My Twin+ Battery Setup

[racedaymechanic]

I added a second deep cycle Battery to my Sabre for boondocking, we are only 45 miniutes from The Blue Ridge Parkway and go there often during the summer, we have a generator but don't like to run it so I added a battery and Inverter so we can watch TV and do other things at night, I can turn the inverter on and off from inside the Camper and I put a switch on the circuit the wall outlets are on so I can switch from shore power to the inverter on just those outlets, I put a plug so I can add a bank of batteries to the system if need be, I also put a Deutsch connector so I can plug a 1.5 amp charger to the Batteries without it going thru the onboard charger, I made a tray out of 1 inch angle iron for the batteries to sit in

 

[Cajun Po-Boy]

Nice setup...Thanks for sharing with pics!

 

[Herk7769]

While very neat, with a bit of a mod your set up would be perfect. Managing charge state of each battery and balancing recharge cycles would be a lot easier if the current flow through the batteries (in and out) were the same.

By hooking up the batteries with the camper's (and inverter's) ground and positive feed connected to the same battery's terminals, the second battery's resistance is increased by the length of the wires connecting it to the first.

This imbalance of resistance will decrease amperage from the higher resistance battery when using it; throwing the wattage demand for the balance on the "close" battery. Same with charging; the lower resistance battery will receive more charging current that the higher resistance battery and will be out of sync cycle-wise.

The effect will be the closer battery working harder and wearing out faster than the "loafing" battery.

By balancing the resistance evenly between the batteries, it will be easier to keep them working the same. This is done by using wire length and internal battery resistance as what drives the wiring scheme. If you reference the attached drawings for wiring a 2 (12 volt) battery system, you will see that the resistance through both batteries is identical.

 

[racedaymechanic]

While very neat, with a bit of a mod your set up would be perfect. Managing charge state of each battery and balancing recharge cycles would be a lot easier if the current flow through the batteries (in and out) were the same.

By hooking up the batteries with the camper's (and inverter's) ground and positive feed connected to the same battery's terminals, the second battery's resistance is increased by the length of the wires connecting it to the first.

This imbalance of resistance will decrease amperage from the higher resistance battery when using it; throwing the wattage demand for the balance on the "close" battery. Same with charging; the lower resistance battery will receive more charging current that the higher resistance battery and will be out of sync cycle-wise.

The effect will be the closer battery working harder and wearing out faster than the "loafing" battery.

By balancing the resistance evenly between the batteries, it will be easier to keep them working the same. This is done by using wire length and internal battery resistance as what drives the wiring scheme. If you reference the attached drawings for wiring a 2 (12 volt) battery system, you will see that the resistance through both batteries is identical.

Actually If you look close thats how I have mine,
I build and sell Wiring for Race Cars and Diesel Trucks, I have about 15 Nascar Teams that I build Harness's and Battery Cables for

 

[Herk7769]

Actually If you look close thats how I have mine,
I build and sell Wiring for Race Cars and Diesel Trucks, I have about 15 Nascar Teams that I build Harness's and Battery Cables for

Yup, it was hard to see the ground wire. But now that you pointed it out I see where it was connected.