volts

Isolator Testing

Here is our isolator test page.

Regards

Derek

checked the isolator as per your page. both bats 12.5 car off. both bats 14.2 car at idle

SOC-LINK

Great, here is our state of charge link so you understand battery voltages better.

Regards

Derek

cheers for your help. those links were very easy ,even for a dum ass like myself to understand. looks like the only thing wrong is listening to people who think they know what there talking about compared to those who do..

car is running when i test what the alt is doin. 12.8 is with the car off, i was under the impresion that they should be up around 13.8vlts. the top of the main bat has always had a slight wet look on top of it like there is something leaking on it. I have never had a problem starting the car even on cold mornings.

There is no problem.

If you use your multimeter to probe the voltage at the fattest connection on the alternator when the engine is at a fast idle and no electrical loads, then 14.5v is very good, perfect, maybe a fraction high, but essentially perfect.

If you test your batteries at the same time, they should be close to the same as the output at the alternator. There might be a small voltage drop, 0.3v for example. This is fine. Nothing to worry about.

This means your batteries are receiving the correct charge from the alternator.

Now, you turn off your car. Initially the batteries will drop back a little from 14.2v. This is where the complications of measuring battery capacity, level of charge and the limitations of measuring voltages come into it. There is a thing called a surface charge where the battery shows higher than 12.7v which is the voltage of a fully charged battery. If you leave that battery overnight with nothing connected to it, the voltage will come down to 12.7v all by itself after the surface charge has dissipated. Some people say that running the headlights for a few minutes does the same thing.

A 12v battery never reads 13.5v unless it is being charged. A fully charged 12v battery sits at 12.7v.

I'm not going to go into it any more. It gets technical. There are excellent FAQ on this site, excellent article written by Collyn Rivers and other erudite and competent people on this forum, and others. Have a google search on surface charge, charging 12v batteries, how full is my battery.

What you can stop doing, is worrying about your batterys.

If you want to DO something, go to an auto shop and buy a spray can of Battery Terminal sealer. It sprays yellow or blue goo onto the terminals and stops that wet look, and makes them look really pro. It also sticks to your fingers, but that's another story.

Tim

thanks for help. all good now i can stop worrying just didnt want anything to go wrong when we head to exmouth.

as i mentioned the second bat has a cca rating of 500.
However it dosent have a ah reading on it only rc 90. what ever that means. I find that the second bat runs low a bit quik, i run a fridge and a dvd player for the kids. I find that after a day or so the bat is below 12v which makes the fridge struggle.

make that rc mins 90