18V Gardena Accucut 400Li Compatible Battery 2600mAh

My Gardena Accucut cuts fine for a bit then suddenly stops and won't restart until I wait a few minutes — what's wrong?

That's thermal cutoff triggering, and it's working as designed — but it shouldn't be happening this fast on a healthy battery. Li-ion cells at this capacity class heat up quickly when they're pushed through thick or wet grass, and an aged or undersized pack hits the cutoff threshold sooner than a fresh one. Let the trimmer cool for three minutes, then check whether it restarts at full speed or sluggishly — sluggish restart points to a pack that's lost usable capacity, not just heat. Put the battery on the charger after it cools and see if it accepts a full charge cycle without faulting.

My replacement battery fits in the Accucut but the trimmer runs noticeably slower than it did with the original — is something wrong with the new pack?

A new 18V Li-ion pack running the trimmer slower than the old one usually means the cells aren't delivering full voltage under load — the resting voltage looks fine, but it sags when the motor draws current. We see this on bench tests when a replacement pack has higher internal resistance than the original, either from mismatched cells or a pack that wasn't properly balanced before shipping. Pull the battery off the trimmer immediately after a short run and check the surface temperature — a pack with high internal resistance runs noticeably warmer than it should. If you have a multimeter, check terminal voltage under load; it should stay close to 18V and not drop toward 15V or lower mid-cut.

The charger light just stays solid or keeps blinking and never goes green — the battery came straight out of the box like this

A brand-new Li-ion pack can arrive in a deep discharge state if it sat in a warehouse for months, and some chargers won't start a normal charge cycle when they detect voltage below their minimum threshold. Leave the battery on the charger for 20 minutes without touching anything — some chargers run a slow recovery pulse below the main charge threshold before switching to normal mode. If the light pattern doesn't change at all after 20 minutes, remove the pack, wait 60 seconds, and reseat it firmly to rule out a contact issue. If the charger still won't accept it, check the battery terminals for debris or oxidation and try the pack in a second compatible Gardena charger if one is available.