Sealed Batteries vs. Unsealed Batteries

[apchemstudent]

Newly devised automobile batteries are sealed. When lead storage batteries discharge, they produce hydrogen. Do you know why sealed lead storage batteries have not been used in the past?

Is it because the hydrogen gas is hazardous under such high pressure and back then, they couldn't sustain a safe temperature for the batteries since no such technology was available yet or well-equipped for that job?

I had to estimate the increase in pressure if 0.05 grams of hydrogen gas was produced and it was around 6 atm.

Please reply. If you don't agree, please explain your answer as well, thanks in advance.

 

[anorlunda]

Sealed batteries have a safety vent to allow gas to escape if pressure gets too high. So the answer is, that the pressure does increase to whatever value the safety vent is set for.

But when charge is complete, pressurized hydrogen is reabsorbed, so the gas pressure is not cumulative over the life of the battery.