How to make sure the alternator charges house batteries

mlafleur · 08-03-2021, 09:57 AM

Hello fellow RVers,
(2004 Georgetown 308 XL)

This morning I swapped my house batteries (3 years old) that wouldn't hold a charge anymore for two spanking new golf cart batteries from Costco.

I have a distinct feeling that the alternator does not charge the house batteries. 2 years back I disabled the engine auto-boost feature because even when not engaged, the house batteries were still connected to the engine battery, which caused all the array to drain, leaving my engine stranded. Could it be the case that by doing so, I prevent the alternator from charging the house batteries.

Is there a way to verify my theory? How do I check if the alternator charges the house batteries when driving about?

Thanks a lot,

Maurice

DougW · 08-03-2021, 10:41 AM

It is very possible you disconnected the charge wire. It is an easy test. With the RV not connected to shore power, put a DC voltmeter on the house battery with the engine off and read the voltage, start the engine and read the voltage of the house battery again. It will be higher with the engine running if the engine is charging it.

kcmusa · 08-03-2021, 11:15 AM

Use a volt meter. If charging the voltage should be above 13 volts.
The 12volt Side of Life (Part 1)

bubbles · 08-03-2021, 11:23 AM

The auto boost (aux start) and cross charging circuits are independent but both do energize the same relay. They are parallel interconnects. The previous post check will verify. Don't quite understand your boost switch and batteries issue. Your coach is a 2004 but think this area would be the same as later vintages.

mlafleur · 08-03-2021, 12:37 PM

Thanks for the suggestion, I'll run the test later this week. I might also invest in a new solenoid and reconnect the auto boost feature. BTW, if the house batteries are dead, can I use the auto boost to jump start the generator?

bubbles · 08-03-2021, 01:28 PM

As long as there is enough power to energize the interconnect solenoid then I would think yes. Of course you could always start the engine and allow the cross charging to charge the coach batteries enough to a level that will start the genny (start it with engine running).

mlafleur · 08-06-2021, 01:37 PM

Hello,
So I ran tests and herés what I have:
When the engine is not running, I have 12.7V on the house batteries.
With engine running, same thing.
It means the selenoïd does close the circuit.
Ran to the parts store, the owner suggested I check the voltage at the actuator connectors, with the engine running I should have 12V, forcing the selenoïd to close the circuit and allowing the alternator to charge the house batts. So the selenoïd might still be good, but the ignition does send the 12V signal for it to close.
What’s next?
M

bubbles · 08-06-2021, 01:44 PM

Not familiar with a 2004 GT. What kind of a battery control center (B.I.R.D/SDC-?) do you have?

mlafleur · 08-06-2021, 03:03 PM

I have the Intellitec BD0

eric1514 · 08-06-2021, 03:20 PM

If your boost switch was not disconnecting there’s a good change the isolation solenoid is shot. Put a new one in. It’s that silver canister in your photo.

Buy a continuous duty one. They’re expensive if you run down to your local auto parts store. $80+. If you can wait a day or two, they’re about $35 online.

bubbles · 08-06-2021, 05:13 PM

here's the info.
https://intellitec.com/wp-content/up...-Isolators.pdf

mlafleur · 08-07-2021, 11:26 AM

OK, thanks. I found the following on-line. Must be the proper part. At $120CAN, it better be!

https://www.amazon.ca/-/en/Intellite...8353801&sr=8-1

bubbles · 08-07-2021, 01:36 PM

Quote:

Originally Posted by eric1514

If your boost switch was not disconnecting there’s a good change the isolation solenoid is shot. Put a new one in. It’s that silver canister in your photo.

Buy a continuous duty one. They’re expensive if you run down to your local auto parts store. $80+. If you can wait a day or two, they’re about $35 online.

But if it is the relay that would mean it was always in the energized state and therefore he should have read the alternator output on the coach battery.

DougW · 08-07-2021, 02:16 PM

Quote:

Originally Posted by bubbles

But if it is the relay that would mean it was always in the energized state and therefore he should have read the alternator output on the coach battery.

That would be true except that in his first post he mentioned disabling the boost feature which probably means the old relay is no longer in the circuit and the battery cables are disconnected.

bubbles · 08-07-2021, 06:54 PM

Quote:

Originally Posted by DougW

That would be true except that in his first post he mentioned disabling the boost feature which probably means the old relay is no longer in the circuit and the battery cables are disconnected.

The picture in post #9 looks like all the battery cables are connected. I think he disabled the boost switch itself. I hope somehow the relay is the issue after he spends that much money. It's like changing parts till it's fixed, no matter how much it costs. Oh well.

eric1514 · 08-07-2021, 07:29 PM

Quote:

Originally Posted by bubbles

But if it is the relay that would mean it was always in the energized state and therefore he should have read the alternator output on the coach battery.

His first post made it sound like the solenoid was always energized even though he disconnected the switch. At least that was my understanding.

eric1514 · 08-07-2021, 07:31 PM

Quote:

Originally Posted by mlafleur

OK, thanks. I found the following on-line. Must be the proper part. At $120CAN, it better be!

https://www.amazon.ca/-/en/Intellite...8353801&sr=8-1

Or this one for half the price.
https://www.amazon.ca/Cole-Hersee-24...8382640&sr=8-7

mlafleur · 08-08-2021, 07:30 PM

Quote:

Originally Posted by eric1514

Or this one for half the price.

https://www.amazon.ca/Cole-Hersee-24...8382640&sr=8-7

Ah, looks good to me. I’ll consider this one seriously.

M

mlafleur · 08-12-2021, 06:43 PM

Quote:

Originally Posted by mlafleur

Ah, looks good to me. I’ll consider this one seriously.

M

Alright, the part is ordered. I should get it next Tuesday. The the fun will begin... I’ll report here.

M

mlafleur · 08-31-2021, 05:45 PM

Hi all,
I finally went ahead and swap the battery isolator today. Bad news is: I'm not sure it was the problem. Once the old part had been removed, and the new one was in (see attached pic), I applied 12V to the small connectors (actuator?) of the old one, and I heard the selenoid click. I also started the engine and the voltage at the small connectors was still 0V (slenoid NOT engaged)

So it's back to square 1. Could someone validate my hypothesis that the purple wire (on the right) is actually bringing the signal from either the boost button or the engine running signal as in the crude diagram below?

Thanks.

M

You may also like: