Battery Charge Testing Incident

Damo gurgled happily, sounding much like they were saying:

I'm no expert, but I can't see how.

The same as for any other nominally 12v car - and that looks about right to me.

Any particular reason you think there's a problem?

Only because i checked the battery a few monthes ago and it was 12.7 volts thats all So was intrigued why the voltage had dropped and wondered if it was this that caused it to drop from 12.7 to 12.4 volts and i dont want to wreck the car or a new battery?

Damo gurgled happily, sounding much like they were saying:

I think somebody's over-worrying...

Cold weather reduces battery voltage considerably, which is partly why this is the time of year that many batteries are sold.

Thanks in advance i probably am over worrying a bit. Ill check again in a few weeks and keep an eye on it

Cheers

Damian

What sort of quality is the meter you used? And is it the same one that overheated?

Within the probable limits of your test equipment, all is well.

Chris

Yes on the same meter Not sure i might get a new one. Had a look in the back of it and no physical damage?

All switching a meter to AC does (effectively) is add in a bridge rectifier. Which will neither damage the meter or what you're measuring. You'll just get a near zero reading.

On the other hand, if you were measuring voltage and changed the meter to measure current, ie amps, and it's the type where you can do this by a switch without having to replug the leads, you'll put a near dead short across things. With the meter set to measure either DC *or* AC current. But a sensible meter has a fuse to prevent damage.

The fuse will most likely prevent damage to the operator, but sadly not always to the meter, or the equipment under test.

In industry, I've seen top of the range Flukes smoked!

Chris

As regards this sort of thing, a fuse will usually protect the meter. Since it's the shunt which is taking the current rather than electronics.

Probably as cheap to replace as a Fluke fuse. ;-)

Yep, on the 10A range; less successfully on low-current settings.

One advantage of working for a multi-national was that we pretty much always had the best tools to do the job.

Chris

Damo used his keyboard to write :

AC volts instead of the DC volts setting, should not cause a spark nor should the meter or car be damaged - it just would not read anything.

Set for AC current it would cause a spark and likely would have burnt out the current sensing section of the meter or perhaps blown its internal fuse.

hey

A few months ago the ambient temperature was higher and therefore will give a higher reading across the terminals. Point three of a difference is ok.

McK.