Upgraded to a 200 amp alt and it has a small pull on the batteries

[kfrosty]

I know it's just the alt. In particular it's the large charging wire from the alt to the starter. If I remove that then the draw stops.

Otherwise, the alt seems to work good. It will do it if no other wires are hooked up but just the positive charging wire.

All that changed was the alt and the problem wasn't present before the alt.

My only test is I noticed it after hooking everything up and putting the positive wire back on the battery. You get a tiny spark when it touches the battery post. Then I started unpluging wires until it doesn't do it anymore.

I haven't used anything to see how much the draw is but know it's there now.

Thoughts as to why that would be the case? Alt is not new but was pulled from a working engine.

 

[NDT]

How is the excite wire connected to the new alt? The one that used to go to the 60 amp?

 

[kfrosty]

568A or 2A?
Per the instructions, 2A goes to the Acc on the new alt. A 568 connector plugs into 568A and connects Ign.
568A is the wire on the old alt that is soldered on.

The other wire, 2A connected to the alt. with a ring terminal.

The way I have it now is the only way everything works


But regardless without those wires even connected, why would just connecting the large gauge charging wire from to the starter cause draw.

 

[dmetalmiki]

I believe, Because there is (should be(a functional))diode in the circuit to prevent current flowing back into the alternator(?).

 

[kfrosty]

Where would the diode be? Are you saying it would be in the alt itself and is possible bad or not functioning? ​

 

[Stein12501]

I bought a 200 amp alt for a replacement on a hmmwv and mine does the same thing. I called the supplier back and he sent me a known good regulator. I replaced it and still have the same problem. Someone on the site said that he had the same thing and it was some of the diodes were bad. I leaning towards that being the problem. The next thing I found that the front bearing is going bad in the alt, so I might as well bite the bullet and do both. Good Luck and let me know if anything works for you.

 

[dmetalmiki]

Where would the diode be? Are you saying it would be in the alt itself and is possible bad or not functioning? ​

Inside the alternator itself. That is usually a symptom of the fault you describe. A simple fix usually. Sometimes it is caused by connecting the alternator up incorrectly.
Years since I did one (or the theory) but I believe there are 3 diodes protecting the circuit.
A competent auto electrician will test and repair (replace) if it checks out to that limited fault.
Here is a wee bit of theory for you to mull over.

The alternator is the heart of the charging system. It generates all the power needed to keep the battery fully charged and to operate everything electrical in the vehicle. The alternator is mounted on the engine and is belt-driven off the crankshaft pulley by a serpentine belt or v-belt. The alternator produces alternating current (AC), which is converted to direct current (DC) by a six diode rectifier, which is usually located inside the back of the unit. Diodes only pass current in one direction, which is how they convert AC current to DC. Three positive diodes control the positive side of the AC sine wave, while three negative diodes control the negative side.
The alternator's charging output increases in proportion to the electrical load on the charging system and engine speed. Output is low at idle and increases with RPM. Maximum output is typically achieved at speeds above 2,500 RPM.