Hey guys just a quick one.

I want to get a car battery tester but don't want to pay the earth but want a decent one for a DIY guy. Does.anyone have any recommendations / tips , tricks all input welcome.

Thanks again

Hi, a bit of theory ?

When a load is applied to a battery, its voltage drops (ie when you crank the engine the lights fade out a bit).

This voltage drop is proportionnal to:
- the current drawn (starter draw more than the wiper motor)
- the battery's internal resistance

A good and well charged battery will have a low internal R, so when loaded a little voltage will drop, that's what the bateery tester does: connect§ a oad to the battery and check the reminent voltage on a voltmeter.

The bigger the battery, the lowest its internal R, so we need different scales (or known values) for different battery power, DIY is coming a bit more complex here ...

BRs, Bernie

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