What’s this?

Giving the boot of my Mk2.5 a good clean and found this tube next to the battery. Anyone know what it is and should it just be next to the battery?

It’s the breather/ vent tube that should be attached to a non sealed battery

It’s the tube to vent battery gasses to the outside. Yes, it should be connected to vent pipes either side of the battery. What battery have you got?

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Bosch S4 001

I have the S4 001 too, with vent pipes disconnected. Be interested to know if this battery should be vented.

A search in the battery specs/data (Bosch) say they are maintainence free, the special lid recirculates/returns any gasses back inside the battery.

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Thanks all.

Maintenance-free just means that most of the gasses generated by the charge/discharge cycles are re-combined within the battery and you don’t have to top-up the electrolyte. In normal operation some gases escape via pressure-release valves (vent holes). Even fully-sealed batteries have emergency valves to prevent over-pressurisation in fault conditions.

These gases are acidic and potentially explosive, so if a battery is located in (closed) passenger/luggage compartments rather than the (open) engine bay, the gases must be vented to the outside.

The S4 001 appears to have these vent holes on each side. You must connected these to the tube in your photo.

Google “car battery vent hole” and “car battery maintenance free”. if you want more info.

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I could be useful to know if the OP managed to fix the vents to this S4 001 battery or even if they found any?

My vent pipes are too large a diameter to fit in what are the (presumably) vent holes on either side of the S4 battery. I have some spare windscreen washer pipe joiners that may fit inside the holes. Will test it tomorrow.

I cut the end off an electrical spade connector. The type you crimp on. They have a slightly different diameter each end. Worked well.

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I replaced the useless Westco battery with a Bosch S4 as well. I used a couple of right-angled washer pipe connectors with the ends that go into the battery vent holes wrapped a bit with electrical insulation tape to increase the diameter a fraction, and substituted the Mazda rubber pipes from the T-junction with the clear plastic type.

Laurie


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Good idea. Mine looks similar.
Just out of interest, what are the other 2 wires to the battery terminals?