Alternator Charging house batteries?

[Fla2RI]

After a long drive I checked the voltage at the "emergency start" solenoid and the engine side was over 13.7 volts and the house side was only 12.1 volts; shouldn't they equalize after a long drive? If my house batteries aren't getting charged while driving, where should I look for the problem? Where is the connection/regulator/switch between the two systems?

[H. Miller]

Most MH's keep the two systems totally seperate. The alternator charges only the chassis battery (s) and the generator, park electric or solar (if installed) charges the house battery (s). There are inexpensive add ons which will allow all batteries to be charged by any power source.
Hopefully someone will know more about your particular system.

[Fla2RI]

I've had several motorhomes and was always under the impression that the alternator would charge house batteries while driving, wow, guess I was wrong!

I'm thinking of replacing the momentary "emergency start" switch with a regular on/off switch (lighted) so I can flip it for an hour or so when driving, only when my house batteries are low.

[Luv2go]

Ford used to provide an aux battery charging circuit on their class C chassis that would connect the starting battery to the house battery with a solenoid while the engine is running.

The solenoid on our old coach ('93 E350 based class C) failed and I replaced it. It was located on the driver side firewall next to the fender and was pretty easy to spot because it looks like a starting solenoid and had 2 large wires connected to it, one on each side (note do not use a starter solenoid as a replacement it'll overheat and fail, use one rated for "continuous duty").

BTW, the real starting solenoid was located on the passenger side in front of the battery, you can confirm which solenoid it is by tracing the wires, the starting solenoid will have one wire going to the starter.

The momentary "emergency start" switch usually just closes this solenoid, so if it is bad wiring a switch won't help.

Maybe you have something similar?

Stewart

[Fla2RI]

I have a solenoid located under my entry steps (near coach batteries) which only closes when the momentary "emergency start" switch is depressed, this is the only way that I know of that connects the two 12 volt systems.

By putting an on/off switch instead of the momentary switch, I can direct the alternator to charge both systems when needed.

I always believed that the two systems were linked some other way, as salesmen have told me that the alternator would automatically charge the house batteries when driving??

Maybe I was thinking of travel trailer systems where a charge wire comes out of the hitch plug and charges the battery when driving?

[Clay L]

The alternator on most motor homes charges both the engine battery and the house batteries.
Shore power charges the house batteries and on some motor homes (many Fleetwood products) also charges the engine battery.
On Winnebago systems shore power does not charge the engine battery.

I don't know how your system is set up but Winnebago uses a continuous duty solenoid for the AUX (emergency start) solenoid. Besides being activated by the emergency start switch it is also activated by the run position of the ignition switch. This causes the alternator to charge both engine and house batteries.

There is also a battery disconnect solenoid (latching type) that disconnects the house batteries entirely. When it is in the disconnect position the house batteries are not charged at all.

[Fla2RI]

Thank you Clay, you've provided my answer. I'll have to check if the solenoid closes when the ignition is on. I knew that there must be a link between the two systems, I just didn't know that the ignition switch could close the solenoid! Thanks.

[Luv2go]

Clay posted before I did, so some of this info is duplicate.

Replacing the momentary switch sounds like the way to go. It would be really nice if Fleetwood would send you a wiring diagram, then you'd know if the solenoid was designed for "Emergency Start" or was there a "BIRD" or some other way to make it turn on to charge the coach batteries.

Does the key have to be on to make the solenoid close? If not you just have to remember to turn the switch off so the starting battery is not discharged while the engine is off.

I'd also check the wiring to the relay, if Fleetwood designed it for intermittent use they could have used smaller wire (and fuse size if fused) and a solenoid that is not appropriate for continuous use. I'd expect at least 8ga (good for about 60A continuous), maybe larger, for the wiring between the batteries. You can get the numbers off the solenoid and search for a data sheet to see if it is continuous duty.

FYI, during initial charging, my coach batteries would take over 60A from the alternator (as measured with a Link 1000 battery monitor). I ended up replacing my wiring with 2/0 (overkill) with a 150A fuse.

Stewart

[Fla2RI]

Well, the salemen were right. My motorhome does charge the coach batteries off the alternator. I did some more research and found I DO have an INTELLITEC ISOLATOR RELAY 00-00362-100, which is probably defective.
This relay is a black box with four wires, it monitors both systems and closes the solenoid when either system needs a charge, pretty smart! It also has a time delay so if your solenoid doesn't close right away, wait for at least 2.5 minutes. Intellitec has a nice brochure of it on their website which describes exactly how it is suppose to work. This is what I was asking about; this controller is the link that closes the solenoid to connect the two systems.

Now I must decide if I want to replace the controller or just go with the manual switch that I can control!!

Thanks for all your input!

[Old Bounder]

Originally Posted by Fla2RI

Now I must decide if I want to replace the controller or just go with the manual switch that I can control!!

Before condemning the controller, check to see that it is, or isn't picking the solenoid. It may, in fact, be the solenoid that is bad. Just because it "clicks" doesn't mean it's good.

Check the voltage on each side of the solenoid when you depress the momentary switch to make sure the contacts of the solenoid are closing. Then do the same when the engine is running.

My experience has been that the controllers are more reliable than the solenoids.

[hamguy]

Originally Posted by loulong

Before condemning the controller, check to see that it is, or isn't picking the solenoid. It may, in fact, be the solenoid that is bad. Just because it "clicks" doesn't mean it's good.

Check the voltage on each side of the solenoid when you depress the momentary switch to make sure the contacts of the solenoid are closing. Then do the same when the engine is running.

My experience has been that the controllers are more reliable than the solenoids.

For sure. I had a solenoid go 'south' but it clicked like a cricket. The VOM showed the cause. The replacement cost about $15.

[Latitude]

Newmar uses a 'BIRD' Bi-Directional relay similar to the Intellic Isolator and if it is working the House Batteries will charge from alternator when Engine running if/when the chassis Batts are full!!

AND

The Chassis Batteries will charge when on shore power or Gen When the House Batts are Full


Rick

[Luv2go]

I just looked at the 00-00362-100, it is a "BIRD". As loulong and hamguy said, check the solenoid before replacing the BIRD. My experience is that the solenoids go bad a lot. On our new coach, I went through 2 of these solenoids before I replaced it with a bigger one, and as I mentioned above the one on our old coach died also.

You can do a little troubleshooting on the BIRD if you have a DMM. When you run your engine, you should see your engine battery voltage from the "ignition" terminal to the "ground" terminal. After the delay, you should see the voltage at the "relay" input go from ~12V to close to 0 (referenced to the "ground" terminal). This means the BIRD is trying to turn on the solenoid.

If this is happening, then check the voltage across the solenoid (the big wires), it should be no more than 0.2V or so. If it is over that it is bad.

There is more troubleshooting info in this manual:

http://www.intellitec.com/PDF/5300362.100.pdf

IMHO, having a working BIRD and solenoid was well worth the time spent to troubleshoot it and replace the solenoid, I'd recommend fixing it over a manual switch any day.

Stewart

[georgetown350]

Usually while driving the engine batteries get charged first then the house batteries but when plugged into shore power the house batteries get charged first.

Steve