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 > Need help replacing charging circuit solenoid.

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enblethen

Moses Lake, WA

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Posted: 01/16/20 06:47pm Link  |  Quote  |  Print  |  Notify Moderator

In dualmode the two battery system should be tied together for charging.
In dual mode there should be power to the small post of the relay.
To test put switch in center position. Measure voltage on the large terminals should be different. Have helper hold switch in mom position the relay should energize and measuring voltage on large terminals it should be the same. If it is not bad relay.
If yes, put switch in dual mode. Relay should energize and voltages should be the same.


Bud
USAF Retired
Pace Arrow

2003 Chev Ice Road Tracker


maillemaker

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Posted: 01/17/20 06:43am Link  |  Quote  |  Print  |  Notify Moderator

Dual Mode should only energize when the ignition is on though.

Again, I think this is the key I was not understanding before.

All the solenoid does is gang the two batteries together, MOM or DUAL it is the same.

The difference is where the power source comes from to energize the solenoid.

With MOM, it comes from the house batteries.

With DUAL, it comes from the ignition switch (engine batteries).

The reason is because in MOM it is assumed the engine battery is dead. And by making the switch spring loaded, you can't permanently gang the batteries together and pull down the house batteries.

In Dual, you want to charge, so the rocker "sticks" in that position, but you don't want to use your engine battery as a house battery (and risk draining your engine battery) so the solenoid disengages when the ignition is off, thus isolating the engine battery.

Before this thought exercise, I was assuming there were two different ways of achieving the ganging together of the house and engine batteries. In reality, there is only one way. The Charging Solenoid gangs them together. The only difference is who is energizing the solenoid.

Steve


1990 Winnebago Warrior. "She may not look like much but she's got it where it counts!"



enblethen

Moses Lake, WA

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Posted: 01/17/20 07:50am Link  |  Quote  |  Print  |  Notify Moderator

Not sure of your circuit board design. On my rig the chassis battery needs to reach a voltage value before the charge relay is energized.

enblethen

Moses Lake, WA

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Posted: 01/17/20 08:04am Link  |  Quote  |  Print  |  Notify Moderator

Do you have an Owner's manual?

Owners manual

ksg5000

Oregon

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Posted: 01/17/20 08:34am Link  |  Quote  |  Print  |  Notify Moderator

maillemaker wrote:

Quote:

The momentary switch is for temporary tying system together for emergency start.
The dual function is for charging the batteries.


Yes, I understood that much previously. But I thought there was some special or separate circuit for ganging the batteries together for charging vs. for boost.

If I understand correctly now, both ways the batteries are ganged together the exact same way.

The only difference is how the solenoid is switched on.

In the Dual position, the solenoid is only energized if the ignition is on. This way the batteries will not be ganged together if the engine is off, so your chassis battery cannot be depleted by running house things.

In the Momentary position, the solenoid is energized from the house bank, whether the ignition is on or off.

But in either case, the effect is to gang both batteries together. The only difference is which power source energizes the solenoid.

Does that sound correct?

Steve


Yep - the momentary switch is powered by the house battery


Kevin

maillemaker

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Posted: 01/17/20 10:57am Link  |  Quote  |  Print  |  Notify Moderator

Yes, I have an owner's manual, thanks. A digital one is always nice to have also.

I think I have a basic understanding of how the charging/isolation circuit works now.

I agree this should have nothing to do with chassis system voltage so my whacking on the solenoid was just luck.

I'll have to do some more investigating.

Steve

BFL13

Victoria, BC

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Posted: 01/17/20 06:24pm Link  |  Quote  |  Print  |  Notify Moderator

Got lost with the second solenoid. But still want to know about why the loss of voltage as was asked about earlier. Seems to be a separate "issue". (loose belt eg)

You could by-pass the second solenoid and be like we are if you wanted IMO.

Our 1991 E350 in sig has only the one relay, which charges the house batts whenever the engine is on, but is open when the engine is not on. (Don't know about when the ignition key is turned but not to engine on) No extra button in our rig to push that engages house to engine batts like you have.

So in our E350, if the engine battery were dead, I would have to run jumper cables from house to engine batts (a long way, but I have some that long).


1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
See Profile for House electronics set-up.
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas

maillemaker

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Posted: 01/17/20 07:17pm Link  |  Quote  |  Print  |  Notify Moderator

Quote:

But still want to know about why the loss of voltage as was asked about earlier.


Loss of charging was what precipitated my replacing the alternator. After replacing the alternator, I still had low voltage as indicated by a voltmeter plugged into the cigarette lighter (and a status indicator wired to the chassis batter).

When I whacked the house battery charging solenoid, and then got back in the vehicle, the volts were back up to 14.0 volts. So I assumed that the Charging Solenoid had something to do with the chassis charging circuit.

Now I see it does not.

So I don't know what caused the drop-out.

enblethen

Moses Lake, WA

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Posted: 01/17/20 07:52pm Link  |  Quote  |  Print  |  Notify Moderator

How much time between starting the rig and the voltage going up?
It could be the chassis battery had to come up a little before circuit board allowed relay to energize.
Try to locate the battery control circuit board and post number.
You may be OK!

BFL13

Victoria, BC

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Posted: 01/17/20 07:54pm Link  |  Quote  |  Print  |  Notify Moderator

So with no house charging from alternator, the engine battery showed low voltage as though no alternator, but new alternator same thing. You might have had a big house draw that should have been taken by the house batts that was taken by the engine batt, lowering the voltage.

I saw that with a loaded inverter clamped on my truck engine batt where the alternator could not keep the battery up and its voltage fell. (Not a MH situation, but still...)

First thing is to isolate the house from the engine entirely and make sure the alternator can run the engine batt and straight truck type loads ok.

Then see what is going wrong when you link in the house side.

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