WTF! "Glass pack battery"

[ItsOnlyMoney]

So ok, the battery in my 2005 530 was going south (but didn't the manual say the batery was designed for the life of the car - no joke). It's the second battery, the first replaced under warrenty. Maybe start another thread with that topic.
Anyway, I followed advice here and bought a recommended battery from AutoZone for about $100. It was close to the original CCA and a little shorter in size. Right after replacing the battery, I took the car into an independent shop that I trust here in Orlando and they said the battery was not the "right type". It could build up gas and expload. They offered a glass pack battery for $200. I took it and returned the other. The guys at AutoZone were great about refunding my purchase but said that the selling the real expensive battery was a load of crap. Who to believe? Hate to lose someone I can trust servicing this car.
Opinions welcome.

[BBenedict]

A good explaination of auto batteries can be found here:

Battery Tutorial

[gidgaf]

I'm sorry- I just laughed at you.
You was taken. MAYBE if the battery was installed in the glove compartment gas could accumulate to a dangerous level. But not in the stock location.
Newer tech batteries ARE sometimes smaller than the old ones they replace. Mostly. The one in my 30 year old truck is maybe 3/4 the original size but still with more CCV. Granted the glass packs are a little more heavy duty- but that's a $100 wasted for a a not needed function.

[AlpineSixAndSeven]

^ do you know what your talking about? the batterys in these cars are mounted in the trunk..... there is a vent tube athat is you get a cheapo battery or the wrong one it will not have the proper vent tube thus gas builds up in the barrey compartment in the trunk. Please Dont post incorrect information Thanks Oh and batterys have class sizes so the correct fitting battery(not just a close enough) will be the same size

[gidgaf]

*There is no magic BMW battery. Does it fit in place, can it get buttoned down, does it have enough CCA, can you connect it, and will the vent work? Sofa King Good! I used to hotrod, and I'd put the battery in a vented box in the trunk or on the floor, and there's no mystery science involved. You CAN get "ventless" glass pack batteries- bikers and hotrodders like to get them because you can mount them on their side, or even upside down, if that's the best way to access the terminals.
*I still believe the guy got took. IF you plug up the vent the battery could explode. IF you don't vent the battery to the outside you could experience vapors and fumes in the trunk. IF you apply some common sense these things won't occur.