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Melting wire from battery to alternator

Redhanded@kaf

I'm New Here
Hi guys, I'm new to this whole posting to a forum process. Please bear with me.
Here is the issue. Older RV6 has been sitting for a couple of years now.
Working to get flying again. Running fine when parked.
Replaced old battery with new. As soon as I switched on the master switch started to melt the wire to the alternator B terminal (the field power) if I'm understanding correctly. took alternator to a shop where it tested fine. replaced the wire, same result.
Does anyone know what's going on?
 
Sounds like you have a short circuit somewhere along the B wire between where it connects to the power system and the alternator. Suggest you check with a multi-meter (VOM) for continuity (zero ohms) between the wire and ground with the wire disconnected from the alternator and the master turned off. If you see zero ohms to ground, you have a short. I would then inspect the wire carefully along its full length looking for any indications of damaged insulation or other causes of a bare spot contacting ground. You might also disconnect the other end of the wire and check for a short with both ends disconnected, just to be sure that is where the problem is.

I'm not sure what you mean by "started to melt the wire to the alternator B terminal". Is the wire actually melting, just getting hot, or what? Does your alternator have an internal voltage regulator or an external voltage regulator? Providing a bit more information could help us guess what might be wrong.

Good luck
 
B+ and field terminals aren't the same? B+ is the main (big) cable between the alternator and the battery, and the field terminal will have a small wire to the regulator (if externally regulated).

Given that your problem started after a battery replacement, I'd double check that your battery/master solenoid connections are correct - If the alternator B+ cable is connected battery to negative/ground by mistake, then this will cause the B+ cable to get hot (and probably damage the alternator rectifier) after engine start.

If connections are correct, Follow DRMA's advice for testing the cable itself and you'll get there :)
 
Older 6- battery mounted between rudder pedals? Master & starter solenoids mounted between battery & firewall? Check this area for main battery leads (pretty tight fit) grounding to something, might have been slightly moved while changing out battery. Could be grounding to the battery cover box also.
 
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