Leisure batteries question

[Glenhyrst]

I have a 4 month old Westfalia Club Joker with x 2 leisure batteries as per Westfalia spec ie 1 x 70Ah and the additional one at 100Ah.
When using habitation electrics, only the former shows any drop in voltage eg from 12.4v to 11.4v whilst the latter stays at 12.6v.
I expected that batteries wired in parallel would drop voltages equally.
Might there be some complex management system that drains one battery significantly before engaging its fellow? And if so, why?
And a second question, whilst on EHU or with the engine running, should both batteries show a charging voltage? In my case, only the 70Ah battery does.
It's been back to the supplier three times and comes back just the same.
What am I missing?

 

[Deaky]

I'm not familiar with a club joker set up but I cant understand why a 70ah and 100ah batteries would be connected in parallel. Can you attach some photo's of the batteries?

 

[CAB]

Are you sure the 70aH doesn't refer to the vehicle (starter) battery?

It would make sense from your quoted voltages.


EDIT: The Westfalia website currently says "Battery 95aH" which would confirm this.

So, the real question is why your leisure battery is dropping to 11.4v, and why it isn't charging from EHU and when driving.

How do you measure the voltage at the battery? Is it on a control panel?

EDIT 2: And welcome to the forum!

 

[Glenhyrst]

Are you sure the 70aH doesn't refer to the vehicle (starter) battery?

It would make sense from your quoted voltages.


EDIT: The Westfalia website currently says "Battery 95aH" which would confirm this.

So, the real question is why your leisure battery is dropping to 11.4v, and why it isn't charging from EHU and when driving.

How do you measure the voltage at the battery? Is it on a control panel?

EDIT 2: And welcome to the forum!

The starter battery is indeed 70Ah but the leisure batteries are the ones in question - see below* with the amendment that one of mind is 70and not 75Ah.
But regardless of size, have I a problem here? When the supplier has had 3 goes at a fix and tells me all is well, is what I describe above as it should be and why? Why run one battery down at the expense of another? At this rate, if I only used the vehicle on sites with EHU, come the day when the 70Ah dies, I will have to dispose of a perfectly good 95Ah battery to satisfy the dictum that in this situation, both batteries should be identical in all respects. Apart from what Westfalia install it seems.

*The standard leisure battery is 75 Ah AGM and the additional is 95 Ah AGM.

Mit freundlichen Grüßen / with kind regards
Westfalia Mobil GmbH

 

[CAB]

The starter battery is indeed 70Ah but the leisure batteries are the ones in question - see below* with the amendment that one of mind is 70and not 75Ah.
But regardless of size, have I a problem here? When the supplier has had 3 goes at a fix and tells me all is well, is what I describe above as it should be and why? Why run one battery down at the expense of another? At this rate, if I only used the vehicle on sites with EHU, come the day when the 70Ah dies, I will have to dispose of a perfectly good 95Ah battery to satisfy the dictum that in this situation, both batteries should be identical in all respects. Apart from what Westfalia install it seems.

*The standard leisure battery is 75 Ah AGM and the additional is 95 Ah AGM.

Mit freundlichen Grüßen / with kind regards
Westfalia Mobil GmbH

Have you seen both batteries? Are you sure that 'additional' isn't a mistranslated 'option'?

It seems very odd to use two different size leisure batteries, normally the advice is to use identical.

Do you have pictures of the batteries / and the voltages?

 

[Glenhyrst]

Have you seen both batteries? Are you sure that 'additional' isn't a mistranslated 'option'?

It seems very odd to use two different size leisure batteries, normally the advice is to use identical.

Do you have pictures of the batteries / and the voltages?

It may seem odd to fit different sized ie Ah batteries but that's what Westfalia do if you go for the additional ie optional addtional battery. "Experts" produced by a Google search do seem to differ in their seemingly firm opinions as to whether batteries in parallel must be identical in every way. But which of them is right?
Of course I have seen them - in fact, I'm sick of them. Can't think of a reason I would make this up. And I can read my multimeter too. Not sure what pictures would add to the answer to my question?

 

[Pete C]

Yes, definitely need pictures of the wiring and controllers and batteries.

Pete

 

[jimc91]

You will be amazed how the folks on here can help when they see pictures, you've asked a perfectly understandable question but to get an answer others have asked for pictures of your two batteries and the voltages you are seeing - not that difficult really

 

[CAB]

Ok, so:

- you have two leisure batteries of different sizes;
- one is being discharged but not the other;
- the one that is NOT discharged is the one that gest charged up by EHU + driving.

If that is the case, clearly they are not connected in parallel. Can you see the wiring on them? Something is not right. Have you checked the connections? Checked the resistance along the connections?

 

[CAB]

Just to say, I can only recall one user a few years ago with a Westfalia, there may be more but not common on this forum.

Just to explain that there may not be anyone on here with the identical setup, but plenty of experienced users and installers.

 

[Glenhyrst]

Yes, definitely need pictures of the wiring and controllers and batteries.

Pete

I've got you. Unfortunately all that can be pictured are the backs and part of the tops of the batteries that are buried, along with all the bits and pieces, under the front seats.
I am reluctant to remove the seats as I have no idea how difficult this might be and would not wish to make a hash of this and risk warranty issues that may arise in the future with VW who, from may reports I have read, do not hesitate to avoid warranty repairs if they can.
Are circumstances in which what I observe in the batteries behaviour is as was designed? And if so, why?
Whilst the perfect response might be "This is what's wrong and this is what to do to fix it", what I'm really after is the answer to the question "is this right or wrong?".
I think the latter. The van supplier so far disagrees. We can't both be right.
Phil

 

[Glenhyrst]

Ok, so:

- you have two leisure batteries of different sizes;
- one is being discharged but not the other;
- the one that is NOT discharged is the one that gest charged up by EHU + driving.

If that is the case, clearly they are not connected in parallel. Can you see the wiring on them? Something is not right. Have you checked the connections? Checked the resistance along the connections?

Firstly, my apologies to those who have asked for pics and my seemingly unwilling to send them. Apart from access to the backs of the batteries and the the ability to put a probe on the terminals, everything else is buried under the two front seats and without removing them, no pic of any use can be obtained.

To the above, yes, 2 different Ah 12v otherwise identical AGM batteries but only the one that discharges receives a charging voltage on EHU and driving.

Interestingly, the technician at the supplier felt that my observatons were not valid as there was some clever charging/management kit involved (?)
As to resistance, I don't think the readings I get are correct. There is continuity between both +ve poles but not between both -ve poles (or rather a reading that fluctuates unsteadily) and continuity between the 70Ah +ve and the 95Ah -ve. There is no continuity between the 70Ah +ve and 95Ah -ve.
These suggest a problem to me but I have made 3 round trips of 80miles to the dealers over the batteries issue and before taking it further, I'm trying to be certain that all is not well - it's getting to be a very frustrating business!

Phil

 

[Pete C]

You are correct, there must be something additional between the 2 batteries as otherwise they would show the same voltage. They clearly aren't truly in parallel, but without the manufacturer telling you more, or someone dismantling what you have, you aren't going to get an answer.
Is there a local auto electrician locally ?

Pete

 

[Glenhyrst]

You are correct, there must be something additional between the 2 batteries as otherwise they would show the same voltage. They clearly aren't truly in parallel, but without the manufacturer telling you more, or someone dismantling what you have, you aren't going to get an answer.
Is there a local auto electrician locally ?

Pete

The van being bought new has a warranty that states that work must be done by a Westfalia dealer. One is 40miles away near Hull and the others on the South Coast. It has 20 months of warranty cover remaining, so at the moment I'm disinclined to get the work done by an auto electrician although it may come to that. But the alternative, based on my experience thus far, is to keep going back to be told the work has been done, only to find this appears to me not to be the case.
It could provide a script for a John Cleese comedy and could run into many episodes.

Phil

 

[oldiebut goodie]

As to resistance, I don't think the readings I get are correct. There is continuity between both +ve poles but not between both -ve poles (or rather a reading that fluctuates unsteadily) and continuity between the 70Ah +ve and the 95Ah -ve. There is no continuity between the 70Ah +ve and 95Ah -ve.
These suggest a problem to me but I have made 3 round trips of 80miles to the dealers over the batteries issue and before taking it further, I'm trying to be certain that all is not well - it's getting to be a very frustrating business!

Phil

To me that reads like a dodgy earth/negative connection on the 70Ah battery.

 

[Pete C]

Have any conversations with the dealers intimated that there is some sort of additional charging mechanism between the 2 batteries ?

Pete

 

[Glenhyrst]

Have any conversations with the dealers intimated that there is some sort of additional charging mechanism between the 2 batteries ?

Pete

No, apart from a vague reference to the presence of an "intelligent charger". But even if there were such a thing, what would be the purpose of exploiting just 1 battery when 2 are present? Is there available some sort of mechanism that would be designed to produce the effects I find and again, if so, why? Why not just a straightforward parallel link and have done with it? But lest you have not guessed, my knowledge of electronics is limited!

Phil

 

[Glenhyrst]

I have a 4 month old Westfalia Club Joker with x 2 leisure batteries as per Westfalia spec ie 1 x 70Ah and the additional one at 100Ah.
When using habitation electrics, only the former shows any drop in voltage eg from 12.4v to 11.4v whilst the latter stays at 12.6v.

It's been a long haul but at last both leisure batteries are working in parallel.
The resolution came when 80amp fuses were found to have blown. First one was replaced on the 70Ah battery which altered nothing. A bit odd because that battery was the only one performing before that fuse was changed! But it was only subsequent to that when my persistence eventually had the 95Ah battery's fuse discovered to be at fault.

I feel a little uneasy at such fuses blowing but I guess it's a case of wait and see.

I had an issue with the stop/start never having worked but this has finally been resolved when a lead to the positive battery terminal was found hanging in the breeze and reattached. The suspicion is that it was not replaced after being removed to fit terminals relating to the fitting of the towbar electrics.

 

[roadtripper]

Like others I'm very surprised at a bank being created from different batteries, that's asking for trouble. A bank should be formed from identical batteries of matched capacity and they should be in a bank from new so they form with each other.

The classic issue with a bank is that as one battery ages it will parasitically discharge the good one because it's voltage will drop. And a classic sign of that is when it reaches a really bad state the current is enough to blow the battery fuses (if individually fused) or the bad battery just drags the others with it in rapid ageing (if not)

If you form a higher capacity battery by using a bank one of the downsides is as soon as one battery shows signs of aging you need to condem them all. We have this issue on the narrowboat on our house bank with 4x110ah batteries. The other owners ignored my advice and just replaced the bad one, which was then dragged down by the 3 older ones until one of them went, and we ended up replacing all remaining 3 as individual call out emergencies in the next year. And then the unequal aged bank only lasted another year and a bit. Replaced properly that time with a battery monitor we now get 3 years out of a bank (they are worked hard almost every week of the year as the boat is always out somewhere)

 

[Glenhyrst]

Like others I'm very surprised at a bank being created from different batteries, that's asking for trouble.

The problem is that Westfalia fit them thus - 1x75Ah as standard (although the one in mine is 70Ah) and if a second leisure battery is requested, it is a 95Ah battery that is fitted.
Apparently with all the wiring and associated electrical gizmos tucked under the seat with the smaller battery, there is no room to fit a 95Ah battery. They presumably have confidence in this otherwise one might have expected them to fit 2 x 75Ah batteries. Good luck with getting answers from them on this!
Both are new and of the same make. And given that the 95Ah battery was never on-stream from the day I got the van (new), there seems no way it could have affected or been affected by the 70Ah battery.
Some folk online seem of the opinion that if 2 batteries are connected in parallel that provided they are of the same age, make and voltage then diferent capacities do not matter. However, that it is not a good idea seems prevalent. I'm at the learning stage and do not know which is true and which is urban myth although I can easily see that the case you quote of mismatched batteries in terms of age and use is likely to cause trouble for the reasons you mention.
The 95Ah battery never showed any drop in voltage at all - unlike the starter battery which seems to lose voltage rather quickly. Something I will explore further.
And can you explain why when on EHU, the starter battery is not charged? Seems nuts to me.