Birchmeier REC 15 AC1 18V Replacement Battery 6000mAh

Birchmeier REC 15 AC1 / REC 15 AC2 / REX 15 AC1 Series — 18V Li-ion Replacement Battery (12070301)

This 18V 6000mAh lithium-ion battery pack replaces OEM part numbers 12070301, 12070401, and 12070501. It fits the Birchmeier REC 15 AC1, REC 15 AC2, REC 15 PC1, REX 15 AC1, and nine additional models in the same cordless sprayer family. Capacity is 108Wh — identical to the original pack.

• REC/REX series compatibility: These models share the same 18V power rail, physical connector, and BMS handshake protocol. The pump motor draw and spray control logic were validated against the same battery interface across the AC1, AC2, and PC1 variants, so one pack covers the full range.
• Bench tested on actual hardware: We cycled this pack through repeated pump-start and sustained spray load sequences. The BMS held the 18V rail steady through motor inrush and managed cell balancing without nuisance trips during extended continuous operation.
• Pump motor inrush protection: On first use, run the sprayer at low pressure for two full tank cycles before switching to maximum pump speed. This allows the BMS to profile the motor's inrush current signature and set overcurrent thresholds accurately before you push peak draw.

BMS cutoff on sprayer pump start surge

The REC 15 pump motor pulls a sharp inrush current spike the moment the trigger opens. On a new or recently stored pack, the BMS may read that spike as an overcurrent fault and cut the output immediately. This is a protection threshold issue, not a dead cell. Running two low-pressure cycles first lets the BMS log the actual inrush profile and widen its trip window accordingly. After conditioning, sustained pump operation at full pressure should clear without interruption.

Charger not recognising pack after storage

If the Birchmeier charger shows a fault light or refuses to initiate charging on a pack that has been stored, the cells have likely discharged below the charger's acceptance voltage — typically under 2.5V per cell. Most Li-ion chargers won't begin a standard charge cycle below this threshold. Place the pack in the charger and leave it for 15–20 minutes without removing it; many chargers run a slow recovery pulse below 12V total rail before switching to normal charge mode. If the charger accepts the pack after that window, let it complete a full charge to 21.6V before first use.