Is it ok to position SLA (sealed lead acid) / VRLA (valve-regulated lead acid) batteries upside down?

Are there safety, performance, or longevity implications?

Some UPS (uninterruptible power supply) units take multiple SLA/VRLA batteries, where some may be upside down. For example, the CyberPower CP1500PFCLCD takes two batteries with one right-side up, and another upside down:

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However, manufacturers of batteries state the battery can be positioned vertically or horizontally or sideways, but there is no mention of upside down:

With isolated seal, it is not limited to direction, position in place. It can be put in horizontal way, vertical way and side way, its safely and functions totally will not be affected.


Some vendors exclude upside down:

safe operation in any position except inverted


  • 1
    if the UPS is designed like this why not trust the UPS manufacturer?
    – user253751
    Feb 7, 2023 at 15:32
  • 1
    @user253751 trust but verify
    – adatum
    Feb 7, 2023 at 19:20
  • Seems like it's just bad design by CyberPower. APC's competing UPS units have the pair of batteries both oriented on their sides. Similar battery pack, but rotated by 90 degrees compared to the CyberPower unit's orientation of one upright and the other inverted.
    – adatum
    Feb 13, 2023 at 23:54

1 Answer 1


Safety considerations depend on the battery manufacturer's recommendation. Theoretically, they should work in any orientation. But only the manufacturers know how they have constructed the battery and whether they can be used upside down.

OR Novel Idea - just lay the UPS on its side.

I found this

“Unless it’s operating upside down, a VRLA battery should never leak acid,” says Wehmeyer. “That’s a huge advantage for applications where you might be in an office environment or a food storage application, where you don’t want any chance of acid spillage.”

From What To Know About Sealed Lead Acid Batteries

So that could be one reason for not inverting them.

  • 2
    Laying the UPS on its side works only until someone else goes "wtf is this" and "fixes" it. Don't do it. It's an accident waiting to happen.
    – gronostaj
    Feb 7, 2023 at 7:30
  • Orientation-wise, laying the UPS on its side works for the batteries, but it is awkward, takes up space, and also blocks some vents, so I don't think this is reasonable. As for the possibility of acid leaks, if that's the only issue, I suppose it can be risked since it's rare. Do the valves work properly upside down? Any other considerations? Very difficult to find concrete information.
    – adatum
    Feb 7, 2023 at 18:34

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