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Rechargeable coin

ML2020 battery: equivalents & specs

The ML2020 is a 3 volt rechargeable lithium coin cell, 20 mm across and 2 mm thick, rated around 45 mAh. It appears in self-charging key fobs and trickle-charged backup circuits, and it is often cross-shopped with the similar VL2020 used by BMW.

ML2020 battery drawing: 20 mm across, 2 mm thick ML2020 3V + ⌀ 20 mm 2 mm
ML2020, face and side profile, drawn to scale: 20 mm across, 2 mm thick.
Voltage
3 V
Size (D×H)
20 × 2 mm
Chemistry
Lithium manganese rechargeable (3 V)
Capacity
45 mAh (rechargeable)

Compatible replacements

  • VL2020: Vanadium-lithium rechargeable of the same size, the type BMW fobs use; not identical chemistry, match what the device specifies.

Buying and replacement notes

ML (manganese-lithium) and VL (vanadium-lithium) cells overlap heavily in size and role but differ in charge characteristics. Fobs that charge while docked in the ignition, common in 2000s BMWs and some other European cars, mostly specify the VL2020, frequently with solder tabs at a particular angle. If your fob's cell says ML2020, buy ML2020; if VL2020, buy that, tabs and all.

Commonly used in

self-charging key fobssolar devicesbackup power circuits

Need a replacement?

Shop ML2020 batteries on Amazon →

⚠️ 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

Are the ML2020 and VL2020 interchangeable?
They share size and nominal voltage, and hobbyists do swap them, but their charge curves differ and device makers specify one type. For a fob you depend on, match the original marking exactly, including solder tab orientation if the cell is tabbed.
Why does my old fob die overnight?
Rechargeable fob cells wear out after years of cycling, losing the capacity to hold a day's charge. A fresh ML2020 or VL2020 (whichever the fob uses) fixes it. Many replacements require soldering; kits with pre-tabbed cells make the job manageable.
Can I use a CR2025 instead of an ML2020?
Only in a device that never charges its battery, and even then the 0.5 mm height difference may cause fit issues. In a self-charging fob a primary CR cell is a safety risk under charge current. Identify how the device treats its battery first.

More Rechargeable coin cells

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