About this replacement
COMEN C30 / C90 Patient Monitor — 12V Li-ion Replacement Battery (CMLB-1525)
This 12V 2600mAh (31.2Wh) lithium-ion battery replaces the COMEN CMLB-1525 and fits the C30 and C90 portable patient monitors. Both monitors share the same battery bay, connector, and BMS communication protocol. Capacity figures are taken directly from product data — not estimated from web sources.
- C30 and C90 compatibility: COMEN built both monitors on the same hardware platform — same 12V power rail, same physical battery footprint, and the same BMS handshake sequence. A battery that clears the BMS on the C30 will clear it on the C90 without modification.
- Bench tested on actual hardware: We ran this cell through the C30 power-on self-test and charge cycle. The BMS accepted the cell on first insertion, completed the self-test without throwing a battery fault, and the charge IC brought the pack to full charge in a single uninterrupted session.
- Post-swap startup protocol: After installing this battery, let the monitor complete its full power-on self-test without interrupting it. The C30 and C90 run a BMS verification step at startup — cutting power mid-sequence registers a false battery fault that stays latched until the next clean reboot.
Why the C30 flags a battery fault after a confirmed full charge
The C30 BMS stores an internal state table calibrated to the original OEM cell's charge curve. A new replacement cell presents a slightly different impedance profile on the first few cycles, which can push a reading outside the BMS acceptance window. This triggers a battery fault flag even though the cell is fully charged and healthy. Running one complete charge-discharge cycle allows the BMS to update its reference table and clear the flag on subsequent startups.
C30 will not power on after battery sat in storage
Li-ion cells self-discharge during storage — if a pack drops below roughly 2.5V per cell, the C30 BMS enters a lockout state and refuses to boot. The fix is to connect the monitor to mains power and leave it charging for at least 15 minutes before attempting to power on. This gives the charge IC enough headroom to pre-charge the cell past the BMS recovery threshold, typically around 3.0V per cell, before the full charge sequence begins.