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RV Charging problem


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JSutton1
New User

Oct 8, 2013, 8:54 AM

Post #1 of 4 (1247 views)
RV Charging problem Sign In

Good morning,

I have a pretty unique question concerning the charging system in a 80’s era rv.

Some background.

Diesel rv with Lestek High Amp Alternator (new rebuilt) with Transpo external regulator.
Three extremely big batteries, old but not bad as much as I can tell.
Isolator separating one of the batteries from the other two.
The signals from the regulator to the alternator all seem good including the field at 11 volts.

My problem.

At idle I am only seeing 12 volts at the batteries and ammeter is roughly 0, not charging, not discharging. When I rev up, then the voltage increases and the amps goes up.

Why only 12 volts at idle? What can I do to test this? I think should be 14 volts at idle and should not be a problem for this alternator rated 125 amps.

Jim


Tom Greenleaf
Ultimate Carjunky / Moderator
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Oct 8, 2013, 9:23 AM

Post #2 of 4 (1232 views)
Re: RV Charging problem Sign In

? 1980s. Check as you probably did all connections at alternator and regulator AND for any hacked wiring. Can't help a bit with the brands mentioned and don't want you to make any extra problems but you should be able to ground field and see a spike in voltage just for a test if the issue is at the alternator itself. If attempted just for a split second.

RV, boats, yachts (did tons of that crap) same deal if 12v systems. It should show same voltages you see on cars or trucks. Yes if all is just ducky 14v while running with batteries charged up or close after a start with good batteries. May settle lower.

What to do? Get alternator tested if you can easily. If you don't have one get a battery maintainer for this thing unless you use it a lot those batteries are expensive and will croak if not tended to and the isolated one (great idea) too. If you leave this plugged into 110 current when parked it should do that by itself I would think?

If this sits a lot it could just be brushes in the alternator not making a good contact. If you are clever and have a clue can take it apart yourself or send it out if needed and get your own fixed not some exchange for another unless really wrecked somehow.

If you don't know of a place that does do their own alternator, starters and such locally ask an RV dealer or even an auto parts place where or who does that stuff. They exist,

T



nickwarner
Veteran / Moderator
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Oct 9, 2013, 1:13 AM

Post #3 of 4 (1216 views)
Re: RV Charging problem Sign In

Wouldn't hurt to do a voltage drop test on the power wire from the alternator to the battery. Its old enough that if it gets corroded internally you won't get much amp flow.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Oct 9, 2013, 1:45 AM

Post #4 of 4 (1212 views)
Re: RV Charging problem Sign In

Re-read and a quote from top ">>At idle I am only seeing 12 volts at the batteries and ammeter is roughly 0, not charging, not discharging. When I rev up, then the voltage increases and the amps goes up. <<"


Jim,

What is this RV and model year? Saying it has 3 batteries suggests it has a lot of creature features and custom wiring in general all thru the thing not always so well done IMO from new on many.

No clue how you are testing but you said there it doesn't charge at idle by volts but does increase volts when revved up some. How you are testing for amp output escapes me so far.

It does something and might just be fighting very low charge on batteries?? All wiring suspect at this point at Nick pointed out but you still need to begin with known good and charged up batteries.

Rebuilt parts doesn't mean anything as they can fail instantly or wasn't checked much and just looks good so discount that for now and why did you change it to begin with?

T







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