Keysight U1571A 7.2V 4500mAh Replacement Battery

Keysight U1600 Series — 7.2V Ni-MH Replacement Battery (U1571A)

This is a 7.2V 4500mAh Ni-MH replacement battery for the Keysight U1600 Series handheld digital multimeters, including the U1602B, U1604B, and U1604A. It replaces OEM part number U1571A and restores full portable operation for field service, electrical testing, and survey work. Capacity is sourced from product data at 4500mAh (32.4Wh).

• U1600 Series compatibility: The U1602B, U1604B, and U1604A share the same battery bay geometry, connector pinout, and BMS handshake protocol. All draw from the same 7.2V rail, so this single pack covers the entire series without modification.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on U1600 Series hardware. The BMS reported cell state correctly across the full voltage range, and no false low-battery cutoff occurred during sustained measurement loads.
• Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the instrument menu before field deployment. The U1600 maps battery state during that sequence — skipping it causes premature low-battery warnings during the first measurement session, even with a fully charged pack.

BMS lockout after the U1600 sat unused in a carry case for months

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A U1600 left in a case for several months will often have a pack sitting below the BMS recovery threshold — typically under 5.4V for a 7.2V Ni-MH pack. When the charger sees that voltage, it may refuse to initiate a charge cycle, leaving the pack apparently dead. The fix is a slow precharge: place the pack on the charger, wait 10–15 minutes, then remove and reinsert to trigger a fresh charge detection handshake. If the charger supports a trickle or recovery mode, use it until cell voltage climbs above 6.0V.

U1600 readings drift or reset mid-logging session

During a sustained logging session, the U1600 draws continuous current to power the display, measurement circuitry, and any active probe module simultaneously. Aged or partially discharged Ni-MH cells show significant voltage sag under that combined load, and if the pack voltage dips below the instrument's operating floor, the firmware resets — wiping the current log buffer. This is not a firmware fault; it is a voltage dropout event. Fit a fully charged pack before any logging session exceeding a short field check, and verify pack voltage reads above 7.0V at the instrument's battery indicator before starting.