Help! My angle grinder battery won't charge

Hey guys, I've got an 18V angle grinder (Makita, 4-1/2") and the battery won't charge anymore. I've had it for about a year and it's been working fine until now. I've tried two different chargers, and the light just blinks red. Is it toast or can I revive it?

Could be a dead cell or the battery management system is tripped. Try putting it on the charger and leaving it for 10-15 min, sometimes the BMS resets. If not, check the contacts on the battery and grinder for corrosion. If they're dirty, clean with contact cleaner. But if it's still blinking, it might be time for a new battery. Also, make sure you're using the correct Makita charger - some knockoffs can cause issues. Safety first, don't try to open the battery unless you know what you're doing.

Before you toss it, see if you can get it tested at a local tool repair shop. Sometimes they can re-cell a battery for cheaper than a new one. But honestly, for the price of a new Makita battery, I'd just grab one on sale. Also, check if your grinder was recalled - some had battery issues. And if you're gonna get a new one, consider the 5Ah ones for longer run time.

Same thing happened to my old drill. Ended up being a broken wire inside the battery pack. If you're handy with a soldering iron, you could open it up and see. But I'd only do that if it's out of warranty. I've re-celled a few batteries myself, saved a bunch. But if you're not comfortable, just buy a new one. Also, make sure you store batteries at room temp, cold kills them.