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Checking battery amps
matt.c - 14/3/11 at 05:56 PM

How can you check the amps of a battery?

Cheers

britishtrident - 14/3/11 at 06:06 PM

What do you mean ? charge capacity ? cold cranking current ?

Normal way to test a battery is to measure the voltage during a high discharge current test.

Ben_Copeland - 14/3/11 at 06:06 PM

Cranking Amps? Or the amps being drawn from it?

matt.c - 14/3/11 at 06:27 PM

Cranking amps

RAYLEE29 - 14/3/11 at 06:29 PM

Its normally written on the label.
at work we use a meter to check the cca against the quoted figure on the label.
Halfords will test your battery for free.
Ray

matt.c - 14/3/11 at 06:33 PM

Can it be done with a multimeter?

Please make the answer very basic as im useless at using one of them.

iank - 14/3/11 at 07:27 PM

quote:
Originally posted by matt.c
Can it be done with a multimeter?

Please make the answer very basic as im useless at using one of them.


Not directly unless it will take a current clamp. Multimeters only measure up to 10A before popping a fuse, cranking current is around 300A.

More about current clamps here http://autospeed.com/cms/A_111656/article.html

[Edited on 14/3/11 by iank]

alawrence - 14/3/11 at 07:43 PM

yes you can check it with a multimeter
put it on volts and connect to the battery
disconnect your coil so the engine wont start
get somone to crank it over and see what voltage the battery goes down to
10volts would be good bellow 8volts would be bad
thats what i would do..the figure may not be exact but its in the ball park
dont crank it for too long or your starter will over heat

britishtrident - 14/3/11 at 08:08 PM

quote:
Originally posted by alawrence
yes you can check it with a multimeter
put it on volts and connect to the battery
disconnect your coil so the engine wont start
get somone to crank it over and see what voltage the battery goes down to
10volts would be good bellow 8volts would be bad
thats what i would do..the figure may not be exact but its in the ball park
dont crank it for too long or your starter will over heat



That's a volts drop test to do one you have to be sure the battery has 80% charge or more and has been rested off charge for at least a couple of hours.

With no load battery should show at 12.5 to 12.8 volts before test, bellow 12.4 recharge before doing test.
Under starter load if voltage drops
(a) rapidly to 6 volts. = battery has dead cell
(b) rapidly to 6 volts. then rises back to 8 volts = battery has dead cell
(c) slowly from 8 volts. = battery is probably discharge, recharge fully rest battery off charge then and test again.
(a) rapidly to 9 to 11 volts. = battery is probably healthy.

This test only indicates a dead cell it won't indicate reduced charge capacity.