Does alternator charge house batteries?

[Jeff00NTW]

Hello,

Trying to figure out if the alternator charges the house batteries while driving.

I know when on shore power or on generator, they charge both the house and chassis batteries.

Do not know if National put in a solenoid for the alternator to charge the house batteries when running?

I do have the battery boost switch on dashboard, which I know bridges the batteries for starting.

Does anyone know if this model and year (in signature) has this option?

Thanks

[twinboat]

Its rare to find a MH that doesn't charge the house battery while running down the road.

Your boost solenoid may double as a charging relay, as most modern MHs do but some of the older models us a solid state battery isolator.

They are 3"×6" box's with 3 heavy wires and cooling fins on them. If equipped most are near the boost solenoid.

[winniman]

Easiest way to tell is start the rv, and test both sets of batteries. If they both read around the same, { should be high `13s volt to 14 volts}, it does. Any rv Ive had or seen of my friends all do. Some dont charge the engine batteries while plugged into shore power.

[Richard S.]

On National RV's the interconnect solenoid is on the back side of the Battery Control Center board and it looks like the old FORD starter solenoid, but it is not. It is a continues duity solenoid.

[garym114]

This interconnect solenoid should close and connect the two systems when either the house or chassis battery system gets to 13.2 volts. Doesn't make any difference where the charging is coming from.
This is called battery boost when you manually operate it from the dash.
It will open open when either gets to 12.8 volts.
__________________

[Jeff00NTW]

Thanks everyone,

I found the solenoid, behind the battery control center. Looks like a canister that looks like it has three wires coming from it.

I will start the rv and see if it will charge house batteries.

Not sure if I missed this, but does the solenoid activate to charge the house batteries when the chassis batteries hit a certain voltage?

And if the house batteries are not charging from alternator, I am guessing it is a bad solenoid?

Thanks

[Jeff00NTW]

I tried this also,

I have it hooked up to shore power right now and it is charging house batteries and the voltage is at 13.36 volts, but the chassis batteries are at only 12.20 volts.

I see from reading around that the solenoid should trip around 13.2 volts?

So I am guessing that the solenoid is not working properly?

Thanks

[RROLDSX]

Shore power does not charge the chassis battery unless you have an auxiliary battery charger for it.

[twinboat]

Although the solenoid may be activated, in many cases the internal contacts get burnt and don't pass the current.

Many older MHs don't have bi-directional charging. The solenoid only works with charging from the chassis battery to the house bank.

The chassis battery typically needs to charge up to about 13. 4 volts before the solenoid closes to also charge the house bank.

If you don't have the seperate charger to maintain your chassis battery, while on shore or generator power, there are a few devices that will cure that.

Tri K L Start, Ample L Start, and a few combiner relays like a Cyrix 100 or a Yandina combiner. Any one of them can be wired to both sides of the solenoid.

Another option is a BIRD device to control the solenoid you have.

https://www.intellitec.com/index.php...llitec_B.I.R.D.

Last, is a complete new solenoid with the bi-directional control on board.
https://www.yandina.com/c600Info.htm

[Jeff00NTW]

Originally Posted by RROLDSX

Shore power does not charge the chassis battery unless you have an auxiliary battery charger for it.

Is there a way to have the shore power charge the chassis batteries? I thought this is what the interconnect solenoid is suppose to do? Maybe I am missing something?

Not sure if I am getting this right? The alternator will only charge chassis batteries when running. And shore power or generator will only charge house batteries. So the solenoid's only use is to connect both sets of batteries when pushing the battery boost on dash to help start the engine or generator if one of the battery banks is low? And not to connect both banks of batteries for charging? Hope this make sense.

Thanks

[Jeff00NTW]

Originally Posted by twinboat

Although the solenoid may be activated, in many cases the internal contacts get burnt and don't pass the current.

Many older MHs don't have bi-directional charging. The solenoid only works with charging from the chassis battery to the house bank.

The chassis battery typically needs to charge up to about 13. 4 volts before the solenoid closes to also charge the house bank.

If you don't have the seperate charger to maintain your chassis battery, while on shore or generator power, there are a few devices that will cure that.

Tri K L Start, Ample L Start, and a few combiner relays like a Cyrix 100 or a Yandina combiner. Any one of them can be wired to both sides of the solenoid.

Another option is a BIRD device to control the solenoid you have.

https://www.intellitec.com/index.php...llitec_B.I.R.D.

Last, is a complete new solenoid with the bi-directional control on board.
https://www.yandina.com/c600Info.htm

Great. thanks for the info. Is there a device that can be used when the engine is running that the alternator will also charge the house batteries while it is charging the chassis batteries? The main problem I see is that my house batteries are agm batteries compared to the normal chassis batteries.

[Richard S.]

It sounds to me like you need to change out the solenoid. I had about the same condition, changed the solenoid and every thing works just like it was new.

[Skiddy]

have you verified that the alternator is Not charging the house batteries?
on mine the house batteries charge on shore power, generator and alternator.
for the chassis batteries are charged with shore alternator and generator only.
just found all this out a couple weekends ago when my chassis batteries went dead. I am going to put a maintainer on the chassis batteries as there isn't a lot being used on 12V only while camping.

[RROLDSX]

That’s correct.