Understanding solar

[GATJcampers]

I am trying out solar for the first time. I have a toy hauler with 2 brand new 6 volt batteries wired in series. I got a 100 watt solar panel with a 11 amp charge controller that cuts in at 13v and cuts out at 14.2v.I hooked it up and my readings confuse me. Out of the panel I read 20.2 volts then out of the controller I read the same 20.2 volts but at the batteries I read from 12.7 - 13 volts. Don't understand why. There absolutely no load on the trailer at all, could that be why? Shouldn't the volts be between the cut-in and cut-out voltage? I boondock the majority of the time so I want to get the most out of it. Any insight or knowledge you can share would be great. Electrical is my worst topic so break it down, it won't insult me. Thanks in advance.

[CA_Traveler]

He posted 20V at the controller output and 13V at the batteries. If he's measuring the same set of wires on both ends then the wiring is faulty. Miswiring could also produce strange results.

[Lwiddis]

Did you do an energy survey...actual AH use or desired AH use...before you bought anything? Otherwise you’re stabbing in the dark with your money and time. An 11 amp controller isn’t very useful. Start over with the survey. Few boondockers have only one 100 watt panel.

[time2roll]

If the controller output is connected to the batteries the voltage should be about the same.
Check your connections.

[BFL13]

You have mixed up your wiring IMO. I disagree with above idea that your solar set is junk, just because you can buy better ones.

Your panel when disconnected and aimed at the sun will have around 20v at the pigtails

If you connect the controller to the battery and then the controller to the panel aimed at the sun, you will now see battery voltage 13-15 whatever it is at the time at the panel and at the controller "input".

Your situation appears to be that the controller is on the panel and not the battery. You might even have the panel wired into the "battery" connections instead of the "array" connections. Do not use the "load" connections at all (if any in that controller)

[CA_Traveler]

Sounds like a open wire or fuse from the controller to the batteries.

Measure the amps likely 0A.

[grizzzman]

GATJcampers wrote:
I am trying out solar for the first time. I have a toy hauler with 2 brand new 6 volt batteries wired in series. I got a 100 watt solar panel with a 11 amp charge controller that cuts in at 13v and cuts out at 14.2v.I hooked it up and my readings confuse me. Out of the panel I read 20.2 volts then out of the controller I read the same 20.2 volts but at the batteries I read from 12.7 - 13 volts. Don't understand why. There absolutely no load on the trailer at all, could that be why? Shouldn't the volts be between the cut-in and cut-out voltage? I boondock the majority of the time so I want to get the most out of it. Any insight or knowledge you can share would be great. Electrical is my worst topic so break it down, it won't insult me. Thanks in advance.

At best around noon you "may" never see over 5 amps output. If you are using more then battery voltage may never go higher. The battery decides output voltage when the battery is low. The charge controller is garbage.
Do your homework and buy a good controller.
Good luck with your adventure!

[pianotuna]

It sounds as if you are using a PWM controller with a high voltage panel. To do that correctly an MPPT controller needs to be used.