Aetertek AT-211 mini Compatible Battery 7.4V 500mAh

Aetertek AT-211 Mini / AT-215 / AT-216 / AT-218 — 7.4V Li-Polymer Replacement Battery

This 7.4V 500mAh lithium-polymer cell replaces the rechargeable battery inside Aetertek training collars, including the AT-211 Mini, AT-215, AT-216, and AT-218. It restores power to the collar's stimulus and receiver circuits after the original cell has faded from repeated charge cycles. Voltage and capacity match the OEM spec exactly.

• AT-211 Mini, AT-215, AT-216, AT-218 compatibility: These collars share the same 7.4V two-cell lithium-polymer architecture and physical battery bay dimensions — 48.00 × 22.50 × 12.00mm — so one cell fits across the range without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the AT-211 Mini receiver unit. The BMS held cutoff at the correct low-voltage threshold and accepted a charge from the OEM cradle without fault codes or interrupted charging.
• Stimulus output after reinstall: If the collar powers on but delivers no stimulus or inconsistent output, check that the battery connector is fully seated — a partial connection on this collar's JST-style plug causes intermittent BMS communication errors, not a dead cell.

Why the AT-211 Mini stops responding mid-training session

The AT-211 Mini's receiver draws a short current spike each time a stimulus command fires. As the original cell ages and internal resistance climbs, that spike causes a momentary voltage drop that triggers the BMS undervoltage cutoff — even when the indicator shows charge remaining. The collar goes silent, and the transmitter shows no fault. Swapping to a fresh cell with lower internal resistance eliminates the sag. If the problem returns quickly after a new install, inspect the charging contacts on the collar body for corrosion before assuming a faulty cell.

Collar powers on but shuts off within seconds of first use after battery replacement

This happens when the replacement cell ships at storage voltage — typically around 3.7V per cell, or 7.4V combined — and the collar's BMS interprets that as a low-battery condition on first draw. The fix is straightforward: place the collar on the OEM charging cradle for a full charge cycle before use. Once the cell reaches 8.4V (4.2V per cell) the BMS clears the protection state and normal operation resumes. Do not attempt to bypass the cradle charging with a generic Li-Po charger — the collar's charge circuit regulates current specifically for a 500mAh cell.