I have a Silverline Trickle Charger that reads 'Output 12V DC - 500mA'. https://www.amazon.co.uk/Silverline-634004-Trickle-Charger-500/dp/B001C827ZA
I heard the battery bubbling after a few minutes on charge so I took the charger off the battery and put a multimeter across the crocodile clips and the voltage read 20V. I realise that to charge a 12V battery (motorcycle battery in my case) the voltage needs to be a bit higher to overcome the resistance, but this sounds like too much to me, then again I don't know much about electricity.
- Is this charger faulty?
- Am I testing it in the correct manner? or should I test voltage whilst under load on the battery or something?
- Will 20V damage the battery?
- Also, I know how to test amps, i.e inline, but when testing the amps, this should be at or below the 500mA listed?