Car battery in a pressure vessel. - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: February 11, 2020, 02:37:24 am
content: Was thinking about VRLA batteries with their pressure release caps on each cell and got to wondering what would happen if you put a conventional car battery (stationary application) in a pressure vessel and pumped it up to say 100 psi or more. Would any gas that is liberated during charging be encouraged to be reabsorbed somehow, just like in a VRLA? Any other possible benefits?

author: ejeffrey
author_rank: Super Contributor
timestamp: February 11, 2020, 03:58:45 am
content: I don't think so. The point of sealing a lead acid battery isn't to increase the pressure it is just to keep the gases from diffusing away before the can be reacted back to water. If you put a vented battery in a pressure vessel any hydrogen produced is going to diffuse evenly throughout the vessel and get adsorbed extremely slowly if at all. Unless the vessel is extremely small in which case it is basically the same as a SLA.

author: Gregg
author_rank: Super Contributor
timestamp: February 11, 2020, 10:37:50 pm
content: Both Hydrogen and Oxygen can be released when charging lead acid batteries; you might end up with something like this if you try it in an enclosed space:https://youtu.be/l9CI6KSV560VRLA batteries are supposedly catalyzed to recombine the Hydrogen and Oxygen before they reach a dangerous level

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 11, 2020, 10:56:56 pm
content: I wonder how well the valves work on them, if they resist only modest pressures (hence venting any real pressure, in either direction), or if they act as check valves, in which case it would implode in the present example?Assuming it's fine, no, the impact on electrochemistry would be surprisingly small. AFAIK, pressures in the 100atm range are where that gets interesting.Better with a fine platinum catalyst, but still awkward. Not that there's an obvious way to combine lead or lead dioxide and platinum anyway, unless a simple mixture suffices?The standard definition hydrogen electrode reference, uses hydrogen, finely bubbled, at 1atm, over Pt gauze, in 1M [H+], IIRC. Understandable why AgCl:KCl and such are the preferred reference, and are simply calibrated against the standard.Tim

author: Stray Electron
author_rank: Super Contributor
timestamp: February 11, 2020, 11:39:29 pm
content: Would any gas that is liberated during charging be encouraged to be reabsorbed somehow, just like in a VRLA? Any other possible benefits?It's not a question of re-absorbing the gasses. When LA batteries are charged some of the H2O in them is broken down into hydrogen and oxygen and that's why water has to be added to a LA battery occasionally. No amount of pressure is going to recombine the hydrogen and oxygen into water. HOWEVER the newer sealed LA batteries contain other additives that helps prevent the breakdown of the water so they SEAL the batteries in anticipation that you will never have to add water to them. Carefully monitoring them (now fully automated) while charging also helps prevent water breakdown. People were bad about not checking their LA batteries and adding water when they needed it so sealing them didn't really give up much anyway.