CellChart
Comparison

CR1220 vs ML1220

The CR1220 and ML1220 share a 12.5 by 2 mm case and a 3 volt rating, so voltage is not what separates them. The CR1220 is a primary lithium cell holding 35 to 40 mAh. The ML1220 is rechargeable, holds about 16 mAh, and sits in positions where the device keeps charging it.

CR1220 and ML1220 drawn side by side at the same scale: CR1220 is 12.5 mm across, 2 mm thick; ML1220 is 12.5 mm across, 2 mm thickCR1220ML1220 CR1220 3V + ⌀ 12.5 mm 2 mm ML1220 3V + ⌀ 12.5 mm 2 mm
CR1220 vs ML1220 at the same scale: both 12.5 mm across, 2 mm thick.
CR1220ML1220
ChemistryLithium manganese dioxide (Li/MnO2)Lithium manganese rechargeable (3 V)
Voltage3 V3 V
Diameter12.5 mm12.5 mm
Height2 mm2 mm
Capacity35-40 mAh16-17 mAh (rechargeable)
Also sold asDL1220, ECR1220, BR1220 (wide-temp variant), 5012LC–

Unlike the LIR pairs on this site, this is not a voltage story. Both cells are 3 volts and the same size. The difference is what the device does to them. ThinkPads and many other laptops, cameras and handheld consoles use the ML1220 as a real-time-clock backup that the board recharges whenever main power is present. A primary CR1220 put there receives charge current it cannot accept, and it can leak or vent onto the motherboard.

The ML1220 in those machines rarely looks like a bare coin. It usually comes wrapped in yellow film with a two-pin connector on a short lead, and replacements are sold pre-wired for common connectors. That packaging is a hint that you are looking at the rechargeable type, but the code on the cell or in the service parts listing is what settles it. If you solder one in yourself, use a tabbed ML1220, never put direct heat on the cell, and never fit a CR1220 because it happens to be the one in the drawer.

The opposite swap is safe and simply short-lived. An ML1220 fitted where a CR1220 belongs, in an older Toyota or Subaru fob, a kitchen scale, a watch or a medical monitor, runs at the right voltage but holds less than half the charge, and nothing in those devices recharges it. It works for a while and then dies early. Some boards do hold a primary CR1220 as CMOS backup in a plain holder that never charges it, which is why the label on the slot tells you little and the code on the old cell tells you everything.

All about CR1220 All about ML1220

Frequently asked questions

Can I use a CR1220 instead of an ML1220 in a laptop?
No. The laptop recharges its clock cell whenever it has power, and charge current into a primary CR1220 can make it vent or leak onto the board. Fit a rechargeable ML1220 that matches the connector or tabs your machine uses, even though a CR1220 is exactly the same size.
Can an ML1220 replace a CR1220?
It is safe, since both are 3 volt cells, but it holds about 16 mAh against 35 to 40, less than half, and a fob or scale will not recharge it. Expect it to die early. Use it to bridge a gap at most, then fit the CR1220 the device was designed for.
How do I know whether my laptop uses an ML1220?
Read the code on the old cell. A yellow-wrapped cell on a two-pin lead is typical of the ML1220 used as clock backup in ThinkPads and many other laptops. If the wrap hides the marking, check the service manual or the replacement part listing for your exact model before ordering.
How long does an ML1220 last?
Typically 5 to 10 years. The device keeps it topped up with very shallow cycles, so calendar age rather than cycle wear usually ends it. Clock drift comes first, then full resets of the time and firmware settings whenever the machine loses main power.

⚠️ 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.