Drill charger

[MirtSergiu]

I have this bosch al 1130cv 10.8v battery charger. It worked fine until one day when it stopped charging. When i insert a battery, it's charging for 3-4 seconds then the relay closes and it shows the constant green light and when i measure the battery voltage, it shows 8.7v. I took a look inside and i couldnt see anything that doesnt look ok. What could it be?

[aqibi2000]

Common issue is electrolytic caps

[MirtSergiu]

Im thinking that it is recogninzing the battery as fully charged

[tunk]

Or if the battery has a temperature sensor, it could be broken.

[MirtSergiu]

It has a tempereture sensor, but the led should be red it thats the problem

[Slh]

Based on a drill battery and charger (not Bosch) that I've just the same problem with I'd say that one of the cells in your battery is dead.

I presume that it's for 3 series cells of nominal voltage around 3.6V. Fully charged each cell would be around 4.2V so two good cells is pretty close to your 8.7V.

In my case three of the five cells in a 20V pack are charged but two of them are dead shorts and the charger shows the green light for charged. Pack voltage is around 12V as the good cells are fully charged.

[MirtSergiu]

I charged the batteries to around 10.5v with a 12v dc adaptor and tge problem was the same

[Slh]

Do you have more than one battery pack to test it with? There's nothing obvious in the picture that you showed so I'd want to look at the battery.

Alternatively it could just be a dodgy connector or broken wire. You could buzz the wires with a multimeter when it's all disconnected or see if you can measure anything on the battery connections when it's powered on.. I wouldn't recommend probing the charger while it's open so this might not be easy to do. What does it do if you turn it on without a battery connected?

Is there anything on the little PCB  that you're holding in the picture?

[MirtSergiu]

I charged the batteries to around 10.5v with a 12v dc adaptor and i opened their case, tested them and they were all fine. There's nothing on the other side of the small pcb

[aqibi2000]

Just why.