My Cordless Vac Won't Charge - Help!

Hey all, newbie here. Just got a cordless shop vac from a garage sale, looks almost new but the battery won't charge. Plug it in, light comes on for a sec then goes red. Any ideas? Is it the battery or the charger?

Sounds like the battery might be deep discharged or just dead. Some chargers won't revive a battery that's been drained too low. Try leaving it on the charger for a few hours, sometimes it kicks in. If not, check the charger with a multimeter if you have one. Could also be a bad cell in the pack. Might be cheaper to just replace the battery if it's a common brand.

Don't go buying a new battery right away! Check if the charger works with another battery if you can borrow one. Also, some aftermarket batteries are cheap, but sometimes you can rebuild the pack yourself if you're handy. But honestly, for a garage sale find, might not be worth the hassle. You can get a good corded vac for $30 that'll suck harder anyway.

Yeah, what Dan said about deep discharge. I had a similar issue with my drill battery. I used a 'jump start' trick by connecting it to a good battery in parallel for a few seconds to give it a jolt. But be careful if you try that. Also, check the contacts on the battery and the tool - sometimes corrosion. If it's a known brand like Dewalt or Ryobi, look up the specific issue. Sometimes the charger has a reset button or you have to press the battery in until it clicks.

Thanks everyone. I'll try the multimeter and maybe look for a used battery. It's a Black+Decker, not high end, but I got the whole vac for $10 with a bunch of attachments. Might just buy a new battery if it's not too much. Appreciate the help!