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Source for 12 V, 7 Ah SLA casings for DIY
#1
So the batteries in my UPS died, again, and prices for new SLA batteries was in the $70 range. A DIY project will probably cost me more, even with free 18650 cells on hand, but I don't like that the SLAs keep failing after four years despite only one cycle and a very resonable float voltage.

These boxes for DIYing a replacement battery does show up on image search, but does anyone here have any expereince with where to buy them and if it's worth the hassle?

Cells tested: 4087
Average capacity: 2082 mAh
Left to process: 165 kg
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#2
Never used it, don't know this seller, but here it is:
https://www.aliexpress.com/item/4000430838449.html
winny likes this post
Modular PowerShelf using 3D printed packs.  60kWh and growing.
https://secondlifestorage.com/showthread.php?tid=6458
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#3
(09-21-2020, 10:36 AM)ajw22 Wrote: Never used it, don't know this seller, but here it is:
https://www.aliexpress.com/item/4000430838449.html

Thanks! Seems more suitable for a 7S 24 V. I'll investigate :-)
ajw22 likes this post
Cells tested: 4087
Average capacity: 2082 mAh
Left to process: 165 kg
Reply
#4
If you must go with 12v - then 18650 just won't work well (wrong voltage range) - maybe you could find some LifePo4 cells and do 4s?.    If you can step up to 24v APC then 18650 based battery (7s) will work great.    In either case you don't need to buy a special case (see that pun? Smile ).  You can build a battery (tape it together is OK) with a small bms and spade connectors for + and -
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#5
(09-21-2020, 03:38 PM)OffGridInTheCity Wrote: If you must go with 12v - then 18650 just won't work well (wrong voltage range) - maybe you could find some LifePo4 cells and do 4s?.    If you can step up to 24v APC then 18650 based battery (7s) will work great.    In either case you don't need to buy a special case (see that pun? Smile ).  You can build a battery (tape it together is OK) with a small bms and spade connectors for + and -

It's two 12 V 7 Ah SLAs in series. Bog standard in small UPSes.
It would be more flexible with 12 V replacements, but with a maximum of 21 cells, it's no good match which can handle say 13.7 V. 24 V will be less flexible but a good fit for this UPS in particular if I just parallel them. Ditching the form factor all together and using up all the space available from the two batteries is an option too.

I'm yet to invest in a spot welder so I was hoping there was some simple solderless DIY kit for the purpose since more people than me should have noticed the shortcommings of SLAs in UPSes and the abundancy of 18650 cells.
Cells tested: 4087
Average capacity: 2082 mAh
Left to process: 165 kg
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