No, use once
    Found in things like
    Vintage camerasPC motherboards (CMOS)Remote controls
  4. 4

    Where to buy it

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

    Amazon searchEnergizer listings, any pack sizeSearch Amazon for Energizer 523
    See results on Amazon →
    Amazon searchMulti-packs from any brandSearch Amazon for PX21 (523) multi-packs
    See results on Amazon →
    Amazon searchDuracell listings, the same batterySearch Amazon for Duracell 523
    See results on Amazon →

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See it at real size

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

523US quarterAA

What do the letters mean?

Battery names are a code. Here’s how to read PX21:

PX21Legacy generic for this cell
523Physical cell: 16.8 × 49.9 mm, 4.5V alkaline high-v

The same battery from each brand

BrandTheir name for it
Official name3LR50
Shop name523
Energizer523

Exact measurements

Width
16.8 mm (0.661 in)
Length
49.9 mm
Voltage
4.5V (empty at 2.7V)
Energy stored
580 mAh
Weight
—
Made with
Alkaline (stacked cells)
Works between
-10 … 50 °C
Official code
3LR50 · ANSI 1306AP

Questions people ask

Is PX21 the same as 523?

Yes. They’re the same battery with different names. You might also see 523, 3LR50, 1306AP, 1306A.

How long will a spare keep in a drawer?

About 5 years if it stays cool and dry.

Can I recharge it?

No. Never try to recharge it.

523
5234.5-volt specialty battery
Search Amazon for PX21As an Amazon Associate, KnowYourBatteries.com earns from qualifying purchases.

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1What it is2Other names3Facts4Buy it