To plug the battery vent hole, use silicone sealant or caulk on the negative side. Make sure the positive side has the vent hose connected to a 90-degree elbow.
How do I replace a flooded lead acid battery?
Most Flooded Lead Acid (FLA) batteries that are sealed and vented have a hole in EITHER END, so you need to make sure your replacement battery has a PLUG inserted in the Rear end (Negative Post) or the vent tube is for nothing. Most "International" or Vented Batteries come with both the elbow and plug, and some come with a new vent tube.
Does charging a lead acid battery produce gas?
Yes, lead acid batteries give off gas when being charged. It is recommended to drill a few small holes in the battery box, if it doesn't already exist, for ventilation. The van manufacturer might assume a new 'fangled' battery is being used and may not have provided proper ventilation for it. Yes, this specific battery (identical to the one mentioned) needs to vent.
Do all AGM batteries come with a vent tube?
Most "International" or Vented Batteries come with both the elbow and plug, and some come with a new vent tube. ANYONE who can advise: Does the AGM battery have the same vent tube setup described above? Does your car currently have an FLA or AGM Type battery? Do you know the size & Ah rating of the battery currently installed?
For vehicle applications that have the battery installed inside the passenger compartment of a vehicle, it is imperative the battery be vented properly. For those applications that have a single vent tube, the opposing vent opening on the battery cover must be plugged with the included vent hole plug.
In those applications, the battery must be vented to the outside via a breather tube. It vents the hydrogen gas out of the vehicle for safety reasons. Vented batteries have vent holes on both sides so you can attach the vent tube where you need it. Yet another reason why in-cab batteries make no sense
Which battery is similar to a sealed battery?
The closest battery to a sealed battery is the VRLA or valve regulated lead acid or gas recombination types. These batteries have vents but will only vent off if abused. They can often be used on their sides or even upside down as they don't have free electrolyte, like some AGM or Gel batteries.