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Parasitic battery drain caused by altenator diodes

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New User

Aug 5, 2018, 5:58 AM

Post #1 of 2 (243 views)
Parasitic battery drain caused by altenator diodes Sign In

2007 Dodge Nitro 125000 miles

The battery goes dead if the car is not started every three days. I understand that it could be the alternator diodes. If I disconnect the alternator lead to the battery will this stop the drain? I am getting 2.25 amps across the battery with everything off. I would like to isolate the problem to the alternator if possible. I am not sure if disconnecting it will help. I have checked the system by pulling fuses one at a time and did not locate a problem.

Hammer Time
Ultimate Carjunky / Moderator
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Aug 5, 2018, 7:58 AM

Post #2 of 2 (233 views)
Re: Parasitic battery drain caused by altenator diodes Sign In

You are not testing it properly.

There is a procedure for finding a battery draw like that.

You will need a digital ammeter and a jumper wire with clips on the ends to do this.
First rig any door switches so you can have a door open without triggering the interior lights and unplug the hood light. Remove one battery cable and attach the meter in series between the battery cable and battery post. Take the jumper wire and also attach it the same way. Leave the jumper wire on for at least 30 to 40 minutes to expire all the automatic timers. Now remove the jumper wire and read the meter. Anything over 50ma is too much draw. The way you locate this is to start removing fuses one at a time until the meter drops to normal level. This will be the circuit with something staying on. Determine what components are part of that circuit and check them individually until the problem is isolated.


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