Battery not charging

[TallPaul]

Okay, bought this motorhome used last May and took one trip. Never used it in a situation where the furnace was run to drain the battery, so didn't notice any problem, but now I see that the house battery does not charge when teh engine of the motorhome is running. It charges plugged in to shore power or with the generator though.

I tested neg bat terminal to either side of both the breaker and a fuse that are in the battery box and always same voltage 11.98, whereas engine battery is charging at 14.8 volts.

I recall there is a heavy red cable under the hood and next to the battery that is not hooked to anything. It is as thick as the main battery cables. So I wonder if this cable should be attached to the battery and then my house battery would be charging. Is that how it works?

So did the cable get left off when prev owner bought a battery or was it taken off because there was a short?

It will be interesting. Sat I will have to take my jumpers and see if that cable under hood connects, though I recall testing it and there was no voltage off of it, but then shouldn't be as there should be one way electrical gate, right, so that the engine does not drain off the house battery? I do not have the switch to start the engine off the house battery.

Thanks.

[TallPaul]

Okay, bought this motorhome used last May and took one trip. Never used it in a situation where the furnace was run to drain the battery, so didn't notice any problem, but now I see that the house battery does not charge when teh engine of the motorhome is running. It charges plugged in to shore power or with the generator though.

I tested neg bat terminal to either side of both the breaker and a fuse that are in the battery box and always same voltage 11.98, whereas engine battery is charging at 14.8 volts.

I recall there is a heavy red cable under the hood and next to the battery that is not hooked to anything. It is as thick as the main battery cables. So I wonder if this cable should be attached to the battery and then my house battery would be charging. Is that how it works?

So did the cable get left off when prev owner bought a battery or was it taken off because there was a short?

It will be interesting. Sat I will have to take my jumpers and see if that cable under hood connects, though I recall testing it and there was no voltage off of it, but then shouldn't be as there should be one way electrical gate, right, so that the engine does not drain off the house battery? I do not have the switch to start the engine off the house battery.

Thanks.

[GaryKD]

Hi Paul,
I've asked a moderator to link your post to the Gulfstrream owners forum. The bottom line is it all depends on how Gulfstream built your coach.

[GStream40]

TallPaul,

What is the model of your coach and chassis?

Ron

[TallPaul]

Ron, It's a 2000 Conquest Sport 28 foot on a Chevy van chassis.

Odd thing is there is only one house battery and there is no switch to cut out the battery. I pull the fuses on the LP detector and fridge as they can drain the battery, but even with those fuses pushed back in the battery did not charge.

[TallPaul]

Update: Called Gulfstream and they said to check the solenoid and the isolator relay. Both are supposed to be on the inner fender like a circuit panel or something.

The solenoid turns off the engine alternator from charging whenever you plug into 110 or run the generator.

I am not sure how the isloator relay works.

Then I called my dealer, which is a Gulfstream dealer, and their service manager said the solenoid is the likely culprit.

Assuming I can find it, I will start the engine and test for voltage on either side of the solenoid. If putting out charging voltage on one side, but only the battery voltage on the other, then I will have isolated the problem.

BTW, what voltage should I expect the engine alternator to be putting into the charging of the house battery, same as it puts to the engine battery?

Shore line charges house at 13.8 volts.

Alternator charges engine battery at 14.8 volts.

[RV Wizard]

It should be very close if not the same voltage as the chassis battery(s). Look for any loose or corroded connections as you troubleshoot. Let us know what you find.

[TallPaul]

Ah, the terminology is house battery vs chassis battery. Good to know. Will report back on what I find. Plan to look at tomorrow.

UPDATE:

Okay, house battery was 11.98 volts Wed, so I plugged in to shore power. 24 hours of shore power charging it at 13.8 volts, then I unplugged it.

After half an hour unplugged, the battery read 12.78 volts.

After 21 hours unplugged (and it hit about 17F over night), the battey reads 12.62 volts.

So I conclude the house battery is in pretty good shape.

[TallPaul]

36 hours after the 12.62 reading, the battery reads 12.57. Seems okay.

I found the heavy red cable (that is not hooked up under the hood but lies next to the chassis battery) goes under the motorhome to a thing that looks like a relay. The thing is cylindrical about 2 inches by 2.5 inches at most. The unhookedup cable is on one terminal and two heavy red cables from the house battery are hooked to the other side of it. There is one more terminal that has a small wire and I am not sure where this wire goes, but maybe into the cab.

So what is this thing? Could it be the battery isloator relay? Would the battery charge through a full sized cable like that (same approx size as cables on chassis battery for starter).

Or is this thing a solenoid that can switch to start the engine off the house battey when the chassis battery is low (although I don't have such a switch)?

[TallPaul]

I believe the problem is solved.

I hooked the red cable to the chassis battery. With that cable hooked up, I get the two separate voltage readings, one at house battery, the other at chassis battery, so results for the four conditions are:

1) Shore power off, engine off: no connection between batteries. Separate and different voltage readings, per each battery.

2) Shore power on, engine off: Charges house battery, but not chassis battery.

3) Shore power off, engine on: Charges both chassis and house battery.

4) Shore power on, engine on: Both chassis and house battery charging at engine alternator voltage output.

Bottom Line: Land line charges house battery only and only when engine is not running. Engine alternator charges both batterys when running.

So, is the relay/isloator/whatever defective? That is, should it not charge house battery when shore power is on? Will this cause a problem? However, I am not likely to ever run this condition as I will stow shoreline before driving (and starting) engine. Only time it might happen is if I am working on it (oil change for example) and start it for a few minutes and happen to have it plugged in.

However, with the engine on, all lights and other 12v appliances are operating around 14.5 volts. If this setup is not correct, but just happens to work, it could shorten the life of bulbs, etc., but probaby not a big deal.

Lastly, I assume if I substitute the generator for the shore power in above four tests, I will get same results.

So, am I good to go or do I need a new relay/isloator/whatever thing?

It may be that the factory could have added the start-engine-off-house-battery switch for merely the price of the switch as I bet this setup is everything but the switch.

Thanks for all the help.

If my "solution" is correct, then the tech at Gulfstream didn't know what she was talking about. What makes me think my solution is correct is that there is no small wire between the house battery and the engine alternator, which one would expect from the Gulfstream folks's advice.

[RV Wizard]

The solenoid is for connecting both chassis and house batteries together in the event one side is weak to get that side engine (chassis or generator) started. You should have a switch on the sash marked "Boost" or "Emergeny start"; somehting like that. The chassis batteries are not going to be charged from shore power unless you install something like a charge wizard.

[TallPaul]

I do not have a "boost" or "emergency start" switch. My Class A Itasca had that switch on the dashboard, but this Gulfstream does not. At any rate, it is charging the house battery when the engine is running and that is the main thing I wanted to correct. I never thought the chassis battery was supposed to charge off shore power and it should not normally need to. The boost or emergency start is a nice feature, but if one maintains their batteries properly, should never be needed. Also I have jumper cables long enough to reach between the two batteries if I ever get in a pinch.

At any rate, it sounds like it is perfectly safe to run it like this.

In case I decide to go that way, the Charge Wizzard (or like device) would go in the same line in place of the solenoit?

Thanks.

[RV Wizard]

Here is a little info on the charge wizard
http://www.progressivedyn.com/prod_d...ge_wizard.html. You would not have to remove any existing components to install the charge wizard.

[TallPaul]

Thanks. Nice product. Presumably you would leave the motorhome plugged in all the time with Charge Wizzard.

Looks like the Charge Wizzard simply plugs into the converter so it would not regulate charge from the chassis battery via the cables I now have.

The chassis will be charging the battery around 14.5 volts, which I gather is a bit too high.