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 > Can I charge the house battery with the engine alternator?

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heyobie

Maryland

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Posted: 11/11/22 06:09am Link  |  Quote  |  Print  |  Notify Moderator

I have a Class C, 1988 Ford 350 Travel Master with one good house battery. When I boondock in cold weather, my propane furnace can get me thru 1 night. If I want to drive to another non electric spot,I'm out of electric and therefore heat.

I am considering adding another house battery as a solution. But I want to know if it is a simply solution to charge my house battery using the engine alternator.

Also, a battery cable has been run from the house battery into the engine. It is terminated in the engine bay but not connected to anything. It looks like factory work. Maybe a factory option.

Thanks for looking

SoonDockin

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Posted: 11/11/22 07:07am Link  |  Quote  |  Print  |  Notify Moderator

Look at Victron Energy Orion DC to DC chargers. Depending on how many amps your alternator puts out, they likely have one that will work.


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MDKMDK

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Posted: 11/11/22 07:34am Link  |  Quote  |  Print  |  Notify Moderator

It's probably already set up to do that, via a battery isolator or separator. Just add the 2nd battery, connected in parallel. Some will suggest you replace the original coach battery with an identical FLA to the new battery to balance the load.


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time2roll

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Posted: 11/11/22 07:49am Link  |  Quote  |  Print  |  Notify Moderator

Virtually all RVs are set up to charge the house battery from the engine alternator. Sounds like the system was modified and eventually left disconnected. Commonly there is an isolator to allow charging while the vehicle is running and prevent discharge of the chassis start battery when parked. Need to reconnect or create a new connection. Second battery is a must and might not even be enough.

Charging through the alternator is generally slow due to limited power and long thin wires. A DC-DC charger can really help. Can still take 12+ hours to get a low battery fully charged.

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bobndot

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Posted: 11/11/22 07:54am Link  |  Quote  |  Print  |  Notify Moderator

https://www.rvidiots.com/does-an-rv-battery-charge-while-driving/

Dc to dc would most likely charge better and faster while driving.
You could use s small 1000 inverter generator at a campsite as well.
That will run your converter which will charge the house.

MDKMDK

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Posted: 11/11/22 08:04am Link  |  Quote  |  Print  |  Notify Moderator

That homeless battery cable in the engine compartment was probably attached to a battery isolator, that probably failed and was never replaced. Many older motorhomes put them in the engine compartment area for ease of access to the chassis battery for connectivity. There would usually be 3 connections on it, one for the alternator feed in and 2 out to the chassis/coach batteries. The chassis circuit was often run through a diode, to prevent reverse current traffic from the chassis battery, while drawing from the coach batteries, as others have suggested.

camperdave

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Posted: 11/11/22 08:11am Link  |  Quote  |  Print  |  Notify Moderator

sounds like the wiring is already there, add a battery isolator at the engine side of that battery cable coming from the house and wire it up to the starter battery.

Yes a DCDC would charge quicker, but a simple isolator is like $50 vs $150+ for a DCDC. And since your RV is older, it probably won't have a smart alternator so it will charge quicker than the newer RV's do.


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enblethen

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Posted: 11/11/22 08:17am Link  |  Quote  |  Print  |  Notify Moderator

Many rigs used a diode type battery isolator similar to this one. They are not as good as a relay based unit like this. Battery switch


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heyobie

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Posted: 11/11/22 09:20am Link  |  Quote  |  Print  |  Notify Moderator

Thank you guys for all the info.

There is more to the story. I didn't want to glog up my post but since I have found interest and intelligence, someone may be able to explain this.

The large positive wire comes from the house battery to a post on a selenoid which is mounted on the driver side wheel well. Then on the opposite side of the selenoid, another large red positive wire goes up and across a plastic channel over to a block attached to the passenger fender. My guess is that this is all factory but not sure. But what is not factory is a push button has been installed inside the cab on the dash. It connects to the selenoid and a power source. The push button doesn't work, but the purpose was to activate the selenoid so that the house battery power would run over to the car battery/passenger side of the vehicle.i thought it may have been a system to use the house battery to start the car. Maybe someone can explain what it is. I'm gonna pull it since it has no purpose it seems. This is probable the battery switch, but why it has a push button makes no sense to me

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Posted: 11/11/22 09:29am Link  |  Quote  |  Print  |  Notify Moderator

heyobie wrote:

Thank you guys for all the info.

There is more to the story. I didn't want to glog up my post but since I have found interest and intelligence, someone may be able to explain this.

The large positive wire comes from the house battery to a post on a selenoid which is mounted on the driver side wheel well. Then on the opposite side of the selenoid, another large red positive wire goes up and across a plastic channel over to a block attached to the passenger fender. My guess is that this is all factory but not sure. But what is not factory is a push button has been installed inside the cab on the dash. It connects to the selenoid and a power source. The push button doesn't work, but the purpose was to activate the selenoid so that the house battery power would run over to the car battery/passenger side of the vehicle.i thought it may have been a system to use the house battery to start the car. Maybe someone can explain what it is. I'm gonna pull it since it has no purpose it seems. This is probable the battery switch, but why it has a push button makes no sense to me

Sounds like a "battery boost" system, which allows you to borrow some cranking amps from the coach battery, if the chassis battery is too low to start the engine. The push button would connect the 2 systems for the duration of the starting attempt, allowing current flow from the coach battery to "help" the chassis battery turn the engine over. They're still fairly common on modern motorhomes.

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