SLA Battery Question  - Page 1
Forum section: electronics / beginners

author: threephase03
author_rank: Contributor
timestamp: January 22, 2022, 10:39:31 am
content: Hi Everyone.I have a 24V load that takes around 3.2A for approximately 25-30min then 0.5-1A for another 45min.The question is.... I want to buy two 12V SLA Batteries and run them in series what sort of issues couldI face with this type of application?I have a feeling there might be a discharge rate problemIssues with charging them back again and again. (Wouldn't be a daily use maybe twice a week)Link to what i want to buyhttps://www.jaycar.com.au/12v-9ah-sla-battery/p/SB2487?pos=9&queryId=aa8d8b3a70a7afd7c1a1e95ef57b547d&sort=relevanceThanks for any input/helpTIA

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 22, 2022, 10:41:24 am
content: If the units are identical, there's no problem.What do you think they do internally?(12V is 6 cells in series)Tim

author: threephase03
author_rank: Contributor
timestamp: January 22, 2022, 10:48:43 am
content: Im worried about the longevity of the application. I know it will work. But is it a to simple idea and im failing to see something?

author: BradC
author_rank: Super Contributor
timestamp: January 22, 2022, 10:53:53 am
content: It'll be fine, but don't expect those Jaycar batteries to last when you cycle them that hard.Something like a Vision FM or CSB GP series would likely last longer. The big trick to SLA longevity is charging them correctly.

author: threephase03
author_rank: Contributor
timestamp: January 22, 2022, 11:04:49 am
content: Thanks for the advice ill check them out. Much appreciated.I was thinking about using one of those car trickle chargers.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 22, 2022, 01:05:18 pm
content: And not over discharge; going under 50% is bad for lead acid.Tim

author: BrokenYugo
author_rank: Super Contributor
timestamp: January 22, 2022, 08:40:55 pm
content: Balance/equalization charges are just part of life with lead acid.

author: threephase03
author_rank: Contributor
timestamp: January 22, 2022, 10:12:38 pm
content: Thanks for everyone's input. I've got a 24V battery charge indicator, thinking about installing it on the battery box so I can check during use.Guess I'm hoping when it indicates its close to flat it isn't below the 50% min level mentioned

author: Circlotron
author_rank: Super Contributor
timestamp: January 22, 2022, 10:33:24 pm
content: You could always charge them with two independent 12V chargers at the same time. 13.65V @ 20 deg C. More readily available than 24V chargers and less likelihood of cell voltage imbalance because of a shorter string of cells.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 23, 2022, 01:49:18 am
content: Might want to consider 6S lithium ion instead, similar cost to sealed lead acid (particularly for small packs) but lasts a lot longer.

author: threephase03
author_rank: Contributor
timestamp: January 23, 2022, 02:38:27 am
content: Yeah thats what I was thinking, I already have one for my car as it sits there a bit now with all the stuff happening now days

author: SmallCog
author_rank: Frequent Contributor
timestamp: January 23, 2022, 11:57:35 am
content: One of the instruments we use draws 16A for 3 seconds once an hour. Power is provided by a 7AHr lead acid battery and we find 3 years to be a safe service life.As above no issues with series batteries, but if they don’t age the same one will die first. When ones dies you’ll have to replace both*not using random jaycar batteries so can’t speak for their reliability but we find the century batteries from BSA to be exceptionally good.

author: threephase03
author_rank: Contributor
timestamp: January 26, 2022, 03:45:05 am
content: If I could get 10 - 15 charges out of them they will make their money back.So ill think it will be rightThanks for everyone's help

author: tkamiya
author_rank: Super Contributor
timestamp: January 28, 2022, 07:17:35 pm
content: Why not buy a 24V SLA? They are not as common but they do exist.