Leisure Battery Circuit Issues

[Gavinskii]

I have recently returned from a trip down to Croatia where it was hot and we were off the grid using my newly professionally fitted 120w solar panel to keep the 2 leisure batteries topped up.

However even though it was wall to wall sunshine and we were really only running the fridge 24/7 + 5c I found at times the fridge would switch off due to lack of power.

I told myself that the Cali (now 10years old) was probably just in need of Leisure battery refreshment. I bought 2 x new upgraded 100w batteries (the ones I took out looked very recent so I don't think in hindsight they were shot), charged them on the hook up cable for 24 hours then drove 40 miles to my UK destination and just utilised the fridge on similar settings last weekend. The result was that by the evening the control panel was telling me that I was down to 70% - which considering it was sunny and the solar was running with no indicated faults on the separate panel - is really poor.

When I changed the leisure batteries I checked the big fuse on the rear battery and it was fine, so I am hopeful that the 2 batteries are working together.

Having owned this Cali for more than a year, it has not exhibited any other issues which would make me think there is an earth shunt issue - or would I not notice?

I would be grateful for any pointers of things I haven't checked

 

[panadero]

We have two solarpanels on our Cali and a little experience now. Don't depend on the (calculated) % value on the controlpanel but read the voltage on that display. That is the right indication what's left in your two household batteries. During a 10 day sunny stay on a campsite, just the solar panels where enough to keep the batteries ok and the beers cold.

 

[Gavinskii]

It's dropping to 12.7 and 70% according to the central control panel....

 

[panadero]

Important is also the charge regulator, a small box between the panels and your batteries and managing the loadingcycle's. Check if everthing is ok on that. After some investigation a switch was in the wrong position (acid/gel) on ours.

 

[WelshGas]

It's dropping to 12.7 and 70% according to the central control panel....

Is that 12.7v in full sunlight? On my system I get at least 13.9 v showing in full sunlight.

 

[Gavinskii]

Important is also the charge regulator, a small box between the panels and your batteries and managing the loadingcycle's. Check if everthing is ok on that. After some investigation a switch was in the wrong position (acid/gel) on ours.

Ok, I would like to check this, could you describe where I find it?

 

[Gavinskii]

Ye

Is that 12.7v in full sunlight? On my system I get at least 13.9 v showing in full sunlight.

Is that 12.7v in full sunlight? On my system I get at least 13.9 v showing in full sunlight.

Yes that is correct ( with fridge on). With fridge off, it will quickly restore up to 100%.

 

[Hotel California]

Ok, I would like to check this, could you describe where I find it?

https://vwcaliforniaclub.com/threads/location-of-inverter.11325/#post-107628


On recent models the location is on top of the rear lesure battery acces thru the hatch in the booth....
Half way down page on in this topic you can see how it looks
https://vwcaliforniaclub.com/threads/cali-technical-tips-tricks.9457/

 

[Borris]

We have been away in our SE for the last few days. When leaving a campsite I always check the charge level. On one of these recent checks I noticed that the leisure battery charge on the overhead control panel was only reading 70 %. This is the lowest it has ever registered despite us having been on a hook up all night. Now this isn't the first time that it has shown a lowish reading when first checked even though we hadn't been drawing much power, just fridge and lights. However as with previous occasions, I merely turned off the control panel and after a few seconds switched it back on and hey presto, it had risen to 80%. A third attempt showed a full 100% charge!

Now I confess that I have never really had any interest in automotive electrics, leaving anything of that nature to those who are qualified, therefore I don't pretend to understand why this happens. However it seems to me, a mere pleb, that the system takes a while to adjust to the correct setting. If I am correct then should owners not to accept the first reading and try again using the above mentioned proceedure? If I am wrong then why is it the control panel not giving a consistent reading?

I should add that our van is a late 2015 T5 with 6000 miles on the clock and I have always given it a regular monthly 24 hour charge. When not in use I turn the contol panel off to reduce battery drain.

Can anyone shed any light on this issue please?

 

[snowy55]

Do you know which type of controller you have?
Is it the PWM or the SMMT unit, is this the "problem"?

 

[Borris]

Do you know which type of controller you have?
Is it the PWM or the SMMT unit, is this the "problem"?

Hello Ian,
Is your post in reply to my previous post? If it is then I am sorry but I don't fully understand your question. If it isn't then please excuse me as I am just being dense.
By controller I assume you mean the over head control panel? If that is the case then I wasn't aware that there are two types.on the SE.
I fear your comments were in reply to someone else and I have just been a prize plum.

 

[WelshGas]

Ye


Yes that is correct ( with fridge on). With fridge off, it will quickly restore up to 100%.

At present I have 13.5v showing with fridge on Level 5 in full sunlight. Also charging 2 phones an iPad and Kindle.
Just spent 4 days in Florence. The van was parked up. Fridge on Level 5 and Solar Panel kept Leisure Batteries at 100%
I think you could have a problem.
Panel, Solar panel control unit or wiring. I think you should have more than 12.7v showing on the vehicle control panel.

 

[snowy55]

Hello Ian,
Is your post in reply to my previous post? If it is then I am sorry but I don't fully understand your question. If it isn't then please excuse me as I am just being dense.
By controller I assume you mean the over head control panel? If that is the case then I wasn't aware that there are two types.on the SE.
I fear your comments were in reply to someone else and I have just been a prize plum.

Sorry Borris , it's in answer to the original post.

 

[snowy55]

Do you know which type of controller you have?
Is it the PWM or the SMMT unit, is this the "problem"?

I'm talking about the solar panel control panel, that was fitted at the same time as the solar panels, not the display unit above the rear view mirror or the inverter / charger that I think on a 2006 is fitted underneath the fridge.

 

[Borris]

I'm talking about the solar panel control panel, that was fitted at the same time as the solar panels, not the display unit above the rear view mirror or the inverter / charger that I think on a 2006 is fitted underneath the fridge.

Yes, its just me being a plonker. Having re-read the original post I realise that it was really about solar panels. That will teach me not to read it through thoroughly.

 

[panadero]

Ok, I would like to check this, could you describe where I find it?

Near the main switches, above the gasbottle....

 

[panadero]

Found also out that it's possible to connect a small information panel to this charge regulator. Buyed on E-bay and shows the actual produced Volts and Ampere's. Nice to see what's happening on the roof...

 

[snowy55]

Near the main switches, above the gasbottle....

View attachment 15603

The location and manufacturer of this unit depends on who fitted the solar system.

 

[Gavinskii]

Just back from another excellent weekend away in the Cali. To clarify I don't think this is an issue with the solar panel which was supplied and professionally fitted by Roger of Solar Camper Solutions, who I know has done many installations for people on this forum. I have the more sophisticated MPPT controller and also an additional remote display so I can see that it is charging properly.

I believe the problem must be a a broken connection between the 2 leisure batteries, though I can't seem to figure out where.

Thanks to Panadero for a photo of the location of the dip switches, I will take a look at these tomorrow and report back.

 

[Roger Donoghue]

The battery graphic symbol with the bars in it is quite misleading. This is because you can’t tell if a battery is full or empty when it is under load (being used), or , being charged. (btw - your panel is 100W, not 120)

A full battery rests at 12.6 volts. This is at “rest” – i.e. not being charged, nor being used. Basically, disconnected. It is flat when it is at 11.9 volts

The moment you start charging it (i.e. solar charging, or split relay charging with the engine running) it’s impossible to tell it’s state as the charging raises the voltage of the battery, masking it’s true state of charge. The same is true when you use the battery (put it under load). As soon as you start using the battery its voltage will drop. You could use this new voltage to ascertain how full/empty it is, but, you’d be wrong as as soon as you switched off the load, the battery voltage climbs back up a fair bit.

As you can see , it’s hard to know the battery level when in use/being charged. The battery might be nearly full, but your fridge drags it down to 12.24 volts – which you’d think is half empty, but when you switch the fridge off, it climbs back up to 12.45 volts (75% full). Similarly, it might be sunny, which lifts the voltage high as the solar is doing its trick, but when the sun goes in, the voltage drops a bit.

With not much load, and some decent sun, the battery will eventually show as full because it will have climbed to 14.4 volts. The charger thinks 11.8 volts is empty (correct) and that 13.8 volts is full (incorrect – it’s true when being charged, but not when it isn’t being charged – batteries are charged to over 14 volts as part of the charging process). This is why the battery icon is misleading.

The best way to get an idea of the battery capacity is to look at the voltage, not the icon. Switch as many thirsty things off, like your fridge etc. and look at the voltage. This will only work at dusk/night/in grey weather as the solar charging during the day will skew the figures. As a good guideline:


12.60v . . . . . . . . . . 100%
12.45v . . . . . . . . . . 75%
12.24v . . . . . . . . . . 50%
12.06v . . . . . . . . . . 25%
11.89v . . . . . . . . . . 0%


It is not unusual to see your battery drop to the low 12’s at night when the fridge is running, with no sun, then recover to over 13v in the morning as the sun comes up. How fast it drops at night depends on the capacity and age of your leisure battery. As a guide, a new 100Ah battery will run a compressor fridge for around 2 to 3 days with no charging help.

 

[Roger Donoghue]

We have been away in our SE for the last few days. When leaving a campsite I always check the charge level. On one of these recent checks I noticed that the leisure battery charge on the overhead control panel was only reading 70 %. This is the lowest it has ever registered despite us having been on a hook up all night. Now this isn't the first time that it has shown a lowish reading when first checked even though we hadn't been drawing much power, just fridge and lights. However as with previous occasions, I merely turned off the control panel and after a few seconds switched it back on and hey presto, it had risen to 80%. A third attempt showed a full 100% charge!

N

I had a customer ask me about this recently. The overhead control panel was showing that his leisure battery was at a low %, yet the solar regualtor, and a multimeter both showed that battery to be near full. I dont' have deep knowledge of how the VW charging system works, but the only thing I could think of was that the VW system was tracking charging current, and as the charging from the solar doesn't go "through" the VW system that is was assuming the battery was low (as it can see the load current, but not the solar charging current). It's an odd way to calculate battery capacity, but so is the method the solar regulator uses!

 

[Gavinskii]

Roger, thanks for chiming in so quickly.
I guess the reason I think I have a fault on my Cali (not with the Solar set up), is that when I was away and the fridge was working really hard (@7c) but in 35 degree heat day in day out and by the evening I had the the following message showing on the remote display.


This led me to believe that my 2 x 75W leisure batteries must be shot, however having ordered up the 2 x 100W replacments, it was apparent that the 75W batteries were in facrt virtually new. Does this help in anyway to explain what the issues are?

 

[Roger Donoghue]

If that's the evening, you had very bright evenings!

The display is showing you are getting a charging current of 3.9 amps, which in 35 degree heat is about what I'd expect from a 100w panel (more like 5 amps in UK tremperatures). Or what I'd expect on a bright evening abroad when the sun was still up high.

At those kinds of temperatures your fridge is probably on 2/3rd of the time, rather than the usual 1/3rd of the time. The power draw is drastically affected.

Looking at that display - I would assume the fridge is actually running at that time (i.e. compressor running) - as I'd expect the voltage to climb quite quickly when the fridge shuts down. 3.9 (solar) amps into the battery(s) would make the voltage climb fast. 3.9 amps when the fridge is actually running would leave the battery as-is - you'd be providing pretty much the same power as the fridge consumes.

I'm suspecting you may have been simply victim to the heat - which makes the fridge work doubly hard.

The only way to really know is to see how it recharges in normal weather, then switch the fridge on, put an ice cube in the freezer, and check in every so often and see how long the fridge can go before the ice cube melts. With 200Ah of batteries you really should see over 4 days of fridge running without any help at all. Bear in mind where you set the thermostat and how hot the weather is has a big effect.

You certainly seem to be getting plenty of solar help. I've not yet seen a charger say it is charging when it actually isnt.

 

[Gavinskii]

I've just been out to the Cali which has been parked on my driveway in UK all day. I guess it's been circa 20c today and fairly cloudy. I've left the fridge on @7c since I returned yesterday evening, and just checked the MPPT remote display and the central VW panel - I attach the photos taken 10mins ago.
What do you make of that (the fridge compressor was not on when I took pictures - as can be seen from the zero amp draw on the central display).
Should these 200amp brand new leisure batteries drop to that level (70%) so quickly?

 

[Roger Donoghue]

10 minutes ago was at 8:30pm. No solar energy.

12.5 volts is 0.1 volts from full for a leisure battery at rest.

Your battery is 99% full. The fact that the VW panel says 75% is not true. 12.5 volts is small a fraction off full.

As I said above, I don't know how the VW panel calculates "full", but I can tell you with 100% certainty, 12.5 volts is as near to full as possible without being 12.6 volts. I imagine the VW system sees 13.8v as "full" - which is true, but only under charge.

You have had your fridge running all day and more, and your battery is full at 8:30pm in the evening. Which seems ideal.

You have emailed me regarding the AGM batteries. AGM batteries are charged with the same profile as "sealed" lead acid batteries. You can also use the "gel" profile as this is the same, except it skips the equalisation charging phase.