I used a large rubber stopper from the local hardware store for years on my 6 volt battery. I even used a very small diameter plastic tube (from a carb cleaner spray can) for venting. A small V shaped cut on the side of the rubber stopper was added for the vent tube.
Bob-A
Now THAT'S an interesting solution. Thanks for sharing!
Chris
I have an old battery in my garage. I can look at the caps and put a couple in the mail to you if I have your address.
Thanks. Been all over Google to no avail.Google could be your friend??
Paul in CT