Testing a 20v tool charger

[wantacoe]

I am trying to check if it is the battery or the charger that is bad. I can get decent reading on the battery but when I test the charger with a multi meter it doesn't work. I have other brands of batteries and chargers and they do the same thing, batteries check out fine but not the chargers? I know to use 200 when testing. What am I doing wrong? TIA

 

[Nobody-named-Olli]

Tool chargers & batteries (as well as tools) of quality manufacturers “communicate” with each other. The charger will only charge when it determined it is safe to do so. Your test leads hooked to + and - are missing the communication part, so the charger doesn’t “charge”.

Kind regards,
Olli

 

[bwringer]

Yup, the charger and battery need to talk first before any electrons are doled out. A multimeter won't tell you anything useful about the charger.

Honestly, the only success I've had in this endeavor is by trying the same battery in a known good charger (or try known good batteries in the suspect charger). If you're halfway deep into any given battery religion, you probably have more than one surplus charger lying around thanks to bundle deals.

I suppose you could also open up the charger and look for obvious issues, but I've never really spotted anything this way.

I've gotten some good deals and even free tools and batteries thanks to bad chargers leading people to condemn the battery and/or give up on the tool.