Battery Isolator

I recommend you install a Sure Power 1315-200 Battery Separator. I put one in when my isolator died. I am completely happy with it. Really simple installation and the auto battery combine on start is great.

Jose

Kohldad,

You have a very common problem, so, do not be surprised that there is a good solution at hand. I installed a few of these before the depression killed our boat work business.

Go To Yandina and scroll down the page. There are two models that could work, but the 100 amp has wires that can't be shortened and that is why you might consider the 160 amp version. Either will do. Read the downloadable manuals before you decide.

These devices are interesting. When charging power exists, it parallels the two batteries. When the voltage drops below charging levels, it separates them. They require no other modifications to the existing systems.

Matt

The relays the switches control is a standard 40A automotive relay which is rated for continuous duty. These are not the big solenoid type relays used for 150A type service.

For $130 option, it is probably the best bang for the buck you can get on a truck where you plan on adding options requiring power. The option provides a PDC (power distribution center) with relays and individual fuses controlled by in-cab switches. More info: Ram Aux Switch

kohldad wrote:
Yes, 20A/hr total overnight usage.

So it looks like everyone is saying just KISS and go with a standard relay. That makes things so easy for me.

When I ordered my truck, I added the Aux Switch Package which provides five switches in the dash. Each switch controls a relay in the engine compartment. Two of these circuits are rated at 40A and accept up to a #6 wire. Nice thing is the switches are programmable to be on all the time (battery) or ignition on additionally they can be set for momentary, on/off, or last state.

So by setting one of the switches to ignition and last state, whenever I load the camper, just turn the switch on and forget about it until the camper comes off. The circuit will only be active when the ignition is on.

My current camper only has one battery but my next camper may have tow and that is the worst case I will ever see. But the 40A circuit will still be plenty for a dual battery setup.

Not a standard relay as in the type often used for starting. You want a continuous duty. They are used on golf carts, fork lifts, industrial type applications.
I would go with a good brand for long life and not have a fire hazard.

This is just an example as you may find heavy rated when you search
Cole

All I use is a simple continuous duty relay/solenoid which cost me about $15.

My truck doesn't have a camper package so it only has the plug at the rear of the truck.

I have tested using the rear plug and can only charge about 5A with everything off in the camper. When I use the fridge in DC mode, the circuit cannot provide the 10A necessary for the fridge, much less charge the battery at the same time.

I also tow a trailer on occasions so need a rear plug for it. Realize I could use a Y pigtail, but don't want to.

Plus, when I add the plug in the front of the bed for the camper, the run between the two batteries will be shortened, the wire gauge will be increased, and the connector will be heavier duty - all of which will increase charge rate.

If your new truck has the 'camper package' it should already have a dedicated charge circuit built into the 7 way trailer plug.

Why create a second parallel system to do the same thing?

Yes, 20A/hr total overnight usage.

So it looks like everyone is saying just KISS and go with a standard relay. That makes things so easy for me.

When I ordered my truck, I added the Aux Switch Package which provides five switches in the dash. Each switch controls a relay in the engine compartment. Two of these circuits are rated at 40A and accept up to a #6 wire. Nice thing is the switches are programmable to be on all the time (battery) or ignition on additionally they can be set for momentary, on/off, or last state.

So by setting one of the switches to ignition and last state, whenever I load the camper, just turn the switch on and forget about it until the camper comes off. The circuit will only be active when the ignition is on.

My current camper only has one battery but my next camper may have tow and that is the worst case I will ever see. But the 40A circuit will still be plenty for a dual battery setup.

moved from technology corner

I installed a 100 amp maximum rated forklift solenoid, rated at 100,000 on-off cycles before failure. It has silver allow contacts too!

Grainger #6C017

I run it with the same power that turns on and off the radio, as it was handy to reach that wire under the dash of my motorhome, and use that to turn on the relay.

On my motorhome, I ran #4 wire (rated at max 100 amps or so) directly from the alternator (where you will have close to 14.8 volts when the truck first starts) to the relay, to the coach battery bank. IN my case I have 4 golf cart batteries, rated at 440 amp hours at 12 volts. I was able to move as much as 40 amps per hour, so I would suggest fusing it at 50 amps or 60, due to the #4 or #2 wire being rated at well over 100 amps.

You can use a pair of 30 amp automatic reset circuit breakers. Or find a 60 amp at a Napa dealership? In my RV, they use pairs of the 30 amp to get a 60 amp circuit. The 30 amp is much less expensive than a 60 amp.

You might want to use something like a 'anderson connection' or use a 3 phase twistlock 30 amp connector (they will have 4 poles including the ground and you can connect the negative lead to the ground and the wire opposent the ground, then use +12 on the other two leads, so you can get 60 amps through the 30 amp connector without overloading it)

Good luck,

Fred.