how to hook up dual batteries in motorhome

The bad part about using the storage bay is in most cases is usually directly under your sleeping bed... That would bother me having something that might explode directly under my bed. That also includes propane tanks mounted close o the sleeping beds. Sometimes you have to just live with things the way they are I guess...

I've mounted it in the bay that is under the kitchen table seat right behind the driver's seat. If it blew up it would have to blow through the steel body of the compartment and through the storage area under the kitchen table bench seat before it reached the person sleeping there.

But no one ever sleeps there anyway.

Steve

I've vented the compartment and nothing else is in that compartment but the poop tube.

If you switched to AGM or Gel cell batterys it would not matter where you put them. They are sealed, can be mounted upright, on their sides, on their ends, even upside down. None of this watering nonsense to worry about.

Of course if you are working with lead acid batteries they have to be in a location that is vented to the outside and also able to contain any boiled out fluids or allow for drainage directly to the ground.

Keeping the batteries together is always a good idea.

The bad part about using the storage bay is in most cases is usually directly under your sleeping bed... That would bother me having something that might explode directly under my bed. That also includes propane tanks mounted close o the sleeping beds. Sometimes you have to just live with things the way they are I guess...

Roy Ken

Why not move both batteries to the compartment?

I suppose I could, but that would have been more work and expense. I'd have to buy another battery box.

Also, I'm not sure how much weight the compartment can support. It's really just a big sheet metal box.

On the upside, I could upgrade to a larger battery. I put a big one in the compartment - the one under the hood is limited in size by the space available.


Steve

Hi,

Why not move both batteries to the compartment?

maillemaker wrote:
I have a question.

I installed a second battery in my RV. It's a class C with one engine battery under the hood and one house battery under the hood.

There was no room for a second battery under the hood, so I installed one in one of the underbelly storage compartments. I put it in a battery box and bolted it down securely.

I ran cable from the + of the original battery to the + of the new battery, and likewise for the - terminals. I realize this is not the balanced way to do it, but it results in only 2 20-foot cables running from one battery to the next.

If I do it the "balanced" way, I will need a 3rd 20-foot cable coming from the new battery back to the engine compartment.

Is the savings of the more efficient, balanced installation offset by the resistance of the 3rd 20-foot cable run that will be required?

Steve

I have a question.

I installed a second battery in my RV. It's a class C with one engine battery under the hood and one house battery under the hood.

There was no room for a second battery under the hood, so I installed one in one of the underbelly storage compartments. I put it in a battery box and bolted it down securely.

I ran cable from the + of the original battery to the + of the new battery, and likewise for the - terminals. I realize this is not the balanced way to do it, but it results in only 2 20-foot cables running from one battery to the next.

If I do it the "balanced" way, I will need a 3rd 20-foot cable coming from the new battery back to the engine compartment.

Is the savings of the more efficient, balanced installation offset by the resistance of the 3rd 20-foot cable run that will be required?

Steve

That is method #3 and is equal to method #2 with twin batteries. For even numbers of jars four or greater method #3 or #4 will be optimal. For odd numbers of batteries only method #3 will be balanced.

The article does say that #2 can't be improved on for twin 12 volt batteries.

Thanks for the tip

We hooked up 2 batts in our fifth wheel.
Two battery boxes size 27-31 from Walmart $7.97 each.
2 Maxx deep cycle batts size 29 from Walmart 99.97 each.

Pos to pos neg to neg thru a battery switch (or not).
We get 3 to 4 days of DC power running various lighting the heater at night and a 300 watt Samlex inverter for the television and blue-ray no sweat.

Easy stuff don't let it become complicated with diagrams and other confusion.

And if you use a battery switch that has 1- 2 or both, you can use a portable charger and charge both banks at the same time . Also if one battery goes bad you can isolate it.