The AGM battery on my 2016 Cayman has no vent either. They don't need vents, but it's possible that due to old regulations, batteries inside the vehicle could require one, even with AGMs. The only car I know of with battery inside the cabin is mid-engine Ferraris, but last one I checked was a 2006, with a factory wet-cell, and it did have a vent. Since 2008 they have AGMs, but haven't been in there (you need to remove the passenger foot kick-plate to access it). I don't think the frunk on our cars and trunk on Corvettes classify as 'inside the cabin', but who knows.

 

Thank you for the confirmation. I've been trying to understand AGM/not and vent tube/not. Searches brought out some contradictory information (as usual). Nice to hear from someone who actually knows, rather than from someone who just has an "opinion".

 

I thought that a feature of AGM was that the battery could be used in any orientation. Upside down, on end, etc. One of the earlier uses was boating - and they were advertised to work immersed in water (probably not a good long-term idea since water is a weak conductor).

So for the above reasons, a vent could allow a leak and/or contamination.

 

What was confusing me was that the AGM battery casing still has the same vent port openings near each terminal, albeit they are plugged up and unused. I suspect that the OEM battery supplier is using the identical battery casing for AGM or not, with different guts and the redundant holes blocked off.

 

AGM are sealed units, utilizing gel and fiberglass.

I would guess that the vent tube posts are just for holders of legacy vent tubes, to keep them in place. If you went back to a lead acid battery, you'd need them.

After a dozen AGM batteries on motorcycles and snowmobiles, I will use them on my Cayman when the time comes.

 

That's what I've heard. I love AGM, have an Odyssey AGM in the 914.


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