Testing 12v Car Batteries

Post Date: May 11, 2022

Overview

This is a quick, straight to the point, article on how to test 12 volt car batteries with a Klein Tools digital mm700 auto-ranging multimeter.

Plug the Black terminal into the “COM” jack
Plug the Red terminal into the “VΩ” port
Connect terminals to car battery:
- Negative battery post = Black terminal wire
- Positive battery post = Red terminal wire
Turn multimeter on by setting to: (AC/DC Volts)
- Press the RANGE button until you get to the hundredth place
- Press the SEL button until you get to: DC
Get current reading without the car turned on to find the state of the battery and compare to the state of charge chart

Plug the Black terminal into the “COM” jack
Plug the Red terminal into the “VΩ” port
Connect terminals to car battery:
- Negative battery post = Black terminal wire
- Positive battery post = Red terminal wire
Turn multimeter on by setting to: (AC/DC Volts)
- Press the RANGE button until you get to the hundredth place
- Press the SEL button until you get to: DC
Get current reading without the car turned on to find the state of the battery and compare to the state of charge chart
Turn car Headlights on for 2 minutes (to get rid of surface charge) and take another test
Hit the MAX/MIN button until MIN is on the screen and start the vehicle
Hit the HOLD button so we don’t lose the MIN value
Turn car off
Compare the MIN value with the load test voltage chart

°F	100%	75%	50%	25%	0%
120	12.663	12.463	12.253	12.073	11.903
110	12.661	12.461	12.251	12.071	11.901
100	12.658	12.458	12.248	12.068	11.898
90	12.655	12.455	12.245	12.065	11.895
80	12.650	12.450	12.240	12.060	11.890
70	12.643	12.443	12.233	12.053	11.883
60	12.634	12.434	12.224	12.044	11.874
50	12.622	12.422	12.212	12.032	11.862
40	12.606	12.406	12.196	12.016	11.846
30	12.588	12.388	12.178	11.998	11.828
20	12.566	12.366	12.156	11.976	11.806
10	12.542	12.342	12.132	11.952	11.782
0	12.516	12.316	12.106	11.926	11.756