Alternator Not Charging House Batteries While Driving

[D_E_Bishop]

See the third reply.

Last December I was trying to find the location of the BIRD in my Adventurer, dougrainer helped me out with an explanation of battery charging in a Winnebago. Instead of a BIRD, my Winnie has a push to close or momentary single pole, double throw, Battery Boost switch that actuates a solenoid that has a feed from the chassis battery on one pole and a feed from the house batteries on the other. This connects the batteries together during starting if the chassis battery is low. When you release the switch, the normally closed contacts close and the Ignition Accessory circuit feeds the solenoid and automatically closes the contacts after the engine starts and both banks charged by the chassis alternator.

That solenoid would work if I pushed the Boost Sw. but not when on the ignition. The switch or solenoid had a loose connection or whatever and when I checked and tightened all the connections and actuated the solenoid using a jumper wire, it seemed to be working fine, I started the engine and the charge rate was the same for both batteries, so I figured I had it fixed.

Recently we took a three week trip up the coast and all but one of the campgrounds we stayed at had full hookups so when I checked the batteries and both always appeared to have a full charge. Then we spent a couple of days at dry campground and when I checked the batteries, the chassis was fully charged and the house low.

Well I finally got around to checking everything out a week ago and everything appeared to be fine, I flipped the battery disconnect and heard the solenoid actuate and the lights and steps and all appeared to be working normally. I started the engine to move the rig out of its space and that was all normal but when I walked back to the bedroom, I pasted the panel with all the displays for the tanks and generator and pushed the battery voltage switch to the Engine side and it read 14.4 volts but the House side read 12.8.

The long and the short of it is, right now I have no power through the battery mode solenoid when the engine is running but if I manually actuate the solenoid I do have 14.4+/- on both batteries. As I tell folks with electrical problems, start at the beginning and check everything in order, that way you don’t miss anything. Well I don’t know physically where the beginning is in this circuit. I know there are two 12 volt inputs somewhere in the front end. One is a steady 12 volts and may or may not be fused and is connected to the NO contact of the Boost switch and the other is Ignition/Accessory side of the ignition switch and it may or may not be fused and is connected to the NC contact, the armature wire goes to the solenoid. I know where every connector is for the wire connected to the armature and the solenoid. The schematics I downloaded from Winnebago, do not show or state exactly where or to what point in the Ign. Acc. circuit the wire to the boost switch is connected, in fact in the wiring manual it doesn’t even mention the boost switch transferring from chassis wiring to house wiring. It does for a lot of other accessories but not the boost switch.

Today I’m going to try my trusty little Sperry Wire Tracker, if I can get the boost switch out of the dash or the connector off the back of the switch. I’ll first check that there is power on the Ign. Acc. Switch side, if there is I’ll know it is the switch, if no power, I’ll try and trace the wire to its termination.

So If anyone has any ideas other than tearing the entire wiring system apart or just installing a jumper, I’d appreciate a response.

Just a follow up after three hours of trying to solve this problem. Both batteries are now charging from the alternator and the battery disconnect switch that wouldn't work yesterday are working. I have no idea what exactly had an affect on the charge circuit but I have an idea about the disconnect, that is probably residual magnetism.

I did open every connector from the battery compartment to the front engine cover(cap) and found one blown fuse but it was on a always on circuit. I also removed and reinstalled every one of the relays I could find under the dash and in front of the firewall. I tried to trace the wire from the switch to the Battery Accessory connection but to no avail. To many wire loom and dark place where my hand won't go.

But for now it is working correctly. I'm still looking for the point where the wire from the battery accessory point is located. If you have an idea, please post it.

TIA

[D_E_Bishop]

My Winnie does not have a BCC or BIRD. Some may have but mine doesn't and my understanding is they just don't use them.

For what ever reason, my battery charging system is now working be it from an act of god or with me breaking and making every plug, relay and fuse involved and that cleansed the contacts, I don't know. I now, however, know the physical test points are and if the problem reoccurs, I can get my trust test light or my Fluke DMM and do a circuit chase.

If I have to install a jumper, I know exactly where I will install a "T" splice and jumper to provide the IGN RUN power until I positivly identify the open. If any of you are truly interested in looking at the schematics, PM me and I will shoot you a copy of the pages that are on Winnies web site.

[scrubjaysnest]

Although our set up is different then yours, we had a similar problem. The B.I.R.D was wired to the wrong side of the relay that isolates cranking from house batteries. In our case neither the converter or the solar would charge the cranking battery because the B.I.R.D never saw a high enough voltage to start timing.

[ksg5000]

I had similar problem with my Fleetwood - I got frustrated and just installed a wire running from my radio fuse (only operates with ignition switch on) to the solenoid. Any auto parts house will show you how to put a second wire/jumper on that fuse. In my rig the fuse was located inside the rig and I ran the wire through one of the grommets on the fire wall to the engine compartment where my solenoid was located. Might have been other solutions but this one worked and has been working for the past 7 years. Just a thought.

[enblethen]

Did you find make and model of the BCC?
On my rig, the chassis battery via the electronics must be charged to a given level before the charge relay will be energized,

[D_E_Bishop]

I found the "Run Only Power" circuit. There is a circuit from the chassis that is only hot when the ignition key is in the "RUN" position. In the "Start" position certain accessories are disconnected from the battery circuit and reconnected when the engine starts and the key is returned to the run position. The Battery Mode Solenoid, is one of those accessories.

When the engine starts and the key returns to the Run position, the solenoid is reactivated and the coach and chassis batteries are coupled and both charge off the engine alternator.

Now if this happens again I can trace both circuits and find the failure in the circuit.

Thanks for the answers Guys.

[enblethen]

Look in your battery control center for a blown fuse.
See if you can find and post make and model of battery control center.
One of my print outs says it is fuse 20 in this particular model of battery control center.

[DrewE]

When it's not working, check the voltage of the wire to the NC connection of the boost switch (from a run/accessory circuit in the chassis). If there's proper voltage there, then the problem pretty much has to be the switch itself. If there isn't power on that wire, then trace it back and see where it disappears. If it's too hard to trace, you could run another wire from some other reasonable location...and make a note of it in your literature for next time.