Slightly OT: Car battery Load Tester

[Andy Smith]

I have a need for a 12V load tester and, being of a certain age, I remember testers something like this type

I'm wondering how the modern digital-type ones like this compare with the carbon pile ones?

Which type is best?

[Fredxx]

I got one like this:

It seems to do the job, I have never used the sort in your link.

[Andy Smith]

Thanks Fred

[The Natural Philosopher]

As I understand it, these do not load the battery excessively to test it, what they do is draw a small current, assume that the batteries internal resistance is constant with much higher currents, and then

*calculate* the Vdrop at cold cranking amps, and if would pull the voltage below some level, flag the battery as bad.

Some people do not regard that as as valid a test as sticking a real heavy load on. But I reckon they work for most purposes.

[misterroy]

Our local place uses something like this:

trust in them.

[Brian]

I have a ‘modern’ one. I’m not entirely convinced they are that accurate.

I tried it on an old battery, which I expected was on its way out, and sure enough the results confirmed my thoughts.

However, the new battery ( a quality one, which I charged) while it measured as good, the readings weren’t that accurate ( CCA that is).

I think I paid about £25 for mine, around 7 / 8 years back.

I’ve not used it since.

When I suspected the motor home battery recently, I just changed it. You can’t bump start a 3.8+ T diesel.

[Animal]

put it in gear & crank, the 3.8t will keep it rolling over the compression points.