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harryzgnilek 08-07-2012 12:25 PM

Normal Battery Drain
Hi all

What is the normal rate of battery drain on a jeep?
After driving my voltage is at 12.7 , one week later at 12.4

is that normal?


harryzgnilek 08-07-2012 01:20 PM


pluke the 2 08-07-2012 02:09 PM

do you have any electrical issues?

heres what my battery looks like :)

harryzgnilek 08-07-2012 02:11 PM

Not really ...just had a compustar alarm starter installed and want to make sure it is not draining the battery at a higher rate than normal


3JKs1H1 08-07-2012 02:32 PM

When you shut the engine off, the battery will go to a resting voltage. If it starts unaided two or three weeks later, you have nothing to worry about.

You can measure parasitic draw with an automotive voltmeter and a shunt (like a used Snap-On MT500)

Here is one:
Snap on tools Precision Diagnostics Meter MT500 | eBay

You hook the resistor(shunt) in series with the battery and measure the voltage across it. (easy to do). If there is a drain, you start disconnecting accessories (or pull fuses) to find the culprit. If your battery dies down in a few days, it'll tell you if it's on a circuit - then you look for a vanity mirror light, door lock solenoid, external amp, car alarm, etc.

harryzgnilek 08-07-2012 02:34 PM

thank you

oilwell1415 08-07-2012 02:36 PM

The voltages you mention are fine.

If you really want to measure the drain you need to disconnect your negative battery cable and install an ammeter between it and the battery. The current draw should be minimal. Anything over .25 amp is questionable and over .5 amp is not good. Most vehicles are under .1 amp.

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