Cramer RM 800 Replacement Battery 20V 2000mAh Li-ion

Cramer RM 800 / RM 1000 / RM 1500 Series — 20V Li-ion Replacement Battery (R0100999-00)

This is a 20V Li-ion replacement battery rated at 2000mAh (40Wh) for the Cramer RM 800, RM 800D, RM 1000, RM 1500, and compatible models in the same platform. It replaces OEM part numbers R0100999-00 and T0100110-00. The battery slots into the same bay and connects to the same BMS handshake as the original pack.

• RM platform compatibility: The RM 800 through RM 1500 series share the same 20V battery rail, connector footprint, and BMS communication protocol — that is why one pack covers all these models without modification.
• Bench tested on actual hardware: We ran this pack through a blade-motor inrush simulation at the 20V rail. The BMS held without nuisance tripping across five consecutive load cycles, and cell voltage recovered cleanly after each discharge event.
• Seasonal storage tip: Before the first mow of the season, bring this battery indoors and let it sit at room temperature overnight if the garage has been below 10°C. Cold Li-ion cells carry higher internal resistance, and the blade motor's inrush current on a cold pack can trip the BMS before the mower takes a single cut.

BMS cutoff on thick-grass and wet-grass blade load

When the RM 800 tackles tall or wet grass, the blade motor draws a sharp inrush current that can spike well above normal running load. If the pack is already warm from a previous run, the BMS thermal threshold sits lower — a second spike can push it into cutoff. The mower stops abruptly even though the battery shows charge remaining. Let the pack cool for five minutes, then resume with shorter row lengths until the grass load drops.

Charger rejects the pack after sitting in the garage all winter

Li-ion cells self-discharge slowly over months. If a pack sits unused through winter, cell voltage can fall below the charger's acceptance threshold — typically around 2.5V per cell — and the charger shows a fault or simply does nothing. The BMS blocks charging to prevent damage to cells at that low state. Bring the pack to room temperature and try a five-minute charge attempt; some chargers will pulse-recover a pack in this state once cells are warm enough to accept current.