battery drain

[kippax]

my batt keeps dying,and light stays on when driving. Had the alt checked and is charging good. If I unplug the harness from the alt. it will hold a charge for days when this cable is not connected. I have replaced batt,batt cablesand the wire to the alt and still no luck. Could it be the starter relay causing this and how can I test for this? 1994 Ranger 4cyl.

 

[cocoasranger]

This could be bad diodes in the alternator allowing a voltage drain when the vehicle is parked. I had two cars that had this; the batteries stayed charged if you pulled the alternator plug when parked just like yours, but drained overnight if you didn't.

I'd have them specifically check the diodes on the alternator since it can still charge to some degree with this defect.

 

[shadetree]

Take a common test light, disconnect your negative battery cable. Hook the light between the cable and the negative batteru post. With the key off, all doors closed, nothing drawing current from the battery, see if the light lights. If it does, you have a drain. Disconnect the wire from the alternator. If the light goes out, the alternator is your problem. If the light continues to burn with the alternator disconnected, you have a drain somewhere else. You can start looking by pulling fuses and see if the light goes out. When you find the fuse that turns out the light, you have found the circuit where the problem lies, then look further from there.shady

 

[exotic_4x4]

i have even seen "loose" starter wires, not enough to make starting the truck an issue, but enought to cause it to drain...also is your truck a manual or an auto? this issue was on a manual turns out it had a loose wire on the starter cylinoid ...i replaced the battery..alternator and the starter until when i was pullin the starter i noticed the loose wire. check it out thats my .02

 

[pruett365]

I've had a similar problem a couple of times, with different vehicles, and for me it turned out that the starter was failing. As soon as my starter went out and I replaced it I noticed the battery would hold a charge.

 

[kippax]

turns out it was bad diodes, to bad the first guy who tested it didn't pick that up. It would have saved me a lot of time and money. Thanks for all the help