It's not a good idea to run two dissimilar batteries in parallel, unless you=
use diode auctioneering. One tends to hog the load. When charging, one=
may draw too much current, gas, and use up its water. Even when not=
charging, one battery will charge the other and run itself down. Diode=
auctioneering lowers the voltage from the battery 0.7 volts which may cause=
problems in the UPS inverter control circuits, and to prevent one battery=
from charging the other, you would have to diode auctioneer the charger,=
which again, will sense voltage too high and cut off charging early. It's=
hard to get away from these problems even with matched batteries, because=
just a little difference between them caused by age, temperature, etc, will=
cause them to behave as dissimilar batteries. You could buy a higher=
capacity UPS. You know that a 500 watt inverter will deliver 500 watts for=
x minutes, but will deliver a lesser power for a longer period of time. =
Or you could go with the battery/charger/inverter. Here again, buy a big=
battery an don't try to run two smaller batteries in parallel.
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Be nice. It doesn't take any longer.
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Charles Greene
Internet=cejwvlhy@openrobots.net
Internet to Amprnet=nwe@edu.sg
115 Aaron Avenue
Bristol, RI (On the shore of beautiful Narragansett Bay)