40V Skil Hedge Trimmer Replacement Battery BY8705-00 Li-ion

My Skil hedge trimmer blade slows down and loses power halfway through a thick section of hedge — is the battery dying or is something else cutting it out?

That's almost certainly the brushless motor controller triggering a load-protection cutoff, not a failing battery — it happens when the 40V pack voltage sags under sustained high-draw cuts through dense wood. The trimmer's electronics read the sag as a fault and throttle output to protect the motor. Let the battery sit off the tool for two minutes, then check the pack's indicator lights — if all cells show healthy, the battery is fine and the issue is cut technique, not capacity. Work in shorter passes through thick branches rather than pushing the full 3/4-inch capacity in one stroke.

New 40V replacement battery won't click into my PWRCore 40 trimmer — it goes in partway but doesn't lock and the tool doesn't power on.

The PWRCore 40 platform uses a keyed slide-rail interface, and aftermarket packs occasionally come with rail tolerances that are slightly wide or have a burr on the latch tab. Check whether the release button on the battery is sitting flush — if it's pre-depressed, the latch spring isn't seating. Clean the rail channel on the trimmer with a dry cloth, then try inserting the battery slowly with firm downward pressure before sliding forward; you should hear a distinct click. If the latch still won't engage, compare the replacement pack's rail width against the original — a 1–2mm mismatch in housing molding is the usual culprit.

Charged my replacement Skil 40V battery all the way, used it for about five minutes of light trimming, and now it's already showing low — why is the new battery draining so fast?

A new lithium-ion pack that drops charge fast on the first few uses almost always needs conditioning — cells shipped in partial-discharge storage haven't balanced yet, so the battery management system reads one low cell and shuts the pack down early even though overall capacity is still there. Run two or three full discharge-and-recharge cycles before judging the pack's real capacity. If capacity doesn't improve by the third cycle, pull the pack off the charger after a full charge and check the voltage with a multimeter at the terminals — a healthy 40V Li-ion pack should read between 42V and 42.5V fully charged; anything below 40V points to a cell not recovering.