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Power system thoughts?

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Flag:
Many systems (especially Davis) are 5-6 volts yet most solar systems and especially most solar regulators are 12 volt.

So what are the preferred options?

1) 12V system / 12 volt battery and DC/DC convertors to 5-6 volts
2) 12V system / 6 volt paired batteries with 6 volt feeds direct from 6 volt battery

The main issue I see are systems with no Low Voltage Disconnect (LVD) which have the possibility of completely stuffing the battery during times of malfunction or lack of sunlight.     

Does anybody know of a solar manufacturer that makes a 6 volt regulator? 

DanS:
At the output of the 12 volt solar regulator pop one of these in to regulate down to +6 volts (or a 7805 for +5 volts). Current handling is sufficient. Or you could use a LM317 (adj. version) if you need another voltage (lower than 12v).



You would have to build a little circuit similar to this on a matchbook size board.



Common Radio Shack type parts too.

johnd:

--- Quote from: Flag on March 16, 2011, 04:26:29 AM ---So what are the preferred options?

1) 12V system / 12 volt battery and DC/DC convertors to 5-6 volts
2) 12V system / 6 volt paired batteries with 6 volt feeds direct from 6 volt battery
--- End quote ---
Either is viable but personally I prefer [1] because it's a lot simpler to add a DC/DC converter into a 12v solar PSU than install a separate 6v solar PSU.


--- Quote ---The main issue I see are systems with no Low Voltage Disconnect (LVD) which have the possibility of completely stuffing the battery during times of malfunction or lack of sunlight.
--- End quote ---
It's not difficult to install your own LVD. Actually I've built a little box that has two separate LVDs, one for the 12v supply and one for the 5v supply. The idea is that the 12v one which powers a cellular modem and is the power hog cuts out before the 5v one and allows the logger to keep logging even if the cellular data link is allowed to drop out. Apart from anything else I prefer the ability to define my own LVD voltage levels and not rely on the often vague specs that the regulator makers provide. There's also often too much hysteresis built into the regulator settings IMO.

If you want to email me (support<at>prodata.co.uk) I can let you know at least one source for a reasonably cheap 12v LVD board.


--- Quote ---Does anybody know of a solar manufacturer that makes a 6 volt regulator? 
--- End quote ---
I do remember seeing some when I was looking around previously, so they do exist, but can't remember any details right now.

DanS:
You can cut out all the conversion stuff if you don't need 12v - http://www.google.com/products/catalog?q=6+volt+solar+panel&hl=en&um=1&ie=UTF-8&cid=7218398043270871512&sa=X&ei=iaCATZOeOM_NrQf3zMGmBw&ved=0CGoQ8wIwADgU#  but of course you'll get longer run times using 12v equipment.

Flag:
6 volt panels are not generally the problem, it's the 6 volt solar regulators that aren't all that common

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