About this replacement
Craftsman V20 Cordless Blower Series — 20V Li-ion 4.0Ah Replacement Battery (CMCB204)
This is a 20V Li-ion replacement battery rated at 4000mAh (80Wh), built to the CMCB204 spec. It fits the Craftsman V20 Cordless Compact Blower (CMCBL0100, CMCBL0100B) and the V20 Cordless Brushless Axial Blower, along with 82 additional V20-platform tools. The OEM part numbers covered are CMCB204, CMCB204-2, and CMCB205.
- V20 platform compatibility: All tools in the Craftsman V20 line share a common 20V rail voltage and the same slide-in connector format. The BMS handshake protocol is consistent across the platform, so one pack communicates correctly with both the blower motor controller and the V20 charger without modification.
- Bench tested on actual hardware: We ran this pack through full charge-discharge cycles on a V20 blower and monitored BMS response during motor-start inrush. The overcurrent threshold held correctly on trigger pull, and the charger recognised the pack without error from the first connection.
- V20 blower motor-start conditioning: On first use, run the blower at low speed for two full discharge cycles before sustained high-speed operation. This lets the BMS record the actual inrush current signature of your specific motor before it locks overcurrent protection thresholds permanently into firmware.
BMS cutoff on trigger pull — why the blower shuts off the instant you fire it up
The V20 blower motor draws a spike of current at start that can be two to three times the running draw. If the BMS hasn't profiled this inrush yet — or if the cell voltage is sitting low after storage — it reads the spike as a fault and trips the overcurrent protection. The pack shuts off before the motor even reaches running speed. Charge the pack fully to 20V, let it rest for 10 minutes off the charger, then trigger the blower at low speed first to let the BMS log the inrush before going to full throttle.
Charger blinks red and never starts a charge cycle on a new or stored pack
Craftsman V20 chargers have a minimum acceptance voltage — typically around 10V on a 20V pack. After extended storage, cell voltage can drop below this threshold and the charger refuses to start. The red blink is the charger's way of rejecting the pack, not a sign the pack is dead. Connect the pack to the charger and leave it for 15 to 20 minutes without disconnecting — most V20 chargers will attempt a low-current recovery pulse if the pack stays on the contacts. If the light shifts from red to solid or begins a charge sequence, the BMS has recovered; if it stays red past 20 minutes, measure cell voltage across the pack terminals and confirm you're reading at least 10V before troubleshooting further.