About this replacement
Ryobi RY40210 / RY40200 Series — 40V Li-ion 9.0Ah Replacement Battery (OP4026A)
This is a 40V lithium-ion battery rated at 9000mAh (360Wh), built to fit the Ryobi 40V platform. It slots into the RY40210 and RY40200 string trimmers, the RY40610 and RY40600 blowers, and 76+ additional Ryobi 40V tools sharing the same battery rail and BMS handshake. OEM part numbers covered include OP4026A, OP4026, OP4030, OP4040A, OP40501, and related variants.
- 40V platform compatibility: Every model in this fit list runs the same 40V rail, uses the same keyed slide connector, and expects the same BMS communication signal from the pack. That shared architecture is why one battery covers string trimmers, blowers, and mowers across the range.
- Bench tested on actual hardware: We ran this pack on a RY40210 trimmer head under continuous load. The BMS held the voltage rail stable through repeated motor-start inrush spikes and engaged overcurrent protection cleanly without nuisance trips at normal throttle.
- First-use break-in on string trimmer: On the first two charges, run the trimmer at half throttle through light grass before pushing full-speed cuts through thick brush. This lets the BMS log the motor's inrush current signature and set accurate overcurrent thresholds before you hit heavy vegetation.
BMS cutoff on trigger-pull inrush during thick-brush cuts
When the RY40210 trimmer head bites into dense material, the motor draws a short inrush spike that can be three to five times the steady-state current. If the BMS has not yet profiled the motor's inrush pattern — common with a new or freshly charged pack — it may read that spike as a fault and cut power immediately. The fix is to let the BMS accumulate a few normal-load cycles before demanding peak torque. After two or three standard cycles the protection threshold settles around the tool's real operating envelope and nuisance cutoffs stop.
Charger not recognising the pack after long storage
A 40V Li-ion pack sitting unused for several months can drop below the charger's acceptance threshold — typically around 30V. When cell voltage falls that low, the Ryobi charger sees the pack as defective and either blinks red or shows no response at all. To recover the pack, connect it briefly to the tool and pull the trigger for two to three seconds; this draws a small load that can bump cell voltage just enough for the charger to accept it. Once the charger begins a normal charge cycle, confirm the LED moves to solid green within the first 30 minutes — if it stays red, cell voltage is below 25V and recovery is unlikely.