Battery DIY: Kobalt 18v drill battery charger blinks red

[Beebad]

I place the battery on the charger and it is green for about 10 seconds, then flashes red.

I placed the same battery on my kobalt 18-20v universal battery charger and it charges to completion.

Anyone have any ideas on how to service this charger……IT’S NOT THE BATTERY(s). Any ideas?
Thank you.

 

[Moley]

There's not usually a way to 'service' a battery charger. They either work or they don't. You don't say what the other charger is. Is one an 'inteligent' charger and one a 'dumb' charger? If it is then one could be detecting that the battery has a fault and isn't taking a charge properly and stopping the charge and the other is just force charging a faulty battery. How are you so sure the battery isn't faulty?

 

[Beebad]

There's not usually a way to 'service' a battery charger. They either work or they don't. You don't say what the other charger is. Is one an 'inteligent' charger and one a 'dumb' charger? If it is then one could be detecting that the battery has a fault and isn't taking a charge properly and stopping the charge and the other is just force charging a faulty battery. How are you so sure the battery isn't faulty?

There are three batteries. They all charged on the universal charger that came with the drill which i bought within the last two years. I am not even sure the charger on the right goes for these batteries. One thing I know, i will never buy cordless anything again..