36V Wolf Garten GTB 36 Compatible Battery 3.0Ah Li-ion

My Wolf Garten GTB 36 trimmer starts fine then bogs down and loses power mid-job — is that the battery dying or something else?

That's voltage sag under load, and it happens faster with a 1800mAh pack on a 36V trimmer than most people expect — the cell capacity is low enough that hitting thick grass or dense growth pulls the pack below the tool's cutoff threshold quickly. Check whether the trimmer recovers after a 2-minute rest; if it does, the cells are depleted, not faulty. If it doesn't recover at all, put a multimeter on the battery terminals — a rested, charged pack should read at least 36V, and anything under 32V means the cells have degraded past useful range. Try clearing the cutting head of any wrapped grass first, since a jammed head creates enough extra draw to trigger the same symptom even on a healthy battery.

Wolf Garten charger finished the green light but the trimmer still feels weak — did the battery not actually charge fully?

A green "done" light on Wolf-Garten chargers indicates voltage has been reached, but it doesn't confirm the cells balanced across all groups — a pack with even one weak cell group will show full on the charger and still deliver weak torque under load. Pull the battery off, wait 10 minutes, then put it back on the charger; if it immediately shows green again without any charge cycle, the charger isn't seeing a problem the cells actually have. Run the trimmer until it cuts out, then measure terminal voltage immediately — if it reads below 30V straight off a "full" charge, one or more cell groups have collapsed. A healthy pack pulled from a completed charge and lightly loaded should hold above 33V.

GTB 36 battery gets warm really fast and the trimmer shuts off — is that normal or is something wrong?

Li-ion packs at 1800mAh have less thermal mass than higher-capacity packs, so they warm up faster under the same load — but shutting the tool off is the battery management system tripping over-temperature protection, which is not normal operating behavior. The most common cause on grass trimmers is a partially blocked cutting head forcing the motor to draw more current than the pack can sustain cleanly. Clear any grass wrap from the spool and head, let the battery cool to room temperature, and retry on light grass — if the shutdown still happens within a short burst, the BMS is reacting to a genuine cell temperature problem and the pack needs replacing. Feel the battery immediately after shutdown; if it's hot to the touch rather than just warm, that confirms thermal protection triggered rather than a low-charge cutoff.