About this replacement
Mobile Warming Fieldsheer — 7.4V Li-ion Replacement Battery (ASA14U01)
This is a 7.4V, 2600mAh Li-ion replacement battery for Mobile Warming Fieldsheer heated clothing. It fits the Fieldsheer jacket, vest, and glove lineup that uses the ASA14U01 pack. Swap it in when your original battery no longer holds a charge or stops powering your heating elements.
- Fieldsheer jacket, vest, and glove compatibility: These garments share the same 7.4V power rail and use the same ASA14U01 connector and BMS handshake, so one replacement battery covers the full range without modification.
- Bench tested on actual hardware: We ran this cell through full charge-discharge cycles on Fieldsheer hardware. The BMS held correct cutoff voltage on both charge termination and low-cell protection, and the pack delivered consistent output across all three heat settings.
- First-use heat setting: Start on the lowest heat setting for the first 10 minutes on a new battery. The heating elements pull significant current at maximum heat, and a brief low-power warm-up lets the cells stabilise before sustaining that full current draw.
Heated jacket not reaching full heat level on a new battery
If the garment runs on medium but struggles to sustain the highest setting, the battery cell voltage is likely sitting below the threshold the controller needs to drive maximum wattage through the elements. A fresh Li-ion cell straight from storage may be partially discharged — typically around 3.7V per cell rather than the 4.2V peak. Charge the pack fully before expecting full heat output. Once both cells reach 4.2V (8.4V combined), the controller can deliver full power to the heating panels.
Heating elements cutting out mid-use on maximum setting
Maximum heat draws three to four times the current of the low setting, and if the battery's BMS detects sustained high current near its protection threshold, it will trip and cut output to protect the cells. This shows up as the garment going cold suddenly, often after 20–30 minutes on high. Switch to medium heat, wait 30 seconds, then switch back to high — this resets the BMS trip without needing to power the pack off completely. If it cuts out repeatedly, check that the battery connector is fully seated, as a loose connection creates resistance that mimics an overcurrent event.