AGM batteries- hydrogen gas?

[OldGuyNewJeep]

Not a Jeep specific question, but our JLs do come with AGM batteries.

As sealed, “maintenance free” batteries, do they still have the same explosion risk as old school flooded batteries?

Why I ask: I had to jump start my wife’s Yukon, yesterday, and it has an AGM battery. There was no unpainted metal under her hood that I could reach with my cables. I had to grit my teeth and connect negative to negative (I was at least wearing safety goggles and long sleeves).

Do AGM batteries even leech hydrogen gas when the deplete?

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[ctJLnewbie]

My experience with AGM batteries comes from boating. In some use cases, offshore/around the world sailboat racing, at one point AGM was required because it was so much safer than lead acid. Now technology has moved even further with super exotic Lithium blends (and they are finicky / get dangerous if you don't treat them just right). But the AGMs are still a standard for safety.

 

[dsgrey]

My experience was with my Miata where they place the AGM battery in the trunk and have a tube off the battery to vent outside. AGM's give off hydrogen and I suspect they would if fully depleted (dead/expired) and I suspect your Yukon battery was not depleted but just low.

 

[OldGuyNewJeep]

My experience was with my Miata where they place the AGM battery in the trunk and have a tube off the battery to vent outside. AGM's give off hydrogen and I suspect they would if fully depleted (dead/expired) and I suspect your Yukon battery was not depleted but just low.

Oh, it was deader than a doornail. GM has OnStar, which is pretty neat... it emailed me to let me know the battery was dying a few days ago. I put it on a tender and let it fully charge, but it still couldn’t crank the engine. (Odd thing is that my multimeter shows it has 12.6 volts. I guess under load it must plummet. It would have been interesting to watch multimeter while I cranked the engine, but I was all alone.)

Part of my problem was that it was stuck in my garage and my cables could only just reach.

Anyway, I put in a new Interstate battery and all is well. I also found a decent ground point for next time, but I was curious if this was even a valid worry for AGMs; sounds like it is.

Maybe this is a good excuse for me to buy one of those Noco jump starters.

 

[Headbarcode]

There's nothing at all wrong with hooking both the + and - leads directly to the battery being charged or jumped. There's already a built in ground strap from the - battery terminal to the chassis.

Glad to hear your sorted out, just throwing this in for future reference.

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