16 replies to this topic

[Kodachrome]

If money is no object, I see there is a package at that link where they include the MorningStar Sunsaver Duo, it charges 2 battery in a priority you determine. Then you do not need to choose :-)

Yeah, but that still leaves the truck charging aspect. Besides, it is not MPPT and the terminals for the panel inputs are not very big, I have two sets of leads going into it.

Now, what if I want to have the option of running my DC camper needs like the fridge while driving when charging either battery via the truck? Sounds like another breaker switch...

[K7MDL]

...
Now, what if I want to have the option of running my DC camper needs like the fridge while driving when charging either battery via the truck? Sounds like another breaker switch...

The truck charging was taken into account in the last solution proposed. The battery switch will allow charging either or both batteries from the truck if it is running. I also assumed you will have a standard truck/camper battery isolator/relay installed. The DC panel and fridge are wired to the Diehard which is helped by solar (which should have a protection fuse anyway, but can be out of the way, and within several inches of the battery). So you can select the switch to the Diehard and all loads run off the truck when running, solar charged battery when not, Optima is isolated in standby. Flip the switch and the Optima gets charged by the truck, and the loads run off the solar+Diehard exclusively.

The fuse/breaker manipulation was only required for the odd case where you wanted to solar charge the Optima rather than the Diehard. In most cases I do not think you would bother though, just run the truck (or find AC) if things are that far gone.

Seems like this covers 99% of your needs stated. If not them might as well get matched 6V golf cart batteries. :-)

[Kodachrome]

The truck charging was taken into account in the last solution proposed. The battery switch will allow charging either or both batteries from the truck if it is running. I also assumed you will have a standard truck/camper battery isolator/relay installed. The DC panel and fridge are wired to the Diehard which is helped by solar (which should have a protection fuse anyway, but can be out of the way, and within several inches of the battery). So you can select the switch to the Diehard and all loads run off the truck when running, solar charged battery when not, Optima is isolated in standby. Flip the switch and the Optima gets charged by the truck, and the loads run off the solar+Diehard exclusively.

The fuse/breaker manipulation was only required for the odd case where you wanted to solar charge the Optima rather than the Diehard. In most cases I do not think you would bother though, just run the truck (or find AC) if things are that far gone.

Seems like this covers 99% of your needs stated. If not them might as well get matched 6V golf cart batteries. :-)

So I am going to get this up and running soon. Question though, will I be able to read the optima / backup battery on the camper water / battery gauge when the load is pulling off of that battery?

And how could I possibly have a separate gauge for the optima so I can check to see how full it is when it is getting juiced up by the truck?

[Kodachrome]

A BIG thanks to K7MDL for all the help, I got it wired today and it seems to be working fine. Now I can run two batteries if needed, if one craps out, I don't have to replace both since they are not in parallel. Found a nice & simple battery monitor for the Optima / Backup too:

http://www.ebay.co.u...874&refid=store

Nothing like a little overkill...

[Gerdo]

It doesn't sound like the two camper batteries are tied, electrically, together. But... If you do have two different batteries (type, size, brand, and even down to different build lots) They will always have different charge states. These differences will cause the lower charged battery to "charge" it's self of the other battery. This will go back and forth between the two batteries causing both batteries to discharge.

[K7MDL]

A common strategy to deal with this is the ACR, automatic charging relay, or voltage sensing relay. It monitors the primary battery voltage and after it is reasonably charged and receiving excess charge source, then connects the secondary (aux, house) battery and it rises in voltage as it charges.

As along as the charge source is present, and at a higher voltage, the 2 batteries tied together are not really interacting (of any concern if they are healthy). So being tied together is mostly a concern for discharging batteries, or batteries at rest. The ACR solves that by separating them when the charge voltage goes away and battery voltage drops.


The solution used by Kodachrome only has the batteries separated as you guessed, but the "Both" switch position can be used to have one boost another. Not a scenario likely to be used. Having a manual overide on an ACR is handy to use the camper battery to boost your starter battery if you happen to leave your lights on and need a jump someday. No AC generator DC cable or jumper cables required.

[MakersTeleMark]

I've used my "both" setup coupled with my ACR 3 times in the last two weeks from being in a place where I couldn't plug in, and cycling the glow plugs was pulling a ton off of my 2 1000 ca batteries in the truck. When I "both it", I get my optima on board, which is charged by the solar panel, and she with the other 2 can fire those plugs no problem until I get that happy puff, cough, puff of smoke coming out of the exhaust.

Very handy indeed.