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Post by mediadogg on Nov 17, 2019 14:40:58 GMT
I have been considering using a charge controller as a "poor man's" DC to DC charger. Since the newest cheap PWM CCs from Renogy can charge every type of battery. Reading about this on the net reveals (as usual) lots of controversy as to whether it is better to use an MPPT or PWM CC for such a purpose. However, most all agree that using a well-regulated "stiff" power supply as input to the CC (via PV terminals) is not as good as using a mushy power supply, so that the input to the CC roughly simulates a PV whose voltage and current can be regulated by the CC.
What I specifically want to try is connecting a 12 - 24V DC supply (e.g. a battery) to the PV input terminals of a Renogy PWM CC as a cheap but safe alternative to a Li-iron charger. The DC input to the CC would be connected in series with a suitably selected ballast such as a small DC light bulb, to give some springiness to the input for CC to apply current regulation.
Any thoughts? ("hey man, you are definitely looney tunes" - heard it before)
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Post by Aevolet Gravesd on Jan 7, 2020 19:25:57 GMT
Hello,
We have extend this offer for you to provide us with a price quote for the item listed below:
40A MPPT charge controller------------86 pieces
Looking forward to doing business with your company
Thank you.
Sincerely yours,
Aevolet Gravesd
President, Student Affairs
CITY COLLEGES OF CHICAGO
180 N. Wabash
Chicago, IL 60601
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Post by Guest on Jan 7, 2020 22:48:06 GMT
That is an interesting idea. I had never thought to use a solar charge controller to charge a battery with an unregulated power supply.
You could also charge a 12 volt battery with a 24 volt, or two 12 volt batteries in series...
That brings up some other ideas... If you have a 24 volt battery system (two 12 volt batteries in series), but need to power something fairly light 12 volt load off of it, connect a separate charge controller so the input is connected to the two 12 volt batteries in series, the connect the output to a small 12 volt battery to supply power at 12 volts. If you have extra small charge controllers and possibly small 12 volt batteries laying around, you may not need to buy anything.
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Post by Admin on Jan 7, 2020 22:49:40 GMT
I have been considering using a charge controller as a "poor man's" DC to DC charger. Since the newest cheap PWM CCs from Renogy can charge every type of battery. Reading about this on the net reveals (as usual) lots of controversy as to whether it is better to use an MPPT or PWM CC for such a purpose. However, most all agree that using a well-regulated "stiff" power supply as input to the CC (via PV terminals) is not as good as using a mushy power supply, so that the input to the CC roughly simulates a PV whose voltage and current can be regulated by the CC. What I specifically want to try is connecting a 12 - 24V DC supply (e.g. a battery) to the PV input terminals of a Renogy PWM CC as a cheap but safe alternative to a Li-iron charger. The DC input to the CC would be connected in series with a suitably selected ballast such as a small DC light bulb, to give some springiness to the input for CC to apply current regulation. Any thoughts? ("hey man, you are definitely looney tunes" - heard it before) Connecting a 12 - 24V battery to the PV input terminals of a PWM controller would damage the PV terminals and the controller, the PWM controller is not designed to be connected that way. -Renogy Team |
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russ
Solar Advocate
Posts: 63
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Post by russ on Jan 8, 2020 6:26:10 GMT
I have been considering using a charge controller as a "poor man's" DC to DC charger. Since the newest cheap PWM CCs from Renogy can charge every type of battery. Reading about this on the net reveals (as usual) lots of controversy as to whether it is better to use an MPPT or PWM CC for such a purpose. However, most all agree that using a well-regulated "stiff" power supply as input to the CC (via PV terminals) is not as good as using a mushy power supply, so that the input to the CC roughly simulates a PV whose voltage and current can be regulated by the CC. What I specifically want to try is connecting a 12 - 24V DC supply (e.g. a battery) to the PV input terminals of a Renogy PWM CC as a cheap but safe alternative to a Li-iron charger. The DC input to the CC would be connected in series with a suitably selected ballast such as a small DC light bulb, to give some springiness to the input for CC to apply current regulation. Any thoughts? ("hey man, you are definitely looney tunes" - heard it before) Connecting a 12 - 24V battery to the PV input terminals of a PWM controller would damage the PV terminals and the controller, the PWM controller is not designed to be connected that way. -Renogy Team Using a battery source connected to a PWM charge controller input without current limiting could cause the charge controller to supply more current to the output than it can handle. The charge controller input is normally limited by the maximum output current of the solar panels. A battery, typically, can supply much more current. |
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Post by mediadogg on Jan 9, 2020 14:23:16 GMT
Seeing the last two posts late. But yes, it makes sense. What was I thinking ...
Although my idea did include a "solution" for current limiting. I actually did consider that.
"The DC input to the CC would be connected in series with a suitably selected ballast such as a small DC light bulb, to give some springiness to the input for CC to apply current regulation."
All that being said: ain't gonna do it.
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Post by Tim Steinkamp on Feb 17, 2020 8:32:27 GMT
I am confused. Where does the excess power go from a solar panel when the battery is full? Is it heat dissipated by the controller? Does a solar panel push power like a battery pushes power? I understand in wind and hydro you need a place to put the excess power or else you burn up the generator or the turbine and in wind it goes out of control but a solar panel is passive like a battery, right? I need a professor.
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Post by Tim Steinkamp on Feb 17, 2020 8:56:37 GMT
Thinking of this how does an alternator dispose of the power it is generating when the battery is full because it is still spinning. A solar panel will take the power from the battery at night when it gets dark and the voltage drops one volt below the battery voltage unless you put in a diode. If you have a solar panel hooked to a battery it will boil it dry unless you have a controller to stop the flow into it and the power is wasted somewhere, but if the power is in a battery then why would it not work? To do an equalization you need a good 16 volts which is not much more than a 24 volt battery.
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Post by bupkis on Feb 17, 2020 12:30:38 GMT
mediadogg, for your amusement www.youtube.com/watch?v=36AfkZeXxIUTim Steinkamp, the controller stops the panel from making power when it is not needed, with an open circuit the panel makes zero power. |
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Post by mediadogg on Feb 17, 2020 23:11:29 GMT
mediadogg, for your amusement www.youtube.com/watch?v=36AfkZeXxIUTim Steinkamp, the controller stops the panel from making power when it is not needed, with an open circuit the panel makes zero power. Hey now! Nice one. So, I guess I'm not totally looney tunes after all! Thanks so much for that.  |
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