About this replacement
Trimble Recon 200 / 400 Series — 2.4V Ni-MH Replacement Battery (ACCAA-109)
This is a 2.4V Ni-MH battery rated at 3800mAh (9.12Wh), built to the ACCAA-109 specification. It fits the Trimble Recon 200, Recon 200X, Recon 400, and Recon 400X handheld data collectors. These units are used in GPS surveying, construction staking, and field data logging — environments where battery failure mid-session costs real time on-site.
- Recon 200, 200X, 400, 400X compatibility: All four models share the same 2.4V battery bay, connector pinout, and BMS handshake protocol. Swapping between variants requires no adapters or firmware changes — the pack is electrically identical across the platform.
- Bench tested on actual hardware: We ran the pack through charge and discharge cycles on a Recon 400 unit, monitoring cell voltage balance and BMS cutoff thresholds. The protection circuit held nominal cutoff at the correct lower voltage limit with no false trips under simulated GPS and radio load.
- Field deployment prep for Recon instruments: After installing, run a full calibration cycle through the instrument menu before going to site. The Recon maps battery state during calibration — skipping this causes premature low-battery warnings to fire during the first active logging session, interrupting data collection at full charge.
BMS lockout after the Recon sat unused in a carry case for months
Ni-MH cells self-discharge over time. If a Recon 200 or 400 has been stored for several months with the original pack still inside, the cells can drop below the BMS recovery threshold — typically under 1.8V total. At that point, the instrument will not power on and the charger shows no activity. The fix is to apply a slow trickle charge at a low current rate through the dock for 20–30 minutes to nudge the cells above the recovery floor. Once the BMS detects sufficient voltage, normal charging resumes and the unit powers on.
Recon shuts down during USB data transfer to PC with battery showing charge
USB data transfer adds a combined draw — active GPS, backlight, and USB bus power simultaneously. On a degraded or freshly installed pack that hasn't completed a calibration cycle, this combined load can cause a momentary voltage sag that trips the BMS low-voltage cutoff. The instrument shuts off even though the indicator shows remaining charge. Run the calibration cycle first so the instrument correctly maps the cell's voltage curve, then confirm the dock charger brings the pack to full charge before initiating any bulk data transfer.