----Original Message----- From: "Peri Hartman via EV" <ev@lists.evdl.org> > Hmm. Well, yes, there are two batteries in it but I can't tell the Ah. > I'll find out soon, when the power goes off :)
> You seem reasonably confident that the charger won't overload, it will > just take longer. My concern is that it might be designed to safely > charge at some current level just long enough to get the matching > batteries to float state. If I hook up something larger, then the high > current will persist a lot longer. Still safe ? As Lee mentioned in another reply, the built in charger is generally just a simply float. They won't deliver all that much charge, so I have never seen one overheat. Does not mean that it couldn't however. Check for heat... > As for the load, it seems that if it's rated for 900w, it should be safe > indefinitely at 100w. But who knows. Likely yes. > The model is BN1500M2, by APC (schnider). Sounds very similar to mine. I'll have to look when I get home. I have two 1500VA APC UPSes - one in the family room and one in the data cabinet. Both have been modified for external batteries. The one in the family room has about 50AH @ 24 volts and the data cabinet has 145AH @ 24 volts. Neither has seem more than an hour of run time because by that time, I have the generator running. Interesting timing on UPS discussions I had some excitement yesterday with the data cabinet UPS. From what I could piece together, a cell shorted in one of the two batteries about two weeks ago. The UPS charger tried to keep the voltage up. This resulted with a bunch of current pouring into the battery. I noticed it when the voltage monitor on the battery (not part of the UPS) started reporting voltage fluctuations overnight. When I checked Sunday morning, the first thing I noticed was the heat coming from the battery shelf at the bottom. One of the two batteries was too hot to touch, and the other was only a little cooler. Shut everything down and swapped out the UPS batteries. The UPS charger seems to have survived two weeks of heavy charging just fine. After everything cooled down, the battery that had been the hottest is floating about 2 volts lower than the other one, so pretty sure it has a shorted cell. To answer how I determined that the failure was two weeks ago, I have a temperature probe for the battery shelf on my environmental alarm for the data cabinet. It showed the battery shelf temperature rise substantially two weeks ago, but I had never set up alarm points for the battery shelf temperature. That oversight got fixed yesterday! 73 ----- Jim Walls - K6CCC j...@k6ccc.org _______________________________________________ Address messages to ev@lists.evdl.org No other addresses in TO and CC fields UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/ LIST INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org
