I recently had to replace a battery pack on APC Back-UPS 1500, since it stopped charging after 3 years of service close to a heat source, and upon inspection one battery get cracked and swelled on one side. I got a brand new APC battery pack, reset the battery date in PowerChute, then Brain Dead the UPS, fully discharged and charged the new pack a couple of times to reset the microchip and train the battery. Measured voltage on the pack, it was 30.8V charged.
Two days later there was heard a pop after a relay kick and 2 beeps every two seconds started. Back-UPS was showing various errors at each reset, like F05 bad charger, next time F06 relay weld, etc. I took out the pack, and suddenly its voltage dropped to 12.6V, i.e 6.3V per battery as measured. The UPS was still showing full charge. During these 2 days no load was attached to the battery outlets, only a small load to Surge Protection outlets, and there was no surge in mains that I noticed.
I put another good battery pack into the UPS, and it restarted seemingly normal operation with all tests passed, and discharge & charge cycle under a test load 30%. I disassembled the fully discharged pack, and put its batteries to another UPS, so they're slowly charging, at 12V now after 6 hours. It seems everything works as it should: the UPS works again with another pack, and the discharged batteries are being charged again and pass the start test in another UPS.
My Q is: what happen? Why fully charged new batteries get fully discharged below limit in 2 days, while no load was attached to them? If they're short, why they recharged again in a different UPS? May be the UPS caused a short to batteries, or some component gives intermittent fault? What should I do now?
Another Q: can 2 batteries at different discharge level be charged together by the UPS as a pack? Like one is at 14V, and another at 6V, but surprisingly keeps charging? How in this case the charge levels between batteries, and how the UPS decides that the pack get fully charged? How generally the UPS measures a battery charge level?
More Q: can I use together a 3-year old good battery and a brand new one as a pack? If not recommended - why?
Two days later there was heard a pop after a relay kick and 2 beeps every two seconds started. Back-UPS was showing various errors at each reset, like F05 bad charger, next time F06 relay weld, etc. I took out the pack, and suddenly its voltage dropped to 12.6V, i.e 6.3V per battery as measured. The UPS was still showing full charge. During these 2 days no load was attached to the battery outlets, only a small load to Surge Protection outlets, and there was no surge in mains that I noticed.
I put another good battery pack into the UPS, and it restarted seemingly normal operation with all tests passed, and discharge & charge cycle under a test load 30%. I disassembled the fully discharged pack, and put its batteries to another UPS, so they're slowly charging, at 12V now after 6 hours. It seems everything works as it should: the UPS works again with another pack, and the discharged batteries are being charged again and pass the start test in another UPS.
My Q is: what happen? Why fully charged new batteries get fully discharged below limit in 2 days, while no load was attached to them? If they're short, why they recharged again in a different UPS? May be the UPS caused a short to batteries, or some component gives intermittent fault? What should I do now?
Another Q: can 2 batteries at different discharge level be charged together by the UPS as a pack? Like one is at 14V, and another at 6V, but surprisingly keeps charging? How in this case the charge levels between batteries, and how the UPS decides that the pack get fully charged? How generally the UPS measures a battery charge level?
More Q: can I use together a 3-year old good battery and a brand new one as a pack? If not recommended - why?
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