A 4.35 drain suspect when testing the charging system.

JSROLLISON

MEMBER
1999 DODGE DAKOTA
3.9L
6 CYL
4WD
AUTOMATIC
172,000 MILES

2 days in a row my battery has been completely dead upon trying to start the truck. Both times I charged the battery and its started fine. I took it to be tested and found out I have a 4.35A short or drain somewhere. Any suggestions would be greatly appreciated.

Battery test results are
Voltage 12.44
CCA measured 619
Rated 600
Temp 63F

Starter Test
Voltage 10.89V
Amps 210.9A
Time 781mS

Charging Test
No Load 14.15V / 10.5A
Loaded 14.05V / 9.6A

Ripple is 44mV

3 Replies

CARADIODOC

MECHANIC
33,723 POSTS

First address the charging problem. Thank you for including the test results. Ten amps is not enough to run the fuel pump and ignition system. Under full load you should be getting well over 110 amps. Since the charging voltage is good, I suspect someone made a mistake either in how they had the amp probe installed or in the numbers they wrote down, but we need to be sure before we go looking for something that might not be there.

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Saturday, November 7th, 2015 AT 5:54 PM

JSROLLISON

MEMBER
2 POSTS

Actually the battery is an 800 cca but looks like its failing. I took the battery compartment apart and discovered the error on the battery rating. It's also over 5 years old. I'm betting my issues are with the battery just losing its charge due to it being old and failing. Your opinions are greatly appreciated.

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Saturday, November 7th, 2015 AT 6:04 PM

CARADIODOC

MECHANIC
33,723 POSTS

If you run into another dead battery / no-start, measure the battery voltage before you jump-start or charge it. A good, fully-charged battery will read 12.6 volts. If it's good but something discharged it, it will be close to 12.2 volts. If it has a shorted cell, it will read around 11 volts or less.

You could be right about a failing battery, but have the full-load charging current rechecked if you continue to have problems. I'd like to see at least 100 amps.

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Saturday, November 7th, 2015 AT 7:05 PM