For anyone wondering whether battery vent plugs should or shouldn’t be removed upon installation, here’s some photos.

 

This battery is possibly only 4 weeks old. It has done less than 500 miles in that time.

 

One of the vent plugs was left in, one was removed. Not by me, I should add. By a main Skoda dealer.

 

You can tell by the bulge of the battery what side the plug was left in!

 

 

 

Hello, welcome to the forum.

These batteries are designed to be sealed, that's why they are called SLA/VR type (sealed Lead Acid/ Valve Regulated) - they will vent by blowing out the vent plug if abused by overcharging.

The sealed design is to allow the gases generated during charging or high discharge to recombine rather than being lost to atmosphere and losing electrolyte.

Edited 17 October, 20241 yr by Warrior193
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38 minutes ago, Warrior193 said:

 they will vent by blowing out the vent plug if abused by overcharging.

@AndyC13 I would get your alternator & BMS checked out as it might be overcharging if it can do that to a battery in only 4 weeks.

1 hour ago, PetrolDave said:

@AndyC13 I would get your alternator & BMS checked out as it might be overcharging if it can do that to a battery in only 4 weeks.

The battery could be anything from 4 weeks to 2 years old.

 

When the vehicle was purchased last month, second hand, a note on the service history says there were problems starting the car.

So either the battery was already faulty and was jump started, or the battery was replaced last month.

 

The battery seems new and is relatively clean, but it’s a low mileage car so hard to ascertain the age.

2 hours ago, Warrior193 said:

Hello, welcome to the forum.

These batteries are designed to be sealed, that's why they are called SLA/VR type (sealed Lead Acid/ Valve Regulated) - they will vent by blowing out the vent plug if abused by overcharging.

The sealed design is to allow the gases generated during charging or high discharge to recombine rather than being lost to atmosphere and losing electrolyte.

The vent plug was well seated, so maybe hasn’t blown out like it should have. Instead, the side of the battery itself has blown out and bulged.

2 hours ago, Warrior193 said:

they will vent by blowing out the vent plug if abused by overcharging.

 

1 hour ago, PetrolDave said:

@AndyC13 I would get your alternator & BMS checked out as it might be overcharging if it can do that to a battery in only 4 weeks.

 

2 minutes ago, AndyC13 said:

The vent plug was well seated, so maybe hasn’t blown out like it should have. Instead, the side of the battery itself has blown out and bulged.

The vent plug should only need to blow out in the event of overcharging - so I stand by my comment that you need to get the charging system looked at - first step is to check the voltage with a multimeter with the engine running, if it's over 15V then you definitely have a problem.

1 hour ago, AndyC13 said:

The battery could be anything from 4 weeks to 2 years old.

 

When the vehicle was purchased last month, second hand, a note on the service history says there were problems starting the car.

So either the battery was already faulty and was jump started, or the battery was replaced last month.

 

The battery seems new and is relatively clean, but it’s a low mileage car so hard to ascertain the age.

There could possibly be a date stamp on the top of negative terminal = WW.YY.