On 06 Dec 96 at 21:32, Roy J. Tellason of 1:270/615
wrote to Chris Harper about :
 RJT> What will you consider "discharged"?  I've seen
 RJT> specs for that going to,  say,  10.5 volts for a 12 volt battery,  
though
 RJT> I wouldn't want to make it a habit to run them down that far.  Voltage
 RJT> can also be misleading if you're dealing with surface charge at all.
The point I will call discharged, is the point in which my inverter will no 
longer produce at least 110VAC, given the batteries' input. I would think 
that would be determined by the voltage of the batteries. Am I mistaken?
I was considering trying to find a less than 3 volt battery I could switch 
into the battery (series connect) when voltages get low in order to drain the 
other batteries further, if it's beneficial to. If it's not, then I can save 
the trouble and cost of the low voltage battery setup.
BTW - do you know the average "usable capacity" (of an average cycle) of an 
average 12 volt deep cycle battery I can obtain easily? I need to estimate 
how many batteries I would need to have 200-300 KW available (total, not per 
hour;-) to be used at around 1.5-3KW/Hour. This should give me around five 
days storage capacity, I believe. That is, If I could pull 10KW from a 
battery before it no longer will run the inverter, I would need 20-30 
batteries. But I have no idea how much wattage I can drain from an average 
deep cycle battery.
I doubt any single average deep cycle battery could deliver 3KWH for any 
length of time without suffering increased wear, and I intend to hook several 
in parallel to reduce the load on any single battery. I may have that pack 
run into a couple common car batteries, which will handle surge needs, and be 
replenished by the deep cycle pack.
The car batteries would handle not only surge demends, but would take the 
main charge from the panels, as the charge would vary with clouds passing and 
such. The car batteries would act similar to an extremely large capacitor, in 
effect, to smooth out the load (either inbound or outbound) for the deep 
cycle batteries, which would handle the main storage.
Could I just connect them all in parallel to accomplish this, or would I need 
to use a special circut to prevent the deep cycles from handling surges?
I was thinking that I could hook it up like this:
+++++..++L+
DDDDD  CC
-----..--L-
Where "D" is the deep cycle batteries, "C" is the car batteries, "L" is the 
load or charge, and "." is either cable or special circut (if needed). As the 
load or charge would hit the car batteries first, I am hoping they'd buffer 
the deep cycles.
What do you think?
TIA,
       Chris Harper
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