Chassis battery not charging using shore power

[Old Bounder]

Originally Posted by nothermark

Ummm, most DP's may charge the engine battery from the house circuit. Most motor homes do not. Very few class C's do it. I can't say for the low end A gas units. They outnumber the high end units by a comfortable margin. My only point is that "all MH's charge the engine battery from shore power" has a major problem.

FWIW The Magnum or whatever brand of Inverter/Converter is installed supplies power to the 12 VDC bus. Some monitor it and adjust the voltage better than others but they all share the trait of just supplying power to the bus. The House battery bank is also tied to that bus. The BIRD or BCC may also connect to that bus and supply power to the engine battery if it is designed to do that and is working properly. That is the general theory one has to start with when figuring out what any particular system is doing.

FWIW2 when on generator the system works the same way but the AC for the Inverter/converter comes from the Generator via the transfer switch or plug.

All very true, nothermark. My bad, I was considering only class-As, (both DP and gas) when making my comment. I will agree that most Class Cs are designed to a different price point and might generally lack some features in both the house and chassis areas, but there are certainly exceptions to every rule. There are Class-C rigs out there far more luxurious than my Bounder was ever meant to be.

[frede]

Originally Posted by Old Bounder

Your problem is most likely a defective Isolator/aux start/charge solenoid. This solenoid is located behind the circuit board in your BCC. It is a simple continuous duty solenoid, and is the shiny on in the middle of the two disconnect solenoids.

PM me an e-mail address and I'll give you the diagrams and test procedures.

Thanks for the test procedures, today was the first day it was warm enough to use them. Replaced fuse F17 so there is voltage on P4 #2. This also provided voltage on P4 #10 (12.62v) when I push the auxiliary start switch I can't hear it energize and voltage on P4 #10 rasies to 13.43. When I measure the voltage across the buss bars it reads 1.23v regardless of auxiliary start switch position.

I assume this is the Isolator/aux start/charge solenoid that need to be replaced: (I have a rev E board)

[Old Bounder]

Originally Posted by frede

Thanks for the test procedures, today was the first day it was warm enough to use them. Replaced fuse F17 so there is voltage on P4 #2. This also provided voltage on P4 #10 (12.62v) when I push the auxiliary start switch I can't hear it energize and voltage on P4 #10 rasies to 13.43. When I measure the voltage across the buss bars it reads 1.23v regardless of auxiliary start switch position.

I assume this is the Isolator/aux start/charge solenoid that need to be replaced: (I have a rev E board)

Correct. However, before you yank it out, maybe you could get someone to hold the aux start switch depressed while you measured the voltage on the yellow wire directly at the solenoid. If the voltage is getting that far, and it still fails, you can be assured that the solenoid is defective.

[frede]

Originally Posted by Old Bounder

Correct. However, before you yank it out, maybe you could get someone to hold the aux start switch depressed while you measured the voltage on the yellow wire directly at the solenoid. If the voltage is getting that far, and it still fails, you can be assured that the solenoid is defective.

The yellow wire on the solenoid has a standing voltage of 12.62v on it, when I push the auxiliary start switch the voltage increases to 13.43v same as what happen on P4 #10.

I think this should replace it nicely: Emerson 70-111224 12V 80 Amp DC Power Solenoid

[Old Bounder]

Originally Posted by frede

The yellow wire on the solenoid has a standing voltage of 12.62v on it, when I push the auxiliary start switch the voltage increases to 13.43v same as what happen on P4 #10.

Yes, that solenoid will be an adequate replacement.

It's a little strange that the solenoid has a standing 12.62vdc on it, even when the switch is not closed, unless you are plugged in to shore power, or the engine is running. The test procedures assume neither is active.

[frede]

Originally Posted by Old Bounder

Yes, that solenoid will be an adequate replacement.

It's a little strange that the solenoid has a standing 12.62vdc on it, even when the switch is not closed, unless you are plugged in to shore power, or the engine is running. The test procedures assume neither is active.

Opps, plugged in to shore power, should I start over?

[Old Bounder]

Originally Posted by frede

Opps, plugged in to shore power, should I start over?

Just unplug and set your meter to OHMS, and measure for continuity across the solenoid coil (yellow to black wires should only be a few ohms). I think you've nearly proven it to be bad.

[Old Bounder]

Just unplug, from shore power, and set your meter to OHMS, and measure for continuity across the solenoid coil (yellow to black wires should only be a few ohms).

[montyhp]

Originally Posted by Old Bounder

Yes, that solenoid will be an adequate replacement.

It's a little strange that the solenoid has a standing 12.62vdc on it, even when the switch is not closed, unless you are plugged in to shore power, or the engine is running. The test procedures assume neither is active.

No, that is normal. The 12.62 is the voltage of the battery bank and the 13 is the charging voltage. Sounds to me like the solenoid is operating as it is supposed to. When this happened to me it was a bad fuse in the bcc. It was #22 which is way down at the corner of the board.

[Randalpho]

When I replaced mine I went to my local O'Reilly Auto Parts and bought a Borg Warner S603 with silver contacts. It's rated at 80 amp continuous and 200 amp surge current.

The old solenoid would close when energized but the one contact lug was oxidized and would not pass current through. After replacing it, I cleaned up the old one and put it back together for a spare. I know I will never need it but just in case..........

[Old Bounder]

Originally Posted by montyhp

No, that is normal. The 12.62 is the voltage of the battery bank and the 13 is the charging voltage. Sounds to me like the solenoid is operating as it is supposed to. When this happened to me it was a bad fuse in the bcc. It was #22 which is way down at the corner of the board.

No, it's not normal at all. Frede's BCC circuit board (at release level E) does not have a fuse #22.

The board controlled solenoid pick voltage, (the 12.6), would Not appear on the small terminals (yellow wire) unless the BIRD function circuitry is signaling that charge voltage (13.2+) is available at the batteries. This suggested, correctly, that the coach was plugged in and the converter was running.

The "Boost" switch applies actual battery voltage, which would be 13.4+ with the converter running, directly to the solenoid.

Since all conditions seem to be present at the solenoid to close the contacts, I feel certain that it is defective.

[frede]

Originally Posted by Old Bounder

Just unplug, from shore power, and set your meter to OHMS, and measure for continuity across the solenoid coil (yellow to black wires should only be a few ohms).

I unplugged the power, still had 12.25v at the terminals. Ohm meter showed open, unless I reversed the leads. You're right I have no Fuse #22.

[twinboat]

If you have constant power to the small terminals, make sure the boost switch is not on.

[frede]

Originally Posted by twinboat

If you have constant power to the small terminals, make sure the boost switch is not on.

It's not, when the boost switch is on the voltage increases to 13.43v and someone has to hold it on.