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Author Topic: Another electrical question  (Read 525 times)

Sailorkane

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Another electrical question
« on: April 16, 2017, 09:54:54 AM »
2003 Journey.  12V system.  Trombetta battery connect solenoid is up front.  Two connections on the trombetta:  one for house, one for chassis batteries.  And a control wire to combine them, which is off.  My understanding is that when the alternator is charging the chassis battery, the trombetta is supposed to close and connect the house and chassis batteries to allow house batteries to charge from the alternator.  Last October, the trombetta failed and I replaced it with another identical one.
Last trip, the house battery discharged while driving.  So I thought the trombetta had failed.  Right now, strange voltage readings that I can't figure out.  We are parked in RV park with external 120V connected (but same readings when shore power is turned off).  At the batteries themselves, chassis is 12.6, house is 13.4.  At the Trombetta terminals, house is 13.4, chassis is 13.4.  I can't reconcile the difference in voltage readings of chassis batteries at the battery and at the trombetta.  All readings with engine off.
Any thoughts?
I had intended to add a dual voltage sense relay to combine the batteries to replace the trombetta that I thought had failed.  But the readings make no sense and until I know whats happening, I'm reluctant to do anything.
2003 Winnebago Journey DL 39WD, Freightliner, Cat 3126E 330HP.  Diesel Pusher.

John Canfield

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Re: Another electrical question
« Reply #1 on: April 16, 2017, 12:12:10 PM »
Do you have a Trik-L-Start (or equivalent) installed to charge the chassis batteries while on shore power?
--John
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Alfa38User

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Re: Another electrical question
« Reply #2 on: April 16, 2017, 12:24:25 PM »
Is it possible that the Trombetta relay has its contacts stuck or welded in the operated position so the house battery reading appears on both sides? Try tapping on it and see if anything changes.
Stu
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Mile High

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Re: Another electrical question
« Reply #3 on: April 16, 2017, 12:45:11 PM »
They are easy to test - the smaller set of wires is the switching circuit.  Disconnect the positive side of the switching circuit and if already energized, touch it up against it's post to hear the solenoid click.  If you don't hear anything chances are it went bad.   It is rare for these to fail however.
Brad and Dory
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Charlie 5320

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Re: Another electrical question
« Reply #4 on: April 16, 2017, 06:12:56 PM »
Take a reading across the small terminals and see if it has power. If your coach has a bird system it may be operating like it's supposed to. Unplug your coach and take the readings again.
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John Canfield

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Re: Another electrical question
« Reply #5 on: April 16, 2017, 06:59:23 PM »
It's not a BIRD, just a dumb solenoid.
--John
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Lou Schneider

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Re: Another electrical question
« Reply #6 on: April 16, 2017, 09:39:02 PM »

Last trip, the house battery discharged while driving.  So I thought the trombetta had failed.  Right now, strange voltage readings that I can't figure out.  We are parked in RV park with external 120V connected (but same readings when shore power is turned off).  At the batteries themselves, chassis is 12.6, house is 13.4.  At the Trombetta terminals, house is 13.4, chassis is 13.4.  I can't reconcile the difference in voltage readings of chassis batteries at the battery and at the trombetta.  All readings with engine off.
Any thoughts?

It sounds like you have a bad connection between the chassis battery and the Trombetta.

If you're reading 13.4 volts at Trombetta end of the chassis battery cable and 12.6 volts at the battery end of the cable, that says there's a problem between the Trombetta and the chassis battery.  I'd look for a loose or corroded connection, or possibly a push-to-reset circuit breaker that's tripped.

When you're driving, the charging voltage goes the other way - from the engine alternator to the chassis battery, then from there through the Trombetta to the house batteries.  Again, a bad connection between the Trombetta and the chassis battery will stop the alternator's charging voltage from reaching the Trombetta and the house batteries.
« Last Edit: April 16, 2017, 09:55:58 PM by Lou Schneider »

John Canfield

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Re: Another electrical question
« Reply #7 on: April 17, 2017, 06:56:26 AM »
I neglected to mention the voltage difference between the solenoid terminal and the chassis battery itself could be due to the little solar panel driving up the voltage at the solenoid.
--John
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Ernie n Tara

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Re: Another electrical question
« Reply #8 on: April 17, 2017, 08:19:16 AM »
In his other post on this he states that the chassis battery is 12V and both sides of the Trombetta are at 13.4V. Its not the solar panel! Mistaken readings?

Ernie
Ernie 'n Tara

2011 Winn Journey 34y
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