Alternator charging the House batteries

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shearhawk

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Apr 4, 2006
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Sorry for all the questions, as time goes on I find these little problems and I am trying to catch them before they get to be huge problems.  Oh, I am greatful to the feedback, Thanks.  Ok, next question.  My engine alternator charges the starter battery but not the coach batteries.  What is the line of hookup from the coach batteries back to the alternator.  The generator charges the coach batteries fine, but this must be a seperate hook up itself?  Any help?

Thanks,
Randy
 

blueblood

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Joined
Mar 16, 2005
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1,082
shearhawk said:
Sorry for all the questions, as time goes on I find these little problems and I am trying to catch them before they get to be huge problems.? Oh, I am greatful to the feedback, Thanks.? Ok, next question.? My engine alternator charges the starter battery but not the coach batteries.? What is the line of hookup from the coach batteries back to the alternator.? The generator charges the coach batteries fine, but this must be a seperate hook up itself?? Any help?

Thanks,
Randy

This varies considerably by make/model/year. It would help if you'd give that info.
 

Jeff

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Apr 8, 2005
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SD/AZ
Most coaches use the alternator to charge the chassis and house batteries when driving. The house batteries are usually connected through an isolator that prevents running down the chassis batteries with the house batteries while boondocking.

You should be able to find it by tracing the heavy positive lead off the coach batteries towards the alternator, the isolator is a fairly good sized relay in that line. I believe my coach has a large feed off the alternator to the isolator and then splits there, one lead to the chassis batteries, the other to the house set.



 

Gary RV_Wizard

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Feb 2, 2005
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At my Silver Springs FL home
In older coaches ir is not unusual that the engine alternator does NOT charge the house batteries. House batteries may be charged only by the coach's converter, which runs on 120 VAC from either shore power or generator.

You can jumper the coach batteries to the chassis (engine) battery to get charging but there are a couple caveats. The big one is to disconnect the jumper when boondocking, cause you don't want to run the chassis battery down and be unable to start the engine. Or install an isolator, which lets the current flow onlyone way and prevents discharging of the chassis battery. The other caveat is that you really should not allow both the alternator and the converter to try to charge the same bateries at the same time.  Mostly it's just ineffective, but there are situtaions where the converter - or possibly ebven the alternator - could be damaged if they both are fighting to push electricity into the batteries. Best if this is avoided.

Newer coaches have a fairly complex set of relays that make sure only one charging source is actively charging the batteries at one time. You may have this set up but it is not working - one of the relays is non-functional. However, my bet is that a 91 Coachman simply does not atempt to charge from the alternator.
 

Jeff

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Apr 8, 2005
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Gary:

Our 71 Glastron and  72 Starcraft simply tied the batteries together to charge them while  driving. Our  83 Pace Arrow, and 98 Pace Arrow used isolators and charged the house batteries.

My guess would be most m/h's were using isolators by 1991.
 

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