Battery Drain 72 K10

[WPPT]

We have been trying to find cause of battery drain on my 15 year olds 1972 K10. Changed alternator, found some exposed wires, but can't remedy. Looking into the regulator, but can't see one I recognize. Is the part in the picture a regulator? New territory for us.

[71swb4x4]

The regulator is on the driver's side of your core support by the horn.

Do you know how to isolate drains? Use a test light and unhook things to isolate them. I can type it out but I will find you a good thread instead.

[71swb4x4]

This thread will get you started: http://67-72chevytrucks.com/vboard/s...d.php?t=546968

Basically disconnect a battery cable. Use the test light to bridge the gap between the just disconnected cable and the battery. If you have a draw your test light will be lit. Disconnect items until it goes out. If you are working with your truck door open pull the dome light or that will show as your draw.

[WPPT]

Thanks. Have tried to find the drain with the test light but no luck, Will continue. Do not see any regulator on the driver side where I would expect it. The part in the pic is on the passenger side firewall.

[71swb4x4]

Do you have an internally regulated alternator? That is a very common, and good, upgrade that many truck owners make.

Edit, this thread has a picture of a stock regulator: http://67-72chevytrucks.com/vboard/s...d.php?t=426231

[WPPT]

Thanks. That is the part I have searched for, but do not see one.

Altenator is NAPA 213-4020 I believe it is externally regulated. Wonder if I am needing an internally regulated one.

[WPPT]

Previous alternator was smaller and we were replacing it for a bigger one. Thinking we found the drain problem was the first alternator as it tested bad when we took it in for core. Old one had a plugin connection, did not match new one. Ran wires straight to new alternator.

[WPPT]

Found papers on previous alternator. NAPA 213-4011. This one the one on the truck when we got it. It was an internal regulated altenator. By replacing it with the external regulated model I am sure that is why the drain is occurring now.

[57taskforce]

If you get the wires in the plug on the alternator crossed it will drain the battery when not running and over charge the system when running. My truck was wired like this when I got it and it would kill the battery over night. However if you had an internal regulated alternator in it before and you swapped for an externally regulated unit, and you can't find the original external regulator I'd say you've got other problems. In order to bypass the external regulator,(to run an internally regulated alternator) you have to either splice or jump the wires at the external voltage regulator harness plug. If you've gone back to an external regulator you'll have to undo that as well as hook the regulator back up. Maybe post up some pictures of what you've got and we can better help figure it out. Member vettevet is the forum wiring guru, he is really knowlegable at this stuff. I converted mine to a 10si internally regulated unit and it works great, no issues at all.

[WPPT]

Thanks, Thinking I will get an IR alternator and put it in. Did not even think about it when we changed alternators.

[71swb4x4]

It sounds like you found your problem. Nothing a couple of wrenches can't fix. Hopefully the parts store will let you return the alternator.