Coach batteries not charging from alternator

[mglasgow]

I am new to this forum, so I ask for your forgiveness ahead of time if I inadvertently violate any forum etiquette.

I have a 2002 Winnebago Minnie Winnie Class C on a Ford E450 Chassis. On a recent trip home, my coach batteries stopped taking a charge from the alternator (which I unfortunately found out when I tried to start the generator one evening in a WalMart parking lot after driving all day). Needless to say it was a very 'rough' night.

Once I got home I started to try and diagnose the problem. The coach batteries will charge if plugged into shore power, and it will also charge off the generator. Admittedly, I am not an electrical genious, but being somewhat mechanically inclined, I did check the 'easy' stuff, such as fuses, breakers, etc., but everything appeared to be okay. So, I did what any electrically challenged person would do, and called the local Winnebago dealer to make an appointment. After being laughed at and told that they were booked through the end of July, I decided to continue to troubleshoot on my own.

I found an earlier post on this forum that had a somewhat similar issue with the Trombetta battery solenoid. So, I figured what the heck, and I ordered the part off the internet, replaced it, and still have the same issue. My neighbor saw me kicking and yelling at the motorhome and suggested I take it to the local Ford dealer to see if they might be able to track down the issue, which I did. They had it for 4 days (granted one of the days was Sunday), and called me today saying they definitely eliminated the Ford Chassis items, such the alternator, fuses, etc., and that I would need to take it to an RV shop for further diagnosis. The shop foreman seemed to recall a similar issue a while back that involved the Auxilliary Battery Switch on the dash causing this issue, but he wasn't sure and didn't feel comfortable saying this was the problem.

So, this is my story and I am looking for some advice on where this electrical gremlin might be hiding out withing my motorhome. Any advice would be greatly appreciated.

[Petro]

Mglasgow;

First let me be the first to welcome you to iRV2 and the Winnebago Forum. I am not familiar with your coach wiring but I had the same problem with mine and replacing the charge solenoid solved my problem. You should be able to check voltages on each side with the coach running and see if the voltage is passing through.

Don

[mglasgow]

Petro,

Thanks for the warm welcome. Can you instruct me regarding how to test each side?

[Petro]

Originally Posted by mglasgow

Petro,

Thanks for the warm welcome. Can you instruct me regarding how to test each side?

My charge solenoid doubles as the emergency start circuit. Pushing a switch on the dash activates the solenoid tyeing the coach and chassis batteries. I understand you have already replaced your switch. When your coach is running your chassis side of the switch should show a little over 14 volts on a volt meter. If the switch is not passing through the power your coach side will only show the static charge of about 12 volts or a little over. Your power cord should not be plugged in during this test to stop the charging by your charger or converter. If you have a difference in voltage between the 2 sides the current is not passing through. If the voltage is about the same on the 2 sides the switch is passing the power through. On my Chieftain the switch is activated by power from the ignition switch when the engine is running. If you have a solenoid like mine you should be able to check for voltage at the terminal that activates the switch. If you have no voltage there when the engine is running you could have a blown fuse if it has one or a bad wire.

I hope I have helped you. Hopefully someone else will jump in here with a coach like yours with more specific info.

Don

[mglasgow]

Petro,

There is a little over 14 volts on the chassis side of the solenoid, and 12 volts on the coach side of the solenoid. Would this lead you to believe that the brand new solenoid I just installed is bad? Also, does the condition of the coach batteries have any influence on the solenoid working the way it should? I thought I had read somewhere that if the coach batteries are in bad shape, that the solenoid will prevent the alternator from charging them so that it won't 'burn itself out'?

[Petro]

Originally Posted by mglasgow

Petro,

There is a little over 14 volts on the chassis side of the solenoid, and 12 volts on the coach side of the solenoid. Would this lead you to believe that the brand new solenoid I just installed is bad? Also, does the condition of the coach batteries have any influence on the solenoid working the way it should? I thought I had read somewhere that if the coach batteries are in bad shape, that the solenoid will prevent the alternator from charging them so that it won't 'burn itself out'?

Does your solenoid look like starter solenoid on older cars? Does it have a small post with a wire connected to it that activates the solenoid? Do you have a emergency start switch in the cab?

I ask these questions because my experience with Winnebago is limited to a 97 Adventure and my present Chieftain. I have had to change the solenoids on both motor homes for the same reason you describe.

The fact that you have 14 volts on one side and 12 volts on the other side points to the fact that no power is passing through it. If you have a small post in the center with a wire attached to it check for a voltage reading there while the engine is running. If you have power to the solenoid which is supposed to activate the solenoid than I would suspect a bad solenoid. Was the replacement solenoid an exact replacement as you had? The specs specify a solenoid rated for continuous duty and not one that is only rated for intermittent duty. A wrong solenoid would burn out because it is activated when ever the engine is running.

I have never heard of a charge solenoid not activating because the coach batteries were bad. That solenoid I believe is activated by the engine running. Perhaps somebody will jump in here and correct me if I am misinformed.

One last question for you. Would you like to be a member of the Winnebago Owners Club? It doesn't cost anything and basically identifies you as a Winnebago owner. I can help you with that if you wish.

Don

[mglasgow]

Petro,

The solenoid was an exact replacement which I ordered directly from Lichtsinn Motors (one of this forum's sponsor's). It is a 3 post model, with 1 large post on each side, and a smaller post on the front, and yes, I also have an emergency start switch on the dash.

[Petro]

Mglasgow;

With the ignition switch on have someone activate the emergency start switch. You should be able to feel and hear the solenoid activate. If it does not check for voltage on the little post. There should be be 12 to 14 volts on that little post when activating the emergency start switch and also when the engine is running. If you have voltage at that post I suspect a defective solenoid. If no voltage I would check for a reason for that. A phone call to Winnebago Customer service should help you to know if that circuit is fused or what to look for. Their telephone number is 800-537-1885. They have always been very helpful to me when I have called them.

Good Luck and let us know how this works out for you.

Don

[mglasgow]

Petro,

There is no voltage at the small post at any time, engine running or not, emergency start switch engaged or not.

[Petro]

Originally Posted by mglasgow

Petro,

There is no voltage at the small post at any time, engine running or not, emergency start switch engaged or not.

You have done an excellent job of diagnosing your charge problem. I believe you have determined it is not a bad solenoid. I would look for a bad fuse in your panel. I believe you are at telephone call time if you don't find a bad fuse. A call to Winnebago should help point you in the right direction.

Good luck;
Don

[hamguy]

To see a schematic of your system, see -

http://www.winnebagoind.com/diagram/...ire_137670.pdf