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Topic: Alternator not charging (Read 456 times) previous topic - next topic

Alternator not charging

Just after I left for Whistler last night I notice the alternator wasn't charging. Returned
home and was going to call it a night and then I thought do a quick troubleshooting.
Took a test light to the two small posts on the alternator and there was no juice at one
of the posts so I took a light jumper from the isolator to that post and the alternator
started charging so I took off for Whistler. Today after skiing I took the lead of the
alternator and hook up my tone tracer and found a corroded out terminal on a breaker.
Cut the wire back and put a new terminal end on the wire and I'm good to go. I would
love to go out and have no issues.

Re: Alternator not charging

Reply #1 –
Sounds like the alternator EXCITE wire.  Should be HOT when ignition switch is ON.

Re: Alternator not charging

Reply #2 –
No it was the sense wire and is hot all the time. I wasn't sure which one it was until
this afternoon when I check the other one with the key on and off and it turn on and
off. Last night as I didn't know which one it was I only put the jumper on when the
engine was running.

Re: Alternator not charging

Reply #3 –
The alternator should put out some kind of charging current with or without the SENSE wire connected.

The SENSE wire only increases the charging voltage slightly to compensate for voltage loss across the diodes in the isolator.

Re: Alternator not charging

Reply #4 –
Foretravel connected the start battery sense wire to a breaker on the inverter panel. This has caused many problems over time. We ran a small (like #12 or 14) fused wire from battery positive terminal across the frame in a PVC pipe and over to alternator.  Alternator wants to know battery voltage and the best measurement point is directly from battery terminal.

Re: Alternator not charging

Reply #5 –
I agree Chuck but that is the way it works, I thought when there was no sense wire
the voltage went wild.. On my coach there is 2 breakers in series which makes no sense
to me.