For a small solar set up, to just run one 12V diaphragm pump you will be better off using a PWM controller. PWM is pulse width modulation, they are far lower cost and very adequet for that use. If the pump calls for 12V at 3 or 4 amps, just get a 12V deep cycle battery, to run the pump and a 60-100 Watt panel with a PWM controller to maintain the battery, it will work fine. Keep in mind that the solar panel needs sun exposure, place it where it will in fact get enough sun. Also you might want a second deep cycle battery to swap out if you have a period with too little sun, or too much snow on the panel. Battery, don't get a LiFePo4 battery for this use, they can't be charged at sub freezing temps. You are likely best off using a FLA (flooded lead acid) or an AGM (absorbed glass mat) or a Gel battery. The first choice requires checking electrolite levels about every 2 weeks in this type of use, and refilling as needed with distilled water, the other 2 don't need anything except maintaining clean contact with the wiring connections, but the cost more to buy.
If you were to use an MPPT (maximum power point tracking) controller, you would need a larger solar panel and maybe larger battery, they consume power 24/7, a PWM only uses power when it's controlling the solar output into the battery.
My history, I bought 16 LiFePo4 batteries each was 3.3A and 200 WH (watt hour) wired in series. For use in my largew solar system in my sugarhouse. When new they cost $2500+ total. I then added a 65 watt heating pad and a full 1" insulation foam enclosure to maintain battery temperature plus a BMS (battery management system) which was susposed to shut the charge off at 34F so the batteries would not be charged below that temperature. Long story short, the BMS failed and the $2500+ battery bank was ruined, they could not be charged ever again, despite several attempts at various voltages and amperages. They were junk. I have now replaced them with AGM batteries.
My solar is actually two part, First I have 4800 watts of solar on one charge controller strictly grid tied. The second part is 1480 watts solar on a 60A charge controller, tied to a 6048 inverter and the back up batteries, that portion is strictly off grid however it could also be grid tied and was at one point. The 6048 inverter is a 6000 watt continuous power/12,000 watt surge inverter, tied to a 48V battery bank.
The reason it is not grid tied is because of the extremely risky situation the world is now in. In case of an EMP (electro magnetic pulse) or any real issues with the grid, my equipment would be ruined, having it isolated, I'd still have my own power, up to the ability of the batteries and the inverter. If I was real certain that would happen, I'd have 400 AH batteries instead of 200AH, for more backup.
You also need to realize, 12V power needs heavier gauge wire than higher voltages. That's why the main cables on your car battery are so heavy, it's also why the grid transports power long distances at very high voltages, then transforms it to medium high voltages to go from sub stations, and again transformers to feed 240V/120V to your home. The extreme high voltages allow the pwer to flow with less loss than a lower voltage could do.
On 12V the wire must be heavy or the loss in voltage is lost as heat. Now, on your system even for a little 12V diaphragm pump, keep the 12V wiring heavy and short. It's far lower cost to move air (or vacuum) or sap in correctly sized piping than to use long wires for the distance.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.
Originally Posted by maple flats
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