Hello all,I have a unisolar 136 watt panel and a morningstar prostar 30 controller. IF I run the wires from the panel down the convenient place above the controller were there are already holes it will add about 5' from the panel to the controller. Then I could easily splice the pos from the controller to the battery cable near where it comes out of the floor to the converter. The neg could then be attached to the bus near the converter. This is probably 5' from the battery and 18" or so from the converter. The other option is try to run the wires down the front of the trailer to the controller and then to the battery. This will save some run to the battery but it will be a HUGE PITA and will require a lot of drilling into areas that I have no idea what is behind it and tearing some of the fabric off the bottom of the rv to find it near the water tank. So the question is this. I am willing to loose a little bit of voltage from the longer run, I only use the batts to run the lights and furnace blower and I am mostly just interested in keeping the batt charged when I'm not there but is there a problem with splicing the wires front the controller to the battery cables closer to the controller? This would be a very easy job and wouldn't require any drilling.Thanks

It's always best to make the controller to battery wire run with as large a wire and shortest distance as possible. However, for what you describe it will make very little difference for essentially a system being used primarily as a battery maintainer. Also with the ProStar you have ability to run battery sense wires which will make up the difference for slight voltage loss on the battery cables as the ProStar will controll voltage off those sense wires and raise charge voltage to compensate for the charge wires loss. I also use a ProStar controller

I have 4AWG cables going between my Converter/charger and batteries. I will mount a BLUE SEA BUS BAR TERMINAL STRIP where the SOLAR cables will hookup. I like all of my battery connections to use proper RING TERMINALS. Makes for easy removal for troublshooting or changing things...Roy Ken

You can connect any where you wantBut max voltage and max charge are archived when using the shortest wire run possibleI have a long wire run and I do not get as much charge as other members with the same amount of solar, in some cases members with less solar get more amp hrs than I doDo it your way, and be ready to change it if the batteries are not getting fully chargedI'm not condemning your actions, but I would (and did) run new wire all the way to the batteries, Mine was still a long run, but I ran #4 ga wire, which is very likely larger than what is connected to your converter, (you Will be lucky if it's 6 ga) and I should have used something larger

Hi,A long run can be compensated for by battery voltage sense wires.

Thanks again but I hosed myself. I got the controller installed and wired to the battery cables and was going to hook up the solar panel to make sure it worked before I stuck it on the roof and I got the wrong connectors on the extension. I noticed about 30 seconds after I cut in in half. Now I've got to order a new extension and try to sell the other one. Mostly I'm mad at myself because I brought the camper home mostly for this project and now I'll have to do the rest of it later.

Connect cables from solar closer to converter than batts?

16 Replies

Shadow_Catcher
Explorer
May 25, 2014
This is a high voltage panel Vmp 33V nominal 24V so voltage drop is not as important, you could get away with 10ga wire. HOWEVER you may be exceeding the input voltage of the controller with the Unisolar panel. I chose a Steca controller which was the only PMW controller that would handle the voltage from my Unisolar 144W panel. You may have to move to a Morningstar MPPT controller or a Steca.
Fixed_Sight_Tra
Explorer
May 24, 2014
Thanks again but I hosed myself. I got the controller installed and wired to the battery cables and was going to hook up the solar panel to make sure it worked before I stuck it on the roof and I got the wrong connectors on the extension. I noticed about 30 seconds after I cut in in half. Now I've got to order a new extension and try to sell the other one. Mostly I'm mad at myself because I brought the camper home mostly for this project and now I'll have to do the rest of it later.
pianotuna
Nomad III
May 24, 2014
Hi,

A long run can be compensated for by battery voltage sense wires.
MrWizard
Moderator
May 24, 2014
You can connect any where you want
But max voltage and max charge are archived when using the shortest wire run possible

I have a long wire run and I do not get as much charge as other members with the same amount of solar, in some cases members with less solar get more amp hrs than I do

Do it your way, and be ready to change it if the batteries are not getting fully charged

I'm not condemning your actions, but I would (and did) run new wire all the way to the batteries,
Mine was still a long run, but I ran #4 ga wire, which is very likely larger than what is connected to your converter, (you Will be lucky if it's 6 ga) and I should have used something larger
RoyB
Explorer II
May 24, 2014
I have 4AWG cables going between my Converter/charger and batteries. I will mount a BLUE SEA BUS BAR TERMINAL STRIP where the SOLAR cables will hookup.

I like all of my battery connections to use proper RING TERMINALS. Makes for easy removal for troublshooting or changing things...

Roy Ken
hmknightnc
Explorer
May 24, 2014
It's always best to make the controller to battery wire run with as large a wire and shortest distance as possible. However, for what you describe it will make very little difference for essentially a system being used primarily as a battery maintainer. Also with the ProStar you have ability to run battery sense wires which will make up the difference for slight voltage loss on the battery cables as the ProStar will controll voltage off those sense wires and raise charge voltage to compensate for the charge wires loss. I also use a ProStar controller

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Connect cables from solar closer to converter than batts?

16 Replies

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