About this replacement
Kenwood TK-235A / TH-235 Series — 7.2V Ni-MH Replacement Battery (PB-36, PB-37)
This is a 7.2V, 1000mAh Ni-MH battery replacing the OEM PB-36 and PB-37 packs. It fits the Kenwood TK-235, TK-235A, TH-235, and TH-235A portable transceivers. Same voltage rail, same form factor, same dock connector footprint as the original.
- TK-235 and TH-235 platform compatibility: Both the TK and TH variants in this family share the same 7.2V Ni-MH battery bay and BMS handshake protocol. The PB-36 and PB-37 are electrically identical — only the outer casing differs slightly. This pack satisfies both.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge on a TK-235A dock. The BMS held within spec across PTT transmit bursts, and the charger dock accepted the pack cleanly after the first contact cycle.
- First-insertion contact cycle: 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 Kenwood dock requires a clean contact cycle to complete the BMS handshake before charging begins.
Why the TK-235A cuts out mid-transmission on a new Ni-MH pack
A new Ni-MH cell ships at storage voltage — typically 1.1–1.2V per cell, which puts a 6-cell pack around 6.6–7.2V before its first full charge. During PTT, the transmit current spike can pull voltage below the radio's BMS cutoff threshold, tripping an overcurrent shutoff. This is not a faulty battery. Run one full charge cycle through the dock before using the radio on a shift. After the first charge, resting voltage should read 7.2V or above and mid-transmission cutouts will stop.
Bar indicator showing one fewer bar than expected on a freshly charged pack
The TK-235A uses a simple voltage-threshold bar indicator — it reads pack voltage and maps it to a bar count. A new Ni-MH pack that hasn't been fully conditioned will sit slightly below its rated peak voltage even after one charge, causing the indicator to show one bar short. This is a voltage reading, not a capacity fault. Put the pack through two full charge-discharge cycles and the resting voltage will settle at the top threshold, restoring the full bar display. Check the radio's battery indicator after the second cycle with the radio idle.