Husqvarna 115H 2020 Hedge Trimmer 18V 4000mAh Replacement Battery

Husqvarna 115H 2020 — 18V Li-ion Replacement Battery (584 84 28-02)

This 18V 4000mAh Li-ion battery replaces the original pack on the Husqvarna 115H 2020 hedge trimmer and fits a wide range of compatible Husqvarna 300-series models from the same platform. It outputs 72Wh and connects directly to the existing charger and tool. Capacity figures are taken from product data — 4000mAh at 18V nominal.

• 115H and 300-series platform fit: These models share the same 18V battery rail, physical connector, and BMS handshake protocol. One pack covers the trimmer and any compatible 300-series unit on the same voltage platform without modification.
• Bench tested on actual hardware: We cycled this pack under simulated blade-motor inrush loads. The BMS held stable through repeated high-current start pulses and tripped correctly at thermal threshold — no false cutoffs on normal cutting passes.
• Seasonal storage tip for hedge trimmer use: Before the first cut of the season, bring the battery indoors overnight if temperatures are below 10°C. Cold Li-ion cells carry higher internal resistance, and the blade motor's inrush current on startup can trip the BMS on a pack that hasn't warmed up.

BMS cutoff when trimming thick or wet hedges

Wet or dense branches make the blade motor work harder on every cut stroke. That extra load spikes current draw, and if the spike crosses the BMS protection threshold, the pack shuts down mid-use to protect the cells. This isn't a faulty battery — it's the protection circuit doing its job. Let the pack rest for two to three minutes, then continue with shorter cutting passes to keep current draw below the trip point.

Charger won't accept the pack after it sat unused all winter

Li-ion cells self-discharge slowly in storage. A pack left in the shed from autumn to spring can drop below the charger's minimum acceptance voltage — typically around 10–12V for an 18V pack — and the charger shows a fault light instead of beginning a charge cycle. Most Husqvarna chargers include a recovery mode: hold the battery firmly in the dock for 30 to 60 seconds. If the charger still rejects it, check cell voltage with a multimeter; anything above 10V can usually be recovered by a brief trickle charge before the main cycle begins.