Help diagnosing leisure battery drain

[Bob Petttitt]

Many thanks MartG ! Will check tomorrow mate, although I'm sure you're correct - Every day's a school day. (I used to think Top Cat was totally cool too btw)
Cheers,
Bob

 

[MartG]

Thanks Bob. Our pet cat is called Spook!

 

[Bob Petttitt]

If I had a cat I'd call it Chooch - He was so cool.

 

[MartG]

Haha - our other cat is ChooChoo! (Chooch)

 

[ainsy]

You get Priority Service via VW Assistance. If something needs doing that the VW Assistance Guy cannot sort then immediate / priority appointment at Dealership.

I've had VW assist out twice now and they can't work out why the batteries are draining so it's off to the dealer (no priority appointment though!)

Some interesting points VW assistance said:

> AGM batteries don't sulfate like traditional lead-acid batteries and can be drained without causing damage.
> The VAS 6161 battery tester confirmed all batteries are in good condition
> He was convinced 'something' was draining the batteries but didn't know what
> He also stated all 3 batteries (2 leisure and 1 starter) are all the same AGM batteries. I was surprised the starter battery was the same type.

I asked the question if something was draining the battery why does the console only show -0.2A drain, which is just the drain from switching the console on. He couldn't answer this.

Does anyone know if the batteries could be being drained without the console registering the drain?

Thanks everyone for your help so far.

 

[Lightning]

I've had VW assist out twice now and they can't work out why the batteries are draining so it's off to the dealer (no priority appointment though!)

Some interesting points VW assistance said:

> AGM batteries don't sulfate like traditional lead-acid batteries and can be drained without causing damage.
> The VAS 6161 battery tester confirmed all batteries are in good condition
> He was convinced 'something' was draining the batteries but didn't know what
> He also stated all 3 batteries (2 leisure and 1 starter) are all the same AGM batteries. I was surprised the starter battery was the same type.

I asked the question if something was draining the battery why does the console only show -0.2A drain, which is just the drain from switching the console on. He couldn't answer this.

Does anyone know if the batteries could be being drained without the console registering the drain?

Thanks everyone for your help so far.

AGM batteries do sulphate. From the Tanya website, who VW source their LA80 batteries from:
1. Never leave your battery in a discharged state
When a battery has been fully charged it can quite happily be stored away for 2-3 months. However when a battery is flat, storing it for this period would almost certainly damage it beyond repair.
The reason behind this is a chemical process called sulphation. When a battery is charged this chemical process cannot take place. However, when the battery's voltage falls below 12.4V this process begins. The process causes sulphur crystals to form on the lead plates inside the battery, which in turn increases the battery's electrical resistance. The longer this process is allowed to continue the worse the effect. Eventually the battery will become so electrically resistant, that you will be unable to charge the battery, let alone draw power from it.
If this process is caught early you may be able to salvage the battery using a battery charger with a pulse charge function. This will partially break down the sulphur crystals but the battery will never reach its full capacity again.
Remember that if your battery fails due to sulphation it will not be covered under warranty. This kind of failure is classed as damage caused by the user through neglect.

 

[Hotel California]

If your Cali is new and still has warrenty VW should sort this out , if no draining is found then it's simple and battery's are gone and should be replaced .

 

[ainsy]

AGM batteries do sulphate. From the Tanya website, who VW source their LA80 batteries from:
1. Never leave your battery in a discharged state
When a battery has been fully charged it can quite happily be stored away for 2-3 months. However when a battery is flat, storing it for this period would almost certainly damage it beyond repair.
The reason behind this is a chemical process called sulphation. When a battery is charged this chemical process cannot take place. However, when the battery's voltage falls below 12.4V this process begins. The process causes sulphur crystals to form on the lead plates inside the battery, which in turn increases the battery's electrical resistance. The longer this process is allowed to continue the worse the effect. Eventually the battery will become so electrically resistant, that you will be unable to charge the battery, let alone draw power from it.
If this process is caught early you may be able to salvage the battery using a battery charger with a pulse charge function. This will partially break down the sulphur crystals but the battery will never reach its full capacity again.
Remember that if your battery fails due to sulphation it will not be covered under warranty. This kind of failure is classed as damage caused by the user through neglect.

This is what I thought. I personally believe the batteries have been damaged and this is why they also get very hot when I charge off EHU.

I've received some really dodgy information from VW. The dealer told me to drain the batteries and recharge to get rid of any 'memory effect' problems on the batteries. This was complete nonsense, which I ignored.

The problem is all VW assist will do is quickly run the VAS 6161 battery test

 

[Lightning]

This is what I thought. I personally believe the batteries have been damaged and this is why they also get very hot when I charge off EHU.

I've received some really dodgy information from VW. The dealer told me to drain the batteries and recharge to get rid of any 'memory effect' problems on the batteries. This was complete nonsense, which I ignored.

The problem is all VW assist will do is quickly run the VAS 6161 battery test

I had this, went flat at a festival and were never the same again. VW claimed they were fine and refused the warranty claim. I’ve just replaced them both myself with the Tanya batteries and now they are fine.

 

[MartG]

I asked the question if something was draining the battery why does the console only show -0.2A drain, which is just the drain from switching the console on. He couldn't answer this.

Does anyone know if the batteries could be being drained without the console registering the drain?

All lead acid cells will suffer sulfation, it's a chemical reaction to not being fully charged.
I've not used a VAS 6161 tester before but it should have picked up any issues. Like any tool, it requires it's user to know what they are doing!
Starter batteries can be AGM - used more for start/stop vehicles these days.

If any of the cells have internal shorting (low internal resistance), likely due to sulfation, this will not show as current draw on the console panel and will cause the heat during re-charging.

I'd recommend a second opinion from another VW dealer or auto electrician...