Alternator on Holiday Rambler Imperial

[CoachDave]

Hi Gang!

I have a 1987 Holiday Rambler Imperial, 40 foot diesel pusher. Last November I had an issue with starting, i.e., turn the key and nothing. It would eventually start but continued to get worse. It was diagnosed as a bad starter so the starter was replaced and worked fine for awhile. In March came out of a restaurant about 10:30PM, and would not start. AAA et al folks came and got it started. Next day, no start, again. And again some kind folks to the rescue and started so went to the shop of the folks who came to our rescue at the restaurant. Cleaned the battery cables and solenoids, thought it needed new ones, but could not get any. Everything fine (again). Unfortunately he cleaned the coach batteries and not the chassis. Got stuck at a rest stop and once again a trucker came to our rescue. Got to the campground and went to another establishment. After spending the day there, NEW batteries et al we were about to start up again, and you guessed it. So we spent the night and another starter was installed. I am now into this for about $2200. Got back to MA and was going to have my mechanic check it all out, but could not get it started because the brand new chassis batteries were dead. Mechanic got it started, brought it to his garage and diagnosed the problem as a bad alternator. Of course one could not be found to fit our classic, vintage bus and he put the old one back in as he was going to have to rebuild it and we had to leave on a trip. There was a battery charger in the battery compartment left from the previous owner (I think now I know why). Between the highway driving and the battery charger we have been OK for about two weeks, but have about two weeks to go on our trip before retuning to MA to have the alternator rebuilt (I think). I know this is rather lengthy, but has anyone else had a similar problem, and do you think it is indeed the alternator or something else that should be checked first?

Thanks,

"Coach Dave"

[Guest BillAdams]

When you check the batteries with the engine off you should see something close to 12V. When you start the engine the alternator should kick in and you should see something closer to 14V if the alternator is working and little or no change in the battery voltage if the alternator is not working properly.

[wolfe10]

If Bill's test shows the alternator bad (i.e. with engine running, large wire at alternator below 13.2 VDC) determine the brand of alternator.

Call that manufacturer and ask for their recommendation for an authorized alternator rebuild shop in your area. Take the alternator to them.

BTW, I do this as preventive maintenance every 100,000 miles. MUCH, MUCH cheaper to have a good shop put in new bearings and brushes before it fails than to buy a new alternator when the bearings seize up and destroy the alternator. I just had this done on my Hehr Powerline alternator-- cost less than 10% of the cost of a new alternator. AND much less chance of a breakdown on the road.

[garykd]

For those reading this thread, check to see if your generator charges the chassis batteries when it is running. If so and you find yourself in a similar situation (alternator not charging) one can run the generator while driving down the road. The chassis batteries will be charged up by the generator and ready for their next use. This is a temporary fix, until the alternator problem can be solved.

[wolfe10]

For those reading this thread, check to see if your generator charges the chassis batteries when it is running. If so and you find yourself in a similar situation (alternator not charging) one can run the generator while driving down the road. The chassis batteries will be charged up by the generator and ready for their next use. This is a temporary fix, until the alternator problem can be solved.

Gary is correct for SOME coaches. But, on over 50% of coaches on the road, the converter, charger or inverter/charger ONLY charges the house batteries, not the chassis batteries. For those where the chassis batteries are not charged, in many cases, the battery BOOST SWITCH can be used. So, the converter, charger or inverter/charger charges the house batteries. The boost switch "combines" the house and chassis batteries so all are charged.

Brett

[Koliver]

Brett

On my 98 Contessa, the battery boost switch is a momentary switch. I suspect that is the general case on most coaches, and only rarely will there be a combine switch that can be left on. On this or some other forum I have seen advice that the other components in the boost circuit will suffer if the boost is held on more than momentarily, to get started.

Dave:

Also on my coach, the chassis batteries get charged directly from the alternator, and are supposed to get charged by an "echo charger" while plugged in to shore power. The Echo can fail, allowing depletion of the chassis batteries while parked, as the loads don't all end when you turn off the key. I have diagnosed this problem, by measuring voltage at the chassis batteries, while plugged in to shore power, and finding steadily dropping voltage, while the house batteries were happily guzzling the 13.8v being supplied by the charger. This likely why you have found a small, dedicated charger in the bay, as a replacement for a dead echo charger.

Sounds like you have had more than one piece of deferred maintenance catching you, but are close to the end. Your report suggests you now have:

1. clean terminals all around;

2. new chassis batteries;

3. a charger for just the chassis batteries, so you know when they are getting shore power;

4. knowledge of where the alternator output is, so you can measure it;

5. no failures on the house batteries, so you know the charging system works, both by the alternator and through the charger

when on shore power.

A minimal amount of further testing with a good AVO should sort it out.

Check that small, separate charger too. It may have too little output to do any more than supplement, as your continuing loads to keep up the clock in the dash, the ECM for both Engine and Trans, etc., may be significant. You can check those loads too, if you have the right test equipment, but just reading the output numbers on the little charger will tell you its highest possible output. See if you get a healthy spark from it when you connect it to the batteries, after plugging into shore power. If you don't, its output may be low.

If that is the case, look at replacing it with something of greater capacity. Xantrex has an Echo charger, or there are plenty of small "smart" chargers in NAPA or similar stores that will do a fine job.

[CoachDave]

Hi Gang!

Thanks for the replies and advice. Not sure I understand some of it, but thanks anyway. r.e., the battery charger, when stopped at CG, I plug the battery charger into shore power so, I assume, that it is constantly keeping the batteries charged. My mechanic said, truthfully I hope, that as I drive down the road the batteries are charging. It does read at a constant 14 number on the gauge.

Thanks again.

Dave

[CoachDave]

Hey Koliver!

You forgot to mention my two new starters!!!!

Thanks again.

D

[wolfe10]

Brett

On my 98 Contessa, the battery boost switch is a momentary switch. I suspect that is the general case on most coaches, and only rarely will there be a combine switch that can be left on. On this or some other forum I have seen advice that the other components in the boost circuit will suffer if the boost is held on more than momentarily, to get started.

You are correct, yet two different ways that coaches can be wired. Our boost/combine switch is on/off, not momentary. Is controls a constant duty relay. And no, except in an emergency you would not want to run an intermittent duty solenoid for long periods of time.

The proper emergency "work around" for "driving with an alternator not charging, but generator on and powering the converter, charger or inverter charger which charges the house battery but not the chassis battery" would be to label the wire(s) on one of the large lugs of the boost/combine solenoid. Move them/add them to the other large lug. All you have done electrically is that the system will think the solenoid is passing power from one large lug to the other (i.e. the combine switch is on, but without having to have the solenoid on). Make sure to put them back on the other large lug when you stop or all batteries will stay connected and will discharge if dry camping.

Brett