Should I even keep these lead-acid batteries? - Page 1
Forum section: electronics / general

author: Amish_Fighter_Pilot
author_rank: Regular Contributor
timestamp: June 01, 2025, 12:44:09 am
content: I have maybe 200-300 batteries from medical equipment that was retired. Most of them work, but I am increasingly unsure I should even bother with these things.[ Specified attachment is not available ]I have an inverter on my home, but we basically never use it. I am also not sure enough of these are in matching condition to put in a battery bank. I could test and sort them extensively, but I am not sure it's worth it. Most of what I do requiring batteries is very remote and I don't want to lug around hundreds of pounds of batteries with me in the mountains or the desert...Should I just take these to the scrap yard and buy some LiFePo4 units instead?

author: wilfred
author_rank: Super Contributor
timestamp: June 01, 2025, 01:36:57 am
content: If medical equipment is regularly tested and the batteries are still good because you know, medical equipment, then I would try to sell them. Even if it save you going to the effort of scrapping them. That'll always be your fallback option for those no-one wants.-I have driveway gates that use those types of batteries in the event of a power failure. There must be a use for them if they still hold a charge. Older car jump-starters like one I had was a 19Ah SLA battery.Yes, get rid of them since you don't need them and don't want to bother with the obvious application. Even if you sold the lot for twice the scrap value you'd be ahead because you didn't have to load and transport them to the scrapyard.

author: Freesurfer
author_rank: Regular Contributor
timestamp: June 03, 2025, 11:21:59 pm
content: I have dealt a fair bit with used lead acid batteries. They don't have infinite shelf life so it depends a lot on the age.In the best case, some can last for 10-12 years under ideal conditions, which pretty much means sitting 100% charged on a float charger with the correct voltage for the battery, at 20-25C (68-77F) without being cycled very often. Not impossible if the batteries have been in a UPS in a temperature controlled room with few power cuts. But for any other condition it will derate the life expectancy of the batteries, especially from higher temperatures. So 6-8 years is more realistic.Another challenge is batteries with uneven wear if they aren't from the same system/location. In my experience, mixing good and bad batteries generally only gives the disadvantages of the bad battery, and none of the advantages of the good one.Even if the batteries have some usable capacity, also consider the time and cost of the cabling needed to set the batteries up, and how often you want to do the re-wiring work, and how much wiring you will need if the batteries are small.That said I have had success with used batteries before. What I do is I fully charge the batteries and then use a cheap battery tester that I have (MICRO 200 pro) which measures the battery's ESR and gives a guesstimated capacity. If the batteries' ESR is good and consistent between batteries, I pair up the good ones with similar values. The ESR is a good indication of the condition of the batteries, even if it may not show the full picture.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 03, 2025, 11:51:33 pm
content: A lot depends on what you mean by retired. In equipment that needs to work, and medical equipment is certainly in that category, the batteries are often replaced by age. Well before the expected lifetime so that there is little or no chance of failure. If that is the source of these batteries and their removal date was recent they likely have a lot of life left and are well worth keeping.But these AGM batteries don't recover well if they are ever allowed to discharge down to well below operating voltage. Self discharge does that if they have been sitting on the shelf for a couple of years. They also have minimum excess electrolyte and degrade rapidly on overcharge. If any of these conditions apply I wouldn't bother doing anything more than sending them to the recycler.