4.8V Ni-MH Replacement Battery 3600mAh for Homelite UT & Z Series String Trimmers

Homelite UT & Z Series String Trimmer — 4.8V Ni-MH Replacement Battery

This is a 4.8V 3600mAh (17.28Wh) Ni-MH replacement battery for Homelite UT, Z, I, S, and ST series string trimmers. It fits models such as UT‑20626, UT‑20651, UT‑20634, UT‑20634‑A, UT‑20644‑R, UT‑20616, UT‑20616‑A, UT‑20639, UT‑20644, UT‑20618, UT‑20618A, UT‑20640, UT‑20683, I725CE, I725CEA, S825SEV, ST725CEA, Z725CE, Z725CEA, Z725SE, UT20683, and DA06965A. Voltage and capacity match the original specification exactly — no adapter or modification required.

• Series compatibility: These trimmer models share the same battery compartment size, voltage, and connector design — one replacement battery covers the full lineup without fitment issues.
• Bench tested on actual hardware: Full charge/discharge cycles were run — the battery delivered stable voltage under load and maintained output throughout the runtime without overheating or sudden cutoff.
• First use protocol: Fully charge the battery before first use, then let the trimmer run until the low-battery indicator triggers — this helps Ni-MH cells calibrate properly and ensures accurate runtime reporting.

Why capacity matters for string trimmers

String trimmers draw current in short bursts during cutting, rather than a continuous load. A 3600mAh cell bank handles these bursts better than lower-capacity batteries, keeping performance consistent and preventing premature shutdowns. The 17.28Wh rating reflects actual usable energy, not just the nominal cell spec.

Battery not charging — here’s why

If the charger shows an error or the trimmer does not recognize the battery, the cells may have entered sleep mode after long storage. Place the battery on the charger for 10–20 minutes uninterrupted — this wakes the cells and allows normal charging to resume. Avoid removing and reinserting repeatedly, as this can delay the battery’s response.