On Monday 08 June 2015 14:28:30 [email protected] wrote: > I have a ups that has failing batteries. It is a good ups with an > external battery connector. I would like to pull out the SLA batteries > and hook up 2 deep cycle batteries to the external port. Will the ups > keep these deep cycle batteries charged? Will it ruin them? I plan to > move the unit outside to the porch and run a line inside.
There is a small but important differential between the float voltage of a good SLA, and the float voltage of the more or less std LA battery. I did this for a couple years back just barely post jurrasic with an NCR standby that originally came with SLA's and floated the whole string at 54 volts. But 54 volts had the regular batteries boiling over into a baby food jar full of soda in just a few hours. Working w/o any docs as it was from a dumpster dive, I found the float voltage pot and turned it down to 51 volts, splitting the diff between the nominally 48 volt string of SLA's. That did slow down the overcharge and gassing rate, but that set of yard machine betteries was history and burned dry in 6 months anyway, so when I put the next 100 dollar bill worth of batteries in it, I set it down to 49.5 volts. In 9 months, that set of batteries were history too, as was the jar full of soda. At that point I bought a 1500WA SLA battery'd unit, and got about 3.5 years out of its batteries 3 times in a row. I now have an identical rated device that only uses 3 batteries, which is on its 2nd set of batteries after 8 years or so. The UPS folks are apparently learning about the care and feeding of SLA batteries & getting more life with each new generation of UPS's they peddle. Or the batteries themselves are improving. So this is a case of a newer unit standing an excellent chance of being a better, longer lasting unit. The care and feeding of Lead Acid batteries is a science all by itself. Many years ago, I was responsible for a standby generator whose batteries to start it were nearly done, not enough left to spin that 335 Cummins. The standing voltage, trickle charger was a 10 amp charger with a 100 ohm current limiter, which explained why I couldn't keep water in them in the first place. So I went to town and got 2 more of those 120lb+ truck batteries and set them into the rack. With those batteries that Cummins fired and was running on the first cylinder to go by TDC. I hooked up the charger and they were boiling vigorously in 10 minutes. I doubled the resistor to reduce the charge, checking every hour for gassing and if they were gassing, doubled the resistor again. I finally quit playing with it a couple days later when the resistor was a 47k with the actual trickle current about 10 milliamps. 8 years later, when another job with more sheckles and a title came with it had my name on it, those batteries were still turning that Cummins 335 wrong side out starting it. Amazing, you hear the solenoid bendix kick in, and before you could hear the starter itself, it was running under its own power. Bottom line is if you see that battery gassing, you are overcharging it. I don't believe I used a whole gallon of distilled water keeping those batteries at the full mark in that 8 years. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
