System Troubleshooting

[vinylbob]

About 4 years ago I did some research and decided to build myself a solar panel. I bought my 3x6 cells from Ebay. When they arrived I checked the voltage and currents before soldered everything up producing a panel that I was proud of. I made an aluminum frame, cut a chunk of glass and encapsulated the cells in Sylguard. About that same time my life became a lot busier and the panel was put into the garage and sat until this past weekend.

I bought a cheap Coleman (Sunforce) 7 amp charge controller at the same time I built the panel.

Before I hooked everything up I checked the open circuit voltage with my multi meter and I am getting between 18-20 volts (sometimes a little higher) as well as 3 amps give or take. From what I remember this is about right.

Once I hooked the panel up to the charge controller, after hooking the battery up, Both of these lights come on and from what I understand only 1 should be on at a time.

"Charged" Light
"Charging" Light

http://www.amazon.com/Sunforce-7-Amp-Charge-Controller/dp/B0006JO0XI

The battery that I was using was a lawn tractor battery that was reading in the low 11 volt range. I also had another battery that I tried to see if it would make a difference and achieved the same result.

I have some more cells that are left over from the first build and would like to build another panel so I can have both of them charging a true deep cycle battery.

Is this system functioning ok or am I right in thinking that something is up.

Thanks in advance.

[Mike90250]

disconnect everything from the charge controller and wait 5 minutes. Then connect the battery first, wait about 30 seconds, for the controller to boot, then connect the PV panels and hope it works.

[vinylbob]

Thanks for the response mike. If there is enough light after work I will try this. If I end up achieving the same results are there any measurements I should take with my meter to start to figure out what the culprit may be? I have a second charge controller that I can get a hold of to see if that changes anything as well.

[vinylbob]

I have finally had some sun so I have made a video of how this is set up for testing. You can see how the panel is cutting out and the voltage ranges. I have also taken reading of the open circuit panel voltage.

Is this normal operation for this type of controller? I would have thought that the charge controller would allow a constant charge until the battery has actually reached that voltage. As you can see in the video the voltage spikes and then drops in cycles not allowing a constant charge.

https://youtu.be/Rw4nsksmH38

[inetdog]

The video explains as lot.

First, you have a very inexpensive and not particularly useful relay type controller. It is not what you need or want.

Second, the lights do not mean what you said. The top light means that the battery is charged enough that the panel has been disconnected. The bottom light means that the battery voltage is high enough that the load relay has been closed, putting battery power on the load terminals. Which you are not using, and would not need to use.

Third, you are measuring the panel voltage and you do not know what the readings mean.

When your panel is not connected to a load (relay open, top LED on) the open circuit will be at the Voc of the panel, in your case about 20V (you made a 40 cell panel??). That is fine for charging a 12V battery, but it means that at least 30% of the panel power will not be used for charging.
When the the panel is connected to the battery (through a relay so that there is no voltage drop) the panel voltage will equal the battery terminal voltage, with a very small offset for voltage drop in your wires (which may be too small). At the same time, when the battery voltage is high enough the Load relay closes (bottom LED on) and power is supplied to the Load terminals.
What we really need to see is what the battery terminal voltage is when the panel is disconnected and there is no load.
A "proper" charge controller will supply whatever current is necessary to get the battery voltage stable at the preset voltage.
Yours instead bangs on at full panel current, then turns off completely until the terminal voltage drops far enough. ]
The rapid cycling makes me suspect that your battery is shot, but only a measurement at the battery terminals instead will help confirm this. An open circuit voltage of 11V on a lead acid battery that has been sitting for days, weeks or months at that voltage means that it is at best a good boat anchor. (But be sure to remove the acid before using it that way. (that is a joke, by the way).

[vinylbob]

Thanks for the reply inetdog. Very much appreciated.
I have a lot to learn and I am glad there are people like you to help.
The panel is a 36 cell panel and that is the other charge controller that I borrowed. The other one I linked is one I originally purchased. I think the inner working are much the same as the results were pretty much the same.
I believe you are correct with that battery being shot. It came out of one of my old mowers and was the only one needing a charge.
As for charge controllers I'd be looking for something that would work with 2 of these panels as I have enough cells to make another panel. What would you suggest for a charge controller that won't be overkill for my set up?
I will be using a lead acid deep cycle battery but would also like to use this to keep my mower batteries topped up over the winter.
I'm also using this set up to add some light and power to my garden shed.

The lighting and power would be used seldom.

Thanks again.