Ditto with the YES...vent your battery. I'd do it whether it was an lead/acid battery or an AGM battery (if it has the little hole for the vent tube to hook up to).
When hydrogen off gases are releases from the battery, it can cause corrosion as well as an explosion (can occur is a spark results from an overcharge situation from the althernator...which can commonly occur from normal driving)
(battery exploded from non venting of battery in an e38)
(corrosion damage from shoving battery into place without hooking up vent tube in an e38) Image by: SOBEK (bimmerforums)
(and more corrosion at end of vent tube that has been pulled up and not vented completely to the exterior of the vehicle...also on an e38)...images by
cyclops (bimmerboard) just posted
10/25/13
As far as the "vent kit"...only the top venting batteries come with a "kit...which extends over from the top center of the battery to meet up with the vehicles vent tube that snakes its way to the exterior of the vehicle. If the battery vents from the side like the original battery...then all you need is the little black elbow that originally came with the car to connect the replacement battery to the vehicle's vent tube:
Item #2 (BMW part #
61 21 1 377 835) is the little elbow that goes in-between the vehicle's vent tube and the battery...it costs between 52¢-$1.50: