Battery vent holes

Gecko123 · 03-28-2026, 01:11 PM

I noticed my battery’s second vent hole is not plugged. The other hole is plugged to the vent tube

It’s been like this for 10 years and noticed it now when Time to change battery
It didn’t seem to damage anything but of course good idea to plug it

I’ve seen tons of battery replacement videos and none of them mention the importance of plugging this second hole.

Comments. Thoughts?

lordnikon · 03-28-2026, 01:25 PM

May be it'll cause uneven venting pressure but you're changing the batt anyway. Just make sure the vent hole on the other side is now sealed.

mainbearing · 03-28-2026, 08:40 PM

I always plug it with a new plug when replacing the battery. I do not want flammable hydrogen gas accumulating in the trunk. Or maybe acid fumes corroding things?

Sometimes the replacement plug on a card is missing from the new battery, if so remove the one from the old battery (if it still has the plug) and plug the new battery with it. I always made sure a new battery comes with a new plug.

Gecko123 · 03-29-2026, 06:35 AM

Thanks both. And interesting
video mainbearing

03-28-2026, 01:11 PM	#1
Gecko123 Private 41 Rep 93 Posts Drives: 2011 BMW 328xi Join Date: Feb 2016 Location: Canada iTrader: (0)	Battery vent holes I noticed my battery’s second vent hole is not plugged. The other hole is plugged to the vent tube It’s been like this for 10 years and noticed it now when Time to change battery It didn’t seem to damage anything but of course good idea to plug it I’ve seen tons of battery replacement videos and none of them mention the importance of plugging this second hole. Comments. Thoughts?
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03-28-2026, 01:25 PM	#2
lordnikon Captain 842 Rep 870 Posts Drives: Break My Wallet Join Date: Feb 2023 Location: 416 iTrader: (0) Garage List 2011 BMW 328i xDrive [0.00]	May be it'll cause uneven venting pressure but you're changing the batt anyway. Just make sure the vent hole on the other side is now sealed.
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03-28-2026, 08:40 PM	#3
mainbearing Colonel 1749 Rep 2,165 Posts Drives: BMW 328i Join Date: Apr 2019 Location: LA iTrader: (0)	I always plug it with a new plug when replacing the battery. I do not want flammable hydrogen gas accumulating in the trunk. Or maybe acid fumes corroding things? Sometimes the replacement plug on a card is missing from the new battery, if so remove the one from the old battery (if it still has the plug) and plug the new battery with it. I always made sure a new battery comes with a new plug. Last edited by mainbearing; 03-28-2026 at 08:45 PM..
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03-29-2026, 06:35 AM	#4
Gecko123 Private 41 Rep 93 Posts Drives: 2011 BMW 328xi Join Date: Feb 2016 Location: Canada iTrader: (0)	Thanks both. And interesting video mainbearing
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