I have two drills, two chargers, and three batteries. All of the batteries stopped working at the same time, won't take a charge. I've tried both chargers, charging the correct amount of time. Is there anything that would cause that? Seems highly unlikely all the batteries would go bad at the same time.

Your problem states you have a Makita tool and your question is about a Dewalt lithium battery. In either case if the battery won't take a charge or if the charger is showing the battery is defective the only fix is to replace the battery. Some causes for defective batteries or batteries that won't take a charge are bad cells in the battery, bad or shorted IC board in hte battery, broken or burnt connections between the many cells or between the cells and IC board or even bad or old cells that will no longer charge up. The time and effort needed to find out what the problem is then finding another battery to scavenge parts from (individual battery parts are not available) is never worth the cost of just buying another battery and going back to work with the tool(s).

Either the charging adapter is faulty or the battery is worn out.

If the recharageable battery is more than 3 - 4 years old then the battery could be worn out.Rechargeable batteries have a finite number of charge and discharge cycles andwill lose their charge capacity over time, i.e. won't charge to 100% andgradually the charge reduces until the battery won't charge up at all. OR Thebattery shows a 100% charge but when the adapter is disconnected the batterydrops off to zero capacity in a very short time. If the battery drops to anunacceptable charge level then the battery needs to be replaced.

If thelaptop battery is more than 3 - 4 years old then the battery could be worn out.Rechargeable batteries have a finite number of charge and discharge cycles andwill lose their charge capacity over time, i.e. won't charge to 100% andgradually the charge reduces until the battery won't charge up at all. OR Thebattery shows a 100% charge but when the adapter is disconnected the batterydrops off to zero capacity in a very short time. If the battery drops to anunacceptable charge level then the battery needs to be replaced.

I have just had a similar issue I left the drill unused for a period and when i placed it in the charger the charger showed the battery as charged after about 15 secondseconds.

Following a internet search i found a site that suggested for a imlar problem with a camera jump starting the low battery with a 9 v battery. I had a spare from the drill which was fully charged so placed a contact from + to + and - to - and held for about 2 mins. I then placed the battery back in the charger and it started charging. Running the battery down as we speak to recharge again well worth a try. If you dont have a spare maybe the 9 v would work

Directions say green light indicates that the battery is fast charging only,it does not indicate at exact point of full charge. I let my batteries charge for 12 hours for the first time charging,found out myself the same way. Try that and you will notice the difference.

If he light on the charger is off, then your problem is almost certainly the charger. If you can get a working battery from a friend or someone, try that and if the light stays off you've confirmed the charger is bad.

Okay what happens sometimes is the charger gets into a feed back loop. What to do is remove the battery unplug the charger wait a few seconds (Maybe 20/30) plug the charger back into the outlet and then put the battery back in the charger. It should start to charge again and a few minutes later go to the blinking for full charge green.

It'll happen the other way as well meaning if the battery gets a memory (they say they don't but they do) you need to unplug the battery let is sit till it's cool and put it back on charge again. I've had this problem many times and have put it on charge and back off several times with in 15 minutes before it started to charge as it should.

Also these batteries do have a life span and if it's a three year old battery with many charges it could be failing meaning it just won't take a full charge.

One thing I,ve found with cordless tool batteries is that if they're completely dead, the charger won't recognize them. Try hooking a known good battery with a charge up to the problem battery, terminal for terminal, with small jumpers. Leave it hooked up for a minute, maybe a minute and a half. this should be sufficient to provide just enough charge to bring the battery up to the "threshold level" required for the charger to recognize it. Then, simply charge the battery in the normal way. If this doesn't work, you may need new batteries, or a new charger. Hope this helps you.

If the charge count on the batteries is under 300, Makita will replace them. Makita has a known defect in this battery that causes the battery to shut down before it is dead. So as of now they are exchanging ones with low use.

If they are truly defective and makita won't replace, you have to open them, find the dead cell or blown fuse, and replace. Search youtube makita battery for a video on repairing this battery. But once the red and green lights on the charger flash, the the battery can't be charged on a Makita charger -- it's been locked. So use a third party charger.

most likely your inverter is going bad,,,time for a new charger