Leisure Batteries draining?

[AlisonF]

My T6 is 3.5 years old. The leisure batteries have been charged regularly and it is driven regularly too.
The leisure batteries had never shown below 70/80% before, even after camping 2-3 nights (fridge turned up high etc).
It was in the garage recently and when they delivered it back I noticed the control panel flashing - leisure batteries empty. I mentioned it (amongst other issues) to the dealer and said I thought the batteries would be ruined. They charged them up when they took it in to correct other issues and said they thought they were fine.
On regular use they are dropping to 80/90% overnight which had me worried. Last night I put the heater on level 5 overnight to test the batteries. 12 hours later they are at 40%. This is not what I would expect, certainly not what I was getting previously.
Did draining the batteries

 

[Hotel California]

Could be running on just one instead of two battery's , maybe they blown a fuse while working on the Cali at dealer?

 

[AlisonF]

Could be running on just one instead of two battery's , maybe they blown a fuse while working on the Cali at dealer?

They had the whole thing apart as the 12V sockets weren’t working after the tow bar was fitted last year... so had to follow electrics through to find what went wrong with that...
it seems that each time they ‘solve’ one issue they create a few more...

 

[WelshGas]

They had the whole thing apart as the 12V sockets weren’t working after the tow bar was fitted last year... so had to follow electrics through to find what went wrong with that...
it seems that each time they ‘solve’ one issue they create a few more...

There is a 50amp Cube fuse on the +tve pole of the rear Leisure Battery. Get this checked out. Sounds as if you could be running on 1 battery only.
When you said the Control Panel was showing 40% what was the voltage?
Were the fridge and heater still working? At 40% both should have switched Off below 11.5v.

 

[AlisonF]

There is a 50amp Cube fuse on the +tve pole of the rear Leisure Battery. Get this checked out. Sounds as if you could be running on 1 battery only.
When you said the Control Panel was showing 40% what was the voltage?
Were the fridge and heater still working? At 40% both should have switched Off below 11.5v.

I didn’t check the voltage - will do it all again once charged and make note of that as well as perrcentage.
The fridge was not on. Only the heater. It had been working overnight as I could hear it from the house (light sleeper). But that doesn’t say it hadn’t shut off just before I went out to check on it this morning...
Numpty question, if it turns out I’m running on one leisure battery only, how does it manage to say 100% when fully charged?

 

[WelshGas]

I didn’t check the voltage - will do it all again once charged and make note of that as well as perrcentage.
The fridge was not on. Only the heater. It had been working overnight as I could hear it from the house (light sleeper). But that doesn’t say it hadn’t shut off just before I went out to check on it this morning...
Numpty question, if it turns out I’m running on one leisure battery only, how does it manage to say 100% when fully charged?

Because the 1 battery connected is at 100%. It is a very simple system and not sophisticated to know that the 2nd battery is not connected.

 

[KGCali]

There is a 50amp Cube fuse on the +tve pole of the rear Leisure Battery. Get this checked out. Sounds as if you could be running on 1 battery only.
When you said the Control Panel was showing 40% what was the voltage?
Were the fridge and heater still working? At 40% both should have switched Off below 11.5v.

As @WelshGas stated there is a large fuse on the + terminal of the leisure battery, see picture, so worth checking with a multimeter that it's not blown.

 

[AlisonF]

As mentioned under the dealer review thread, the van was due in to have batteries checked Thursday / Friday but they didn’t show up. So rescheduled for next Thursday / Friday.
I am using the van, not daily, but 2-3 times a week for 30-60mile round trips and almost daily for short trips.
The last three days I have used the heater (on remote) to defrost the van before heading out. Each time the heater was on level 4 and for between 30 and 40 mins. On Friday (after the defrost) I did a 60 mile round trip. Yesterday was shorter but I didn’t check the battery level (shouldnt need to !). Today the heater was on for 40 mins and when I got in the battery was down to 20%...
I’ve put it on charge overnight (which I do every 4-6 weeks even though driving it regularly).
@WelshGas said the battery switches off below 40%... if I understood correctly. But today the heater was still going when the battery level was 20%.
As I’ve said before, the batteries never got below 70-80% even after a couple of nights without hook up. But since they were drained by VW during a warranty issue, they are simply not holding charge.
If anyone can give me info on how much charge they should be holding and for how long, after being fully charged, let me know please. Thank you

 

[KGCali]

Check the cube fuse on the rear leisure battery terminal hasn't blown as you may only be running on one of the two batteries.

 

[AlisonF]

Check the cube fuse on the rear leisure battery terminal hasn't blown as you may only be running on one of the two batteries.

I’m hoping that’s what the dealer will do. Thank you. I’m refusing to touch anything as they will try to blame any faults on me...
Is there any reason why you say the rear one? As it was the front one (under passenger seat) they touched fitting the towa bar electrics (and disconnecting all the 12V sockets in the process)...

 

[MartG]

Is there any reason why you say the rear one? As it was the front one (under passenger seat) they touched fitting the towa bar electrics (and disconnecting all the 12V sockets in the process)...

The rear one has the 'cube' fuse fitted, the front doesn't. Both batteries are wired in parallel with only the rear one fused. The capacity (time to discharge) will be halved if it blows.

 

[WelshGas]

As mentioned under the dealer review thread, the van was due in to have batteries checked Thursday / Friday but they didn’t show up. So rescheduled for next Thursday / Friday.
I am using the van, not daily, but 2-3 times a week for 30-60mile round trips and almost daily for short trips.
The last three days I have used the heater (on remote) to defrost the van before heading out. Each time the heater was on level 4 and for between 30 and 40 mins. On Friday (after the defrost) I did a 60 mile round trip. Yesterday was shorter but I didn’t check the battery level (shouldnt need to !). Today the heater was on for 40 mins and when I got in the battery was down to 20%...
I’ve put it on charge overnight (which I do every 4-6 weeks even though driving it regularly).
@WelshGas said the battery switches off below 40%... if I understood correctly. But today the heater was still going when the battery level was 20%.
As I’ve said before, the batteries never got below 70-80% even after a couple of nights without hook up. But since they were drained by VW during a warranty issue, they are simply not holding charge.
If anyone can give me info on how much charge they should be holding and for how long, after being fully charged, let me know please. Thank you

The % calculated is not that accurate, but the voltage is.
You mention the % was 20%, but what was the voltage showing?
The Control Panel % seems to get more inaccurate the longer the Control Panel is left On.
i believe it should be Reset on a regular basis if left On.

 

[WelshGas]

I’m hoping that’s what the dealer will do. Thank you. I’m refusing to touch anything as they will try to blame any faults on me...
Is there any reason why you say the rear one? As it was the front one (under passenger seat) they touched fitting the towa bar electrics (and disconnecting all the 12V sockets in the process)...

The fact that they were fiddling under the Front Passenger is highly suggestive that the Rear Cube fuse should be checked.
The numpty probably disconnected the Front Battery and didn’t think or didn’t know that the red +tve cable was still live, due to the Rear Leisure Battery.

 

[AlisonF]

The % calculated is not that accurate, but the voltage is.
You mention the % was 20%, but what was the voltage showing?
The Control Panel % seems to get more inaccurate the longer the Control Panel is left On.
i believe it should be Reset on a regular basis if left On.

Since you mentioned it I have been checking the voltage - but on this occasion was starting the engine and just glanced at the control panel so didn’t see more than the 20%... before they messed it up, the battery had never been below around 70%, even after a couple of nights camping (fridge, heater, lights).
It’s schedule to go in (if they remember to collect it this time!) this week...

 

[Loz]

Use the voltage with this chart as a better gauge.

 

[MattBW]

If you have access to a multimeter, then just check the front battery adn rear battery voltages separately. This will give you an instant idea if the voltages don't match there is probably a blown rear fuse.

 

[AlisonF]

If you have access to a multimeter, then just check the front battery adn rear battery voltages separately. This will give you an instant idea if the voltages don't match there is probably a blown rear fuse.

Thanks. I’ll ask them to do it so I don’t get any “you need to prove it” type comments again. I’m not touching anything on principle. Sadly.

 

[AlisonF]

Thank you for all the helpful tips so far. The van (hopefully, if they remember this time...) will be back in tomorrow.
So, I can ask them to check the fuse for the rear leisure battery. It does look like that may have been blown when they disconnected front leisure battery to install towbar / correct towbar installation as it resulted in loss of 12V sockets.
However, I am still concerned the batteries themselves may have been damage, as when I received the van back the bottom right of the control panel was flashing a plug, indicating the batteries were empty and needing charging...
So, what tests should I be asking the dealer to assure me that neither leisure battery has been ruined as a result?
Thanks in advance.
@Loz @WelshGas @VW Guru

 

[MartG]

The leisure batteries need to be fully charged, followed by a steady discharge, monitoring their capacity as they go. They should last around 2x each batteries Ah rating, so if they are each 80Ah, then 160 hours at 1A, which will see them drop from 100% to 0%. I would expect your batteries to last for 4-5 days using the fridge, lights and occasional heater. Don't let them go beyond 11.8V, charge immediately after. You'll get a good idea if they are performing as well as they were before.

A proper test for an auto electrician is to put a known load on them and time their discharge voltage drop.

Please reply on the forum your outcome. I can maybe help as I'm in Aberdeen now and again...

edit - to reflect the 80Ah rating confirmed by WG

 

[AlisonF]

The leisure batteries need to be fully charged, followed by a steady discharge, monitoring their capacity as they go. They should last around 2x each batteries Ah rating, so if they are each 75Ah, then 150 hours at 1A, which will see them drop from 100% to 0%. The 75Ah rating is not really their usable capacity but the capacity until flat. I would expect your batteries to last for 4-5 days using the fridge, lights and occasional heater. Don't let them go beyond 10.8V, charge immediately after. You'll get a good idea if they are performing as well as they were before.

A proper test for an auto electrician is to put a known load on them and time their discharge voltage drop.

Please reply on the forum your outcome. I can maybe help as I'm in Aberdeen now and again...

Thank you. I believe the plan is to charge them and then watch the drop...
The bit that concerns me (and I may be wrong) is the fact the batteries were drained and that can influence the leisure battery life...
The performance was great before this.
I’m still under extended warranty and if they have caused a reduced functionality of the batteries through their work, I would like to be able to demonstrate that...
Great to hear you’re in Aberdeen now and then. If you wanted to get in touch, feel free to PM me. Thanks again.

 

[MartG]

Ideally, you need to measure the voltage of each battery with them disconnected. If one or other is below 11.8 V, and it hasn't been charged for a while (eg, blown fuse), then it's capacity could have been lowered through sulphation. If the voltage is above 11.8V and not that long since last charged, you should be fine...

I wasn't aware that the panel shows a flashing charge plug before. Not sure at what voltage that pops up -Anyone got any info on that?

 

[AlisonF]

Ideally, you need to measure the voltage of each battery with them disconnected. If one or other is below 11.8 V, and it hasn't been charged for a while (eg, blown fuse), then it's capacity could have been lowered through sulphation. If the voltage is above 11.8V and not that long since last charged, you should be fine...

I wasn't aware that the panel shows a flashing charge plug before. Not sure at what voltage that pops up -Anyone got any info on that?

So they charged them overnight (I’d already charged on hook up earlier in the week and been driving). Then called me today to say they were fully charged and what was the issue again...? So I explained they were losing charge too quickly.
Their proposal is to fully charge it, and another Cali, have both overnight with heater on and see what the batteries say in the morning on the two Cali’s... so not exactly what I would call a proper drain test...?
They wanted to do it overnight tonight, but I was promised the van back today and need it over the weekend, so the experiment will be next week...
Any more advice on how the battery drain test should be conducted would be welcome.

 

[Lightning]

Use the voltage with this chart as a better gauge.
View attachment 53156

This chart doesn’t correspond to my control panel display readout.

 

[AlisonF]

And delivered back like this... having not done a drain test...

 

[Loz]

You need to insulate that terminal! So I expect the 80A fuse at the front is now blown if that terminal has touched ground.