Quote:
Originally Posted by rotor_wash
Actually Harvey, my controller does have a unique way of increasing power from the panel. I have a specially built panel that includes one extra row of cells that in theory will allow the panel to generate over 21VDC. The matched controller takes the excess voltage and with a bit of loss to heat, increases the amperage to the battery bank. On a good day I will see just over 6 amps from the panel that is converted to 7.5 to the battery. At least that's what the LCD says.
Since you store your TM indoors, you might benefit from Bill's portable method. I see you have lots of experience with solar, but if I'm not there to monitor it, I have a good controller that will.
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I didn't mean for this to be a battle of the controllers.
I realize that they have their place and there are good reason's for
some to have them, especially if the array out-weighs the batteries. That's just simply not my case.
With my panels, my usage and my batteries, there is simply no need of a controller....for
ME......I'd rather have the panels putting 100% of their available output into the batteries 100% of the time.
BTW....most any solar panel will put out 21VDC (open circuit) if you put the voltmeter on the leads to the panel while it isn't connected to a battery. As soon as you connect the leads to the battery, the voltage will drop to just a volt or 2 above the batteries current voltage. As the amperage reaches capacity in the battery and the battery voltage increases, the difference between the battery being disconnected from the array and the voltage with it connected, will become closer. In other words, if you attach a solar panel to a battery that is reading 12.0V, a large enough array may take the voltage reading up to 13.3 or 13.8 (approx 1.5V increase) almost immediately. However, if you attach that same array to a battery that reads 12.7V, you will still only see 13.8 to 14V, a difference of about .9V (at least at first). It's kinda like filling a tire with air with a small compressor. The higher the pressure in the tire, the less effective the compressor.
If you have a solar panel that "includes one extra row of cells that in theory will allow the panel to generate over 21VDC" that simply means that one row of cells is cut-off part of the time while charging. Again, the controller cannot increase panel output. It's simply impossible. The only thing that a controller can do is turn a panel (or in your case, a part of the panel) off and on. This may make the final stage of charge more effective but I doubt that I will be concerned about the final state of charge while camping because my batteries will be in an almost constant state of discharge.