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Rechargeable coin

ML1220 battery: equivalents & specs

The ML1220 is a small 3 volt rechargeable lithium coin cell, 12.5 mm across and 2 mm thick, holding about 16 mAh. Laptops, cameras and consoles use it as a real-time-clock backup battery that the device recharges whenever main power is present.

ML1220 battery drawing: 12.5 mm across, 2 mm thick ML1220 3V + ⌀ 12.5 mm 2 mm
ML1220, face and side profile, drawn to scale: 12.5 mm across, 2 mm thick.
Voltage
3 V
Size (D×H)
12.5 × 2 mm
Chemistry
Lithium manganese rechargeable (3 V)
Capacity
16-17 mAh (rechargeable)

Compatible replacements

  • CR1220: Primary cell of the same size; fitting it in a charging circuit is hazardous.

⚠️ RTC backup circuits charge this cell. Installing a primary CR1220 in its place risks leakage or rupture on the motherboard.

Buying and replacement notes

This is the classic ThinkPad and laptop RTC cell, usually wrapped in yellow film with a two-pin connector pigtail. When an old laptop loses its clock and BIOS settings between sessions, this cell has usually died of old age. Replacements come pre-wired for common connectors; if you solder your own, use a tabbed ML1220, never direct heat on the cell, and never substitute a primary CR1220 since the board trickle-charges this position.

Commonly used in

laptop CMOS/RTC backup (ThinkPads and others)cameras (clock backup)handheld consoles

Need a replacement?

Shop ML1220 batteries on Amazon →

Comparisons

CR1220 vs ML1220

⚠️ Keep away from children. Swallowed button batteries, especially 20 mm lithium coins, cause severe injury within hours. If a child swallows one, call the 24/7 National Battery Ingestion Hotline (US) at 800-498-8666 or poison control at 800-222-1222 immediately. What every parent should know.

Frequently asked questions

My laptop forgets the time when unplugged. Is this the battery?
Very likely. The ML1220 RTC cell holds the clock and firmware settings when all other power is removed. After 5 to 10 years it stops holding charge. A replacement, pre-wired with the right connector for your model, is a cheap and standard repair.
Can I use a CR1220 instead of an ML1220 in a laptop?
No. The motherboard recharges the RTC cell, and charge current into a primary CR1220 can make it vent or leak onto the board. Only fit the rechargeable ML type, matching the connector or tabs your machine uses.
How long does an ML1220 last?
Typically 5 to 10 years in service. It cycles very shallowly, staying topped up whenever the device has power, so calendar aging rather than cycle wear usually ends its life. Symptoms build gradually: clock drift first, then full resets.

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