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charging a 12V battery from a 48V dc source?

J

jim w

Jan 1, 1970
0
I need to get 12V from a 48V Solar (PV) system. The 48V is charged by 4
12Vdc PV panels, into eight 6V batteries.

I have a need for 12Vdc. I could just use a power supply on the AC side
of the inverter, but that seems like a waste of power
(48Vdc->inverter->transformer->regulated_PS).


Would it be reasonable to build a DC-DC drop-down switcher?
 
M

Madhu

Jan 1, 1970
0
A DC-DC converter is the way to go. ETA-USA (http://www.eta-usa.com/)
for one has a bunch of 48VDC input converter modules and using them is
simplicity itself. Likewise you can do a search of 48VDC input DC-DC
converters and come up with a lot of products that would match your
needs. I would not use the inverter-transformer method.
Madhu
 
S

SteveB

Jan 1, 1970
0
I don't suppose you could just take +12v direct from the 2nd battery up the
chain, a problem would be that the lower 2 batteries would get discharged
quicker than the top 4, so rotation would be needed to even things out.
 
C

ComTech

Jan 1, 1970
0
You're right a switcher would be the best way to go.

But there is a cheap and dirty way of doing things. You could put a power
resistor in series to your load. You would calculate the resistor by R = 36V
/ max current then calculate the wattage for the resistor. Again it is
really dirty and you should use zener and capacitor, but then I would try
the switcher.

Best of luck to you,

Comtech
 
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