Re: APC Smart-UPS float voltage experiment

It's been five years since I replaced the batteries and they finally failed their periodic test. So, I'm calling the experiment a success. I replaced them again with some cheap batteries from ebay. However, I've become persuaded that a 3.3 megaohm resistor might be better than the 2.2 megaohm resistor that I used the last time. I've modified another ups with that resistor and I get a float voltage of about 27.2. We'll see how that goes. In addition, I used apcfix to restore the battery constant. I did try to adjust the float voltage with...

Re: APC Smart-UPS float voltage experiment

I've been testing this further and have more data. This is with a different UPS and rather weak batteries. These are the batteries that I replaced because the server UPS was running with its fan on all the time. However, there doesn't seem to be a dead cell, which is a common way for these to fail in my experience. So, what I did was test various add on resistor values. I let the system fully charge the batteries. Then I took multimeter readings on the connections going to the battery and collected data from apctest, which is a program...

Re: APC Smart-UPS float voltage experiment

Actually, mine never fail that test. I find out the battery is bad because the fan starts running all the time. Usually by then, one of the battery posts is sulfating too. I'm always worried that something's going to drip and mess things up. Fortunately, that hasn't happened yet.

Re: APC Smart-UPS float voltage experiment

That link was interesting. I could certainly believe that I've gone a little far with this. The thing about sulfation on the negative plate was interesting. Maybe a better float voltage would be that 26.5 or 27 if you wanted to tweak with a couple of resistors. Maybe I'll put the 1.5 megaohm back in. But my current 25.6 volts is higher than the 2.10 volts per cell they mentioned for sulfation. For me, this isn't an especially expensive experiment. The batteries were $66 and I have about ten UPSes. I haven't bothered to count them and I...

Re: APC Smart-UPS float voltage experiment

Actually, I did look at the schematic to verify that the idea looked consistent before I embarked on this adventure.

I have several APC Smart-UPS 1400 UPSes. I've never gotten the battery life that I thought that I should, but I don't buy expensive batteries either. I just get them on Ebay. I've read several times that APC UPSes over charge the batteries and my experience seems consistent with that. Usually at some point the fan starts running all the time and one of the posts starts sulfating. Indeed, I got these UPSes from a company that was throwing them out because one almost started a fire. These were all made around 1998. So I was getting tired of buying batteries every two years, so I did some research...