Another Basic Battery Question.

I recently posted a question on here about changing a battery on my brother's 2006 Merc E220 to one of a higher output. All is well, and I'm grateful for the help I received.

However, I have some more questions. The car's battery is fitted in the boot on these cars. There is a breather tube for the gases produced when charging that pushes into a small vent hole on one end of the battery near the top.

On the new battery were stickers saying to remove the two plugs from the battery's vent holes before use - one hole at either end. As there's only one breather tube to fit one of the vent holes on battery, what do I do with the other vent hole on battery? Follow the instructions and remove plug - but then the open hole will be venting into the boot? Or leave the plug in?

I'm wondering if the two vent holes on battery are interconnected inside battery, which means it won't be a problem if only one vents and the other is plugged. Or if one vent hole serves the cells on one half of the battery, and the other hole serves the cells on other half of battery. In which case it wouldn't be a good idea to keep one plugged.

Apologies for the long post on such a simple problem. All my cars have had batteries under the bonnet which wouldn't be a problem with venting.

you probably should buy another length of breather tube and either run it alongside the original one to the outside or join them both with a Y connector (something like https://www.ebay.co.uk/itm/Y-Piece-...-Healey-Sprite-MG-Midget-12G2134/352360601515 ) to link the 2 into 1.

are you sure you read it right?

IIRC my last battery had a plugged vent hole at each end, and you only unplug the one you want to use.

Mine are Varta and they have a very helpful tech support.

Im certain the battery cells are joined by the manifold on the top, so only one vent is needed.
John

Burnerman said:

Im certain the battery cells are joined by the manifold on the top, so only one vent is needed.

Click to expand...

An easy test to prove this is to blow into one side (probably using a cleaned length of the battery vent hose) and see if you get air coming out of the other side.

Is there any bother running two pipes, one for each vent hole?

No, not at all....so long as any fumes don’t get into contact with metal, all will be fine. One battery will fit several installations, hence the option.
John