Midland MPA1200 SP130 Replacement Battery 7.2V 1800mAh

Midland SP130 / SP140 / SP150 / SL55 — 7.2V Ni-MH Replacement Battery (MPA1200)

This is a 7.2V, 1800mAh Ni-MH replacement battery for the Midland SP130, SP140, SP150, and SL55 handheld two-way radios. It slots into the same battery bay as the original MPA1200, MPA1400, MPA1800, and MPA600 packs. Capacity is rated at 1800mAh (12.96Wh) — drawn from the product specification, not estimated.

• SP130 / SP140 / SP150 / SL55 platform fit: These four models share the same battery bay geometry, contact pin layout, and 7.2V voltage rail. The BMS handshake threshold is consistent across the range, so one pack covers all four radios without modification.
• Bench tested on actual hardware: We ran this pack through full charge and PTT-load cycles on the SP130. The BMS held stable under the transmit current spike and did not trip into overcurrent cutoff during sustained key-down sequences.
• Contact strip seating on first insertion: Ni-MH cells ship at storage voltage. If the charger dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The dock needs a clean contact cycle to accept the BMS handshake before it will begin charging.

Why the SP130 drops to reduced TX power mid-shift on a new pack

Ni-MH cells leave storage at roughly 60–70% of rated voltage. Under sustained RF output, that lower starting voltage sags further, and the radio's power management circuit steps down transmit power to stay within its operating envelope. This is not a faulty battery — it is the radio protecting its RF stage from an undervoltage condition. A full conditioning charge cycle restores the cell to its rated 7.2V and eliminates the sag. After one complete charge, TX power returns to full level and holds steady across the shift.

Bar indicator showing one fewer bar than expected after charging

The SP130 uses a voltage-threshold bar indicator — each bar corresponds to a voltage step, not a percentage read from a chip. A new Ni-MH pack often peaks slightly below its final resting voltage immediately after the first charge cycle ends. Pull the pack from the dock, leave it for 10–15 minutes, then reinsert — the resting voltage settles upward and the indicator typically recovers the missing bar. If it does not recover after a second full charge, measure the pack voltage directly; a healthy cell at full charge reads at or above 7.2V.