Once again, may I air my total ignorance of most things, in public? What on earth is an overboard discharge? Ah! It wouldn’t be anything to do with that little vent pipe on the battery, by any chance...?

 

yes, it is the little vent pipe on the battery that connects to the rubber tube exiting in a rubber grommet in the floor. if you have someone wiggle it, you can see it by the right wheel well. check the other end of the battery. often there is another vent hole. usually new batteries have a small parts kit with a plug and some fittings for the overboard discharge. mechanics often throw this kit away when installing a battery and forget to plug the other hole.

i have seen a trunk (boot) lid blow open from a battery explosion. once was enough.

 

Wow! A zip carry case for the Golf. Not fair, Mike! I want one for my XKR

 

no vent on my AGM battery.

PS. that said, any AGM battery will vent externally under continuous overcharging. No battery should be put in tightly sealed compartment. Doing so is asking for trouble.

But the battery bin in the X-100’s could hardly be called tightly sealed..


there are zip up cocoons for cars, but no carrying handle alas.



Z

 

No vent holes on the battery? Or no vent tube provided by the owner?

And handles for your cocoon are available at Home Depot. See below. I'd use two hands.

 

My current AMG (absorbed glass mat) battery is a NAPA branded battery. Those, and all the Optima AGM batteries I’ve seen have no typical external vent that one would connect to a vent tube. That, and their unique construction is what allows them to be installed in any position.

Under normal conditions in AGM batteries, all the Hydrogen and other gasses created by regular charging are re-absorbed internally by the absorbent glass mat. If an overcharging situation develops they WILL vent externally. I don’t know the exact mechanism for that happening. Nevertheless, that’s the reason that even AGM batteries should never be installed in an airtight compartment.

Z

 

The Bosch AGM battery I installed in my wife's 2006 XK8 in July 2018 is indeed vented....

 

I'll keep my setup as is. I had a 50 foot string of LED christmas lights on a plug in timer last year. Not sure what happened but the timer melted. Thankfully it was on a gfci outlet and the outlet tripped. Granted, it was a cheap timer from a "tool discount store" so don't buy a cheap one. As part of my monthly checks, the battery vent system is one of the items looked at.
Your point about checking the vent should serve as a good reminder to all.

 

Interesting, didn't know that about the Optima form/construction. All of my AGM batteries have the standard vent holes (7 cars).

 

it would be interesting to hear what the manufacturer of those ‘vented” AGM’s have to say about the internal plumbing in their batteries. I bet a dollar to a dime that any such visible vent is only activated during an overcharging situation.

if they were constructed like a traditional battery, then a continuous vent would make them a “maintenance “ battery, which need the occasional addition of distilled water to replace the volume of vented gasses lost out the vent.

All true AGM’s are classified as “maintenance-free” because under normal charging conditions ALL hydrogen and other secondary gasses created by the charging process are re-aborted into the glass mat windings. They don’t escape out any vent, and therefore don’t need replenishment.

Z

 

I'm pretty sure that's true, I believe they are valve vented and only open at something like 1-2 psi.

 

same with my Bosch AGM, two vent ports. it is nice that if the pressure relief must occur, the gas is directed out of the compartment.

two things that i never wish to experience again: a battery explosion and the other one was named . . . .

 

If you have a Amazon Prime account, the NOCO Genius G3500 will be on sale for $35 (reg $80) until 11/23/19. High Reviews, has multi modes for wet/agm/lithium, 6v and 12v, and also a battery repair function to de-sulfate. Also semi-water resistant if used outside. I'm in for a couple; one for me one for a gift.

Looks like an insane deal:

https://tools.woot.com/offers/noco-m...f=w_cnt_wp_5_1