Henty

Thanks for the info Arandozo You've convinced me (I was 80% convinced before you answered) that it's not going to be worth the effort of keeping this old-tech UPS going and spending yet more money on new batteries. I should just bite the bullet and go with Lithium. Was hoping to eek out another year from the current batteries somehow. To answer your questions: The more recent set of batteries (CSB HR 1234W) are AGM. The previous set (CSB GP 1272) seem to be AGM too, although I didn't realise that until googling a few minutes ago. The DOD of the UPS is not configurable or listed but it seems to shut off at 230V, which is below 50% based on the tables I've seen. With the fairly low load I don't think I ever got close to this in the first year though, before the battery capacity started falling (so maybe I somehow did get close in the first year, else why did it fall?) after which I must have hit it frequently. That explains why they've degraded so rapidly in the last few months. There is no BMS and having checked individual batteries in each string with a multi-meter, their voltage is not 100% consistent, but didn't seem crazily bad to my layman standards. Once discharged they were almost all between 12.9V and 13.1V. I removed the few that were below 12.9 by reducing from 4 strings (of mixed batteries) to 3 strings (of only stronger batteries), but it didn't make much difference.

I have a Q-on 6KS 6kVA UPS with an extended battery pack that I'm using to power some computer/screen/tv devices and LED lights during load shedding. The make is also sold under the brands Socomec, Eaton, Certa (and probably many more). It works well on brand new batteries for the first year or so, but after approx 18 months of light use the batteries seem to have degraded severely. It's happened with 2 sets of batteries (the second set replacing the first). I'm trying to figure out how to: - prevent this fast degradation - I was expecting the batteries to last at least 3 years - revive the batteries if it's at all possible. First set of batteries: 4 strings of 20x12V CSB 1272 28W (7.2Ah) = total 240V, 80x12x7.2 = 6.9kWh replaced by Second set of batteries: 4 strings of 20x12V CSB HR 1234W 34W (9Ah) = total 240V, 80x12x9 = 8.6kWh Runs: in "High Efficiency / Economy" mode, 230V, 50Hz output. Extended battery pack has its own charger. Typical load is around 500W, it never goes above 1kW when in battery mode. At the start of the 18 months, as a once-off test, the UPS could easily manage 4h at constant(ish) 500W load without the voltage dropping close to 230V. At the end of the 18 nonths it didn't even last 30min. What's possibly odd is that the voltage seems to be dropping slowly for a while and then suddenly drops off very quickly even though the load is fairly constant (around 7% of max) and low. See attached pics. Individual batteries currently measure: 13.85V when in the UPS and fully charged (taking UPS reported 277V/20) 13.2V when left for 4 days after being fully charged (charged w. separate smart charger and left) 12.9V to 13.1V after the UPS switches off (20 x 13V = 260V) It's that last measurement that seems odd since the UPS reports <230V when it shuts down. So the batteries seem to "bounce back" I tried removing any batteries that were below 12.9V (worst was 12.5V) after shutdown and using good batteries in 3 strings instead of a mix of good and weaker batteries in 4 strings. Unfortunately the performance was even worse. Any advice on what might be going wrong (if anything) and if there's any chance in reviving the (rather expensive) 80 batteries would be very much appreciated.