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.

[red31]

GATJcampers wrote:
I pulled the J plug apart and measured straight out of the panel (probes on the J plug) got 20+ volts then reconnected that J plug. Then pulled the J plug after the controller that goes to the battery also got 20+ volts. Reconnected that J plug then with everything connected from panel to batteries I measured at the batteries and get about 13 volts.

as suspected!

If you slightly open the plug (so it is still connected) and probe the two contacts for voltage you will see something similar to battery voltage. Without the battery as a LOAD you are measuring open voltage ~20v.

That is one cheap controller that barely gets to 14.2 before going to float, BTDT, repeated undercharge! Get a better controller, cut off the plugs and hard wire to controller.

[pianotuna]

Measure the voltage post controller with the solar panels disconnected. It should read the same as the battery voltage.

If it does not, then there may be a wiring problem between the controller and the bank.

[LittleBill]

GATJcampers wrote:
I pulled the J plug apart and measured straight out of the panel (probes on the J plug) got 20+ volts then reconnected that J plug. Then pulled the J plug after the controller that goes to the battery also got 20+ volts. Reconnected that J plug then with everything connected from panel to batteries I measured at the batteries and get about 13 volts.

then your system is working. you need to give it time to get up to 14.2 or whatever its cut off is

[BFL13]

GATJcampers wrote:
I pulled the J plug apart and measured straight out of the panel (probes on the J plug) got 20+ volts then reconnected that J plug. Then pulled the J plug after the controller that goes to the battery also got 20+ volts. Reconnected that J plug then with everything connected from panel to batteries I measured at the batteries and get about 13 volts.

Now give it some time and watch the battery voltage rise. With the batteries already full it won't take long and the controller will drop back to 13. You should try it with the batteries down a little instead if being full.

[GATJcampers]

I pulled the J plug apart and measured straight out of the panel (probes on the J plug) got 20+ volts then reconnected that J plug. Then pulled the J plug after the controller that goes to the battery also got 20+ volts. Reconnected that J plug then with everything connected from panel to batteries I measured at the batteries and get about 13 volts.

[red31]

GATJcampers wrote:
The voltage coming out of the charge controller going to the batteries is the 20.2 volts I mentioned earlier.

is that with all the j plugs and ring terms connected, or are you pulling the connection apart to measure?

[grizzzman]

Look if there is 13. Volts at the battery and 20 volts at the output of the controller you have an open connection.

[GATJcampers]

The voltage coming out of the charge controller going to the batteries is the 20.2 volts I mentioned earlier. The solar panel came as a kit. Panel, charge controller, and wires to the battery. It is seriously impossible to hook up wrong.

[CA_Traveler]

Pull the battery J plug. What is the voltage on the side to the battery? IF 12V attach a light bulb. Does it light?

[GATJcampers]

I should have put this in the original post but I am almost certain it is wired correctly. From the solar panel to the charge controller is a set of J plug connectors that go to a picture that says solar panel. The other set comes out of the controller with a picture that says to battery(Another set of J plugs. That goes to the batteries that are connected with ring eyelets(on the correct terminals). It sounds like something is messed up with the system.

[pianotuna]

Order of connection should be controller to battery, then controller to panel(s)

[red31]

20v is right if the batteries are not connected / no load.

https://www.youtube.com/watch?v=JPb0b-s-Wfs

[Ed_Gee]

CA Traveler wrote:
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.

I agree! The output of the controller should be wired directly to the batteries. If the OP is seeing 20volts at the solar charger output and normal battery voltage at the batteries, then his wiring is definitely screwed up.

[naturist]

May I suggest a book and web site for your enlightenment? The Book.

The web site.

I learned a ton from them. Among the things I learned, is that the purpose of the charge controller is to take whatever the solar panels put out and make it compatible with your battery and the loads in the trailer. Another is that a single 100 watt panel is probably not enough to keep a 70-100 Amp Hour battery (array, in your case, with two 6 volt batteries) charged up, given that that 100 watts is the maximum possible at noon, in the summer, on a clear, cloudless day, and then only if the panel is perfectly oriented at the sun. You don't specify the amp-hour rating of your battery, but I suspect it is probably greater than 100 amp hours.

Check out the web site. Buy the guy's book. They will explain everything in simple terms.