Thoughts on leisure batteries not holding charge?

David Eccles · Jun 24, 2021

Okay I've looked at related threads which seem to be on T6 and newish vans..and not really what I have
This is on a 2011 T5
Leisure batteries seem not to hold charge
dealership charged fully and tested and report batteries are in really good condition for age
Also tested the micro switching charge system, all OK
Probable cause diagnosed as lack of use and not charging fully for 12+ hours on hook up and journeys not long enough to put full charge in; sounded feasible.
Returned on Monday to me fully charged.
Tuesday did 150 mile trip to seaside (very nice). No use of batteries for roof or fridge etc. Display panel is off.
Today (Weds) I happened to check when cleaning to find batteries are down to 70%.
Dealer will be taking back in (in 2 weeks!!!) to fully charge and then monitor any drain for 2 days to see if they can find an issue.
But am just wondering if anyone has any ideas on possible cause .... eg are they actually knackered despite dealer saying they are good?
What should they be checking?

WelshGas · Jun 24, 2021

David Eccles said:
Okay I've looked at related threads which seem to be on T6 and newish vans..and not really what I have
This is on a 2011 T5
Leisure batteries seem not to hold charge
dealership charged fully and tested and report batteries are in really good condition for age
Also tested the micro switching charge system, all OK
Probable cause diagnosed as lack of use and not charging fully for 12+ hours on hook up and journeys not long enough to put full charge in; sounded feasible.
Returned on Monday to me fully charged.
Tuesday did 150 mile trip to seaside (very nice). No use of batteries for roof or fridge etc. Display panel is off.
Today (Weds) I happened to check when cleaning to find batteries are down to 70%.
Dealer will be taking back in (in 2 weeks!!!) to fully charge and then monitor any drain for 2 days to see if they can find an issue.
But am just wondering if anyone has any ideas on possible cause .... eg are they actually knackered despite dealer saying they are good?
What should they be checking?

How old are the batteries?
What voltage and current draw shown on the Control Panel, with nothing switched on and at least 1 hr after engine switch off or disconnection from Mains Hookup?

andyinluton · Jun 24, 2021

Have you got anything plugged in the inverter socket - doesn’t need to be something switched on, just a
Plug adapter is enough to turn the inverter on even if you then don’t have anything plugged into it.
Other things we’ve found that drain the battery are USB adapters in the 12v sockets.

Either of the above should show as a drain ie outgoing current on the overhead display.

David Eccles · Jun 25, 2021

I'll go and check all the readings later but nothing is plugged in...

andyinluton · Jun 25, 2021

David Eccles said:
I'll go and check all the readings later but nothing is plugged in...

With everything turned off, try disconnecting one of the leisure battery leads, if you can get a spark it would show that there is current flowing.

David Eccles · Jun 25, 2021

OK this is 24 hours on..still showing 70%

WelshGas · Jun 25, 2021

David Eccles said:
OK this is 24 hours on..still showing 70%View attachment 80615

Are the batteries original?
If so, then 10 yrs is good going.

David Eccles · Jun 25, 2021

Yes..which is why I suspected it would be replace time! But dealer was very clear in saying they tested out as A1 and actually commented on fact they were in such good condition considering their age!
Now I being suspicious and wondering if they were tested properly and looked at after 24 hours as promised or if twas just a fob off..
am going to monitor display readings for a couple of days and write to service manager to enquire how long they actually waited from 100% charge to sending back - they had it for five days but were hard to pin down in that period...they say batteries were on full charge of 100% when returned but like a dummy I did not check that!

Ozzy Pete · Jun 26, 2021

David Eccles said:
Yes..which is why I suspected it would be replace time! But dealer was very clear in saying they tested out as A1 and actually commented on fact they were in such good condition considering their age!
Now I being suspicious and wondering if they were tested properly and looked at after 24 hours as promised or if twas just a fob off..
am going to monitor display readings for a couple of days and write to service manager to enquire how long they actually waited from 100% charge to sending back - they had it for five days but were hard to pin down in that period...they say batteries were on full charge of 100% when returned but like a dummy I did not check that!

I don’t see why the dealer would tell you they are ok when they aren’t.Hes losing a possible sale of 2 leisure batteries at £250 each. I take it that the testing and checking resulted in a bill from the dealer? How long do they stay at 70% ?

apreading · Jun 26, 2021

Ozzy Pete said:
I don’t see why the dealer would tell you they are ok when they aren’t.Hes losing a possible sale of 2 leisure batteries at £250 each. I take it that the testing and checking resulted in a bill from the dealer? How long do they stay at 70% ?

I take it as the dealer they bought the van from told them they were tested and OK. And they now suspect that dealer may have just told them that so the dealer didnt have to replace them prior to sale. Correct?

David Eccles · Jun 26, 2021

no....we have had the bus from new!
I am just wondering if they had so much work they couldn't really be bothered to keep it in taking space in workshop for standing time, and as batteries seemed to test out OK they just charged it and sent it home (not for free of course!)
It's still reading 70% and not been used for 5 days
Dealer's plan is to fully charge batteries...and monitor over next 48 hours to see if hold charge and see if any drainage..
which is what I thought they would do first time...
Its 2 weeks till goes in, next plan is to put on hook up for around 18 hours and see if I can get a 100% at home and then see what happens...
I could just simply wait till it goes in again but its niggling my brain....

AlisonF · Jun 26, 2021

@David Eccles I think the general advice from the forum is to follow the voltage rather than the percentage (apparently it’s not too accurate). So if you do a home test, check that as well. Remember also that fully charged on hook up it gives a higher voltage which settles after an hour - so that would be your starting point to monitor drainage, I think.