Grinder battery won't charge? Need help!

Hey everyone, new here. I've got a cordless angle grinder (Makita 18V) and the battery just won't charge. It's about a year old, I use it occasionally. I plug it in and the charger light stays red, no blinking, nothing. Tried a different outlet, still nothing. Any ideas?

Welcome to the forum. First thing, check if the battery terminals are dirty or corroded. Sometimes they get a film on them. Clean with a pencil eraser or some contact cleaner. Also, make sure the charger contacts are clean. If that doesn't work, try a multimeter to see if the battery has any voltage left. It could be the charger is bad, but more often it's the battery protection circuit. Have you dropped the battery recently? That can trip the protection.

I'd also check the fuse in the charger if it's the type with a fuse. But more importantly, safety first: if the battery is swollen or damaged, don't mess with it. Dispose of it properly. Also, some chargers have a reset button or you have to hold the battery in a certain way. Check the manual. If it's under warranty, contact Makita.

I had this happen with a Dewalt battery once. Turned out one of the cells died. I just popped open the case and replaced the cell. Not for the faint-hearted though. If you're not confident, just buy a new battery. But if you're on a budget, it's a fun DIY project! Just be careful not to short anything.

Thanks for the tips! I'll try cleaning the contacts first and check the voltage. I heard the warranty might be over, but I'll see. If all else fails, maybe I'll try the cell replacement, but I'll watch some videos first. Appreciate the help!