2018 Spirit chassis alternator not charging house batteries

HittheRoad · 05-26-2020, 02:55 PM

The manual says that the chassis alternator should charge the house batteries but it does not. The solenoid next to the batteries engages when I press the battery boost button. First is the chassis suppose to be charging the house batteries when the motor is running and if so is there a different solenoid that is for charging than for boosting?

Morich · 05-26-2020, 04:26 PM

Let's make sure we are both talking the same first? I think of the battery switch on the dash as being a temp method to connect the two strings together, like in the case of a rundown start battery, we can push the switch to let us connect both strings to get going.
But that is a pretty temp thing and will not leave them connected after we release the button. Is this the switch you are finding works the solenoid but then doesn't charge the coach battery? I "think" there is another solenoid which should pull up each time the engine starts but that does need some checking before saying for sure.
It's helpful to have about all the specific info like year make model and size as each unit does have it's own set of drawings it cuts down on the guessing if we can go more directly. Some of the years even have to use the serial number due to changes in the middle of the year!

rk911 · 05-26-2020, 04:54 PM

yes, in all of the Winnebago motor homes we have owned since 1986 the engine when running will charge both the chassis and house batteries. why do you believe that the house batteries are not being charged?

HittheRoad · 05-26-2020, 04:55 PM

here is the link to the page for my rig: https://www.winnebagoind.com/diagram..._325b_wire.htm

HittheRoad · 05-26-2020, 05:00 PM

2018 spirit 25b

HittheRoad · 05-26-2020, 05:04 PM

when I press the battery boost it does click the solenoid right next to the house batteries under the steps, can it not be that one is used for both boost and the chassis charging?

HittheRoad · 05-26-2020, 05:07 PM

If325b 70322x2

Phil G. · 05-27-2020, 09:48 AM

Our 2005 (Itasca) Spirit Class C, with the Ford V10 and it's 130 amp alternator, charges both the chassis battery and the two coach batteries.

However, over the years I've had two of the solenoids fail that connect the alternator to the coach batteries - I'm on my 3rd solenoid now. With both solenoid failures, the solenoid still clicked when I turned the ignition key ... but with the engine idling, there was no alternator voltage appearing on the terminals of the coach batteries.

I believe the cause was some kind of failure of the contacts of the solenoids - perhaps corrosion/erosion of the contact surfaces.

I now have both a digital voltmeter and a digital ammeter mounted right on the dash in the cab. The voltmeter shows the voltage on the coach batteries' terminals, and the ammeter shows the current flowing either into (a positive reading) or the current flowing out of (a negative reading) ... the coach batteries.

The solenoid I have in there now is a heavy duty industrial rated one with silver plated contacts. Just as a note, after a few days camping without hookups the stock Ford 130 amp alternator has provided as much as 70 amps charging current going into the coach batteries while the engine was only idling.

HittheRoad · 05-27-2020, 11:56 AM

Spoke to Winnebago - seems that the solenoid should power on all 3 posts when motor is running and it does not - not on the middle post

Morich · 05-27-2020, 01:13 PM

OK! Looks like time to do a little testing on the solenoid. I been out spending three hours talking to get our DISH receiver setup again. If we don't use it they get it in a mess with it not getting updates! DUH! It doesn't get updates when it's in storage?
So that makes looking at a solenoid lots more fun!!

We may be getting a bit of bad or confused info on the test, so let me tell you what I would do. To connect the two battery strings together there will be a big heavy post with heavy battery cables on one side going to the start battery and then the same on the other side going to the coach battery with smaller lugs and wires that are the control battery that make the big "slave" do the work. So to keep it simple, if I can trace out the battery cable that comes from the strat battery, leave it connected but take the other side with the cable going to the coach batteries off, then I can see there is no battery voltage on that empty lug, but battery from the start side shows up there when I start the engine!
The solenoid is just a big switch that moves when battery flows through the control wiring. So I first want to see if the thing is passing battery voltage from one side to the other. If it does that, I don't have to get into thinking much about any of the controls or if the solenoid is good as it is doing all it needs to do! Maybe something as simple as the ground cable on the coach battery is dirty?? Pays to look first if it is handy but that's just a different part.
But if it doesn't pass that voltage, when somebody starts the engine, I've got to look at the control wiring or assume the solenoid is bad. If it clicks but doesn't pass the voltage from one side to the other, I call the solenoid bad. No click, I have to look at the control wiring.
Lots of different ways to work but that would be my plan.

Morich · 05-27-2020, 01:23 PM

I don't know if you have found this drawing yet but it might make sorting the cables a bit easier as page one gives the color of the tape which marks which cable ifs which:
https://www.winnebagoind.com/diagram/2018/000043326.pdf
Page two is a mess but page three may be easier to see where to expect the cables?
You know about being really careful about not shorting out the battery posts!! Flash of fire and a big burned spot on the tools! I pad things down with rags before starting too much.