Compatibility of 12V lead acid batteries for UPS - Page 1
Forum section: electronics / general

author: petemate
author_rank: Regular Contributor
timestamp: September 30, 2025, 06:16:14 pm
content: I'm looking to replace the batteries in my UPS, as one of them has gone bad. But I don't know which parameters to compare when looking at alternatives. The manufacturer says to replace with only their own type of battery, but oddly enough a different type of battery was installed in the UPS.I have now found a third type of battery that I would like to install, mostly because they are cheaper - but also because they claim a longer shelf life. What parameters should I compare to determine if the batteries are compatible - apart from voltage and ampere-hours, ofcourse?Original manufacturer battery:https://files.plytix.com/api/v1.1/file/public_files/pim/assets/18/55/4e/5e/5e4e551814d5697e060409a6/texts/41/ca/5f/62/625fca41f35177c342dddc9b/PowerWalker%20PWB12-9.pdfBattery mounted in UPS:https://www.baterije.org/specifikacijebaterija/MS9-12.pdfPossible third battery option:https://dealers.lakuda.de/media/blfa_file/JAPCELL_JCL12-9.pdfI have a gut feeling that all 12V lead-acid batteries are essentially compatible, but each battery lists something slightly different for "float" and "cycle" use. Are those parameters just recommendations for voltage range in the different use cases, or whats going on?

author: kite31
author_rank: Regular Contributor
timestamp: September 30, 2025, 09:56:44 pm
content: Depending on reliability of power in your area, the battery will spend practically all, if not all, its time floating for the next 3-5 years. Given the type of battery you are discussing your UPS is not a large commercial one so there is little point chasing cycle or depth of discharge performance. Buy something not terrible at reasonable cost. The manufacturer's preferred product will be nothing special.

author: petemate
author_rank: Regular Contributor
timestamp: October 01, 2025, 07:19:46 pm
content: Thanks for your reply. I take the "just buy something not terrible" to mean that there isn't any real compatibility issues with the batteries?

author: thm_w
author_rank: Super Contributor
timestamp: October 01, 2025, 11:17:17 pm
content: Yes, all of those are designed for UPS use so will be fine.If you want it to last longer you can also consider replacing with a Lifepo4 battery.

author: kite31
author_rank: Regular Contributor
timestamp: October 01, 2025, 11:21:11 pm
content: None of which I am aware. My UPS and NBN box have had a variety of battery brands used as replacements with little regard for what was in there before.

author: David Hess
author_rank: Super Contributor
timestamp: October 01, 2025, 11:50:37 pm
content: That 12 volt 9 amp-hour battery is a standard format with many sources. I would not worry about an exact match for something which was probably not specified that closely.

author: JimboJack
author_rank: Regular Contributor
timestamp: October 02, 2025, 05:24:48 am
content: the discharge current on a SLA is alot higher than a LifePo4 battery, about x10 times.I would not go near a Lifepo4 for a UPS battery replacement when it specified SLA's or wet cells20Ah Lifepo4 battery is in the 20Amps20Ah SLA or lead acid is in 100A's range.same with smaller units of LifePo4 9Ah is about 10Amp tops. -> 120W about max ideal conditionsso to get the same discharge rate you going to need at least a 100Ah LifePo4 which defeats the point of a small 9Ah SLAit one of reasons UPS's have gone to higher battery voltage requirements, not using large transformers as well.

author: petemate
author_rank: Regular Contributor
timestamp: October 02, 2025, 10:35:52 pm
content: Thanks for your inputs!