Which unit is used to measure internal battery pressure?

And how can it be measured? (Does it change with battery age somehow?)

The internal battery pressure increases at high charging capacities and at high charging speeds, while a negative internal battery pressure occurs when the charging state goes towards zero, and discharging too quickly.

That's why batteries should be long-term-conserved at around 50% of charging level, to ensure minimum internal pressure.

  • \$\begingroup\$ Maybe bond (carefully) a strain gauge to the body or, if the battery has a vent use it to detect pressure build-up? \$\endgroup\$ – Andy aka Jul 19 '18 at 13:12
  • \$\begingroup\$ The international unit of pressure is the Pascal, Bar and PSI (pounds per square inch) are also used - do you really mean pressure as in force / area? \$\endgroup\$ – Solar Mike Jul 19 '18 at 13:12
  • \$\begingroup\$ Not denying what you say isn't true but I have yet to see a design example of pressure being used to determine battery charge state. How to measure: a pressure sensor? What else? Are you sure you're not confusing physical pressure with osmosis pressure (due to difference in ion concentration)? \$\endgroup\$ – Bimpelrekkie Jul 19 '18 at 13:12

I don't think this is correct unless you can point to a paper on it.

Pouch cells do swell as the SOC increases but this is mechanical and caused by the electrodes themselves swelling, it is not due to internal gas pressure.

I found this paper where they used neutron imaging to see this process happening. The change is tiny and not terribly linear though, pretty much every other method of measuring SOC would be better! They describe their 'dilatometer' measuring device in the paper.

Cells only become pressurised when abused and that's caused by vaporisation and/or decomposition of the electrolytes, vaporisation might be reversible when the cell cools (if the cell doesn't rupture) but decomposition is not.


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