Max Charge Button on Dash

[coachella]

Hi all,

So i have an issue with my Knaus Boxdrive 600XL. (MAN TGE MY25).
There is a button on the dash that both the motorhome dealer and MAN service didnt know about.
From investigation it is used when you want the last 20% charged on your starter battery and the 2nd battery (in this case its a leisure battery).
Normal operation is its off (not illuminated) and batteries charge from the alternator to 80%.
When you want the boost - push the button and it illuminates for that extra 20%. The alternator works harder and also when the van is at idle - it revs above the idle speed.
So firstly - anyone knows about this function pls correct me if i am wrong.

The faulty part on this van as i see - the button isnt pressed - but when from idle - the button isnt illuminated. As soon as you set off - the button illuminates.
You press it - and it doesnt turn off.
Come back to a stop and then the button light goes off. Revs are normal not above normal idle.

I have been back to MAN service and they have replaced the BMS for the starter battery. They have looked at it about 6 times now and are saying the starter battery is fine and is blaming the 2nd battery which is a Knaus issue.
I have taken the 2nd battery off and its still the same.

FYI i have replaced the leisure battery for a Lithium and the charger in the back has been switched to allow for that (a brand new dometic charger). Its also part of the blurb saying that the camper comes prep'd for a lithium setup. I also have added a victron smart shunt on that battery to see whats what on the draw when i go to festivals.

I am now coming to 4 months in. And losing the will.
Camper dealer is saying its a base van function - and MAN service is angling towards its a conversion issue. So they are pointing at each other.
I still think there is a major function wrong with that operation of the switch and the BMS in the van part isnt working.
I have also now starting to see when i start up the van , on the dash it says 2nd battery low. And the 2nd battery is 100%.
The Shunt is showing some odd numbers on a drive (watts draw 1.4kW) and 14.4volts - but after 40mins - the van then settles down back to 13volts and a normal draw on watts.

What other things should i check ? Relay ? Replace starter battery ?
I dont think its my lithium since its holding charge and its got its own BMS protecting it.
If the relay - which relay is it going to be - i have no fuse box info.

I just want it to be safe.

Thanks for your inputs.

 

[TonyL]

If you had not changed the battery and changed the settings then the dealer would be on the hook for any issues with batteries going flat.

I assume when you are saying the 2nd battery you mean the leisure battery that you have replaced with a lithium battery?

 

[coachella]

MAN see it as 2nd battery - Camper dealer is seeing as leisure battery. And this was from the day I picked up the new camper. So the dealer is on the hook.
They have been aware from the get go I would put a lithium in - and its only a straight swap. So nothing complicated has been done. Just fitment of battery and setting on the battery charger in the back.
I can put the original back in with no change to how the camper was if needed.

And also both the leisure and starter batteries are good.
Leisure is 100% and the starter has been tested every time its been in with MAN.

 

[mmi]

There is a button on the dash

Share a picture of the button please?

 

[coachella]

 

[Pauly]

But what is the actual problem ?

Other than you not being 100% of the buttons function and not liking the pattern of button illumination is there anything actually wrong ?

 

[coachella]

Sorry - some confusion about the button.

I am not operating the button - it comes on when the camper sets off - drives. When I stop in traffic it goes off.

On my understanding - its a push button (rocker) and should work even at standstill. Tried to explain the function of it above.
So switching it on (pushing the button) it illuminates and is working.
Pushing again switches it off and light goes out.

I am currently not operating the button and its coming on and off on its own - and this is why i am saying this is faulty.

I do know that the Sven Heden has the same button - campervan time have referenced it in one of their overview videos on youtube.

Was just putting this out to the masses to see if anyone has experienced any issues with this ?

 

[G-A-R-Y]

MAN see it as 2nd battery - Camper dealer is seeing as leisure battery. And this was from the day I picked up the new camper. So the dealer is on the hook.
They have been aware from the get go I would put a lithium in - and its only a straight swap. So nothing complicated has been done. Just fitment of battery and setting on the battery charger in the back.
I can put the original back in with no change to how the camper was if needed.

And also both the leisure and starter batteries are good.
Leisure is 100% and the starter has been tested every time its been in with MAN.

I may be able to help you understand further, from my experience with my own Grand California the second battery is the leisure battery too, just different names. You have two matched AGM's. The leisure should be under the bonnet.
The battery/system is a factory fit from VW/Man and used to run accessories on commercial van builds.

There is a simple dumb relay ( on the inner wing) to join both batteries together once the engine is running but this doesn't always happen, it depends on many things like the state of charge as both batteries are only charged to 80% to allow for regenerative braking to take place and others like engine temp and regen status.

Pressing the "boost" button charges both batteries to high voltage but not always as VW Grand California owners often complain about this
You can NOT swap it for a lithium unless you get rid of the dumb relay and replace it with a B2B type. Fitting the Lithium under the bonnet is not great, it gets far to hot and the bms can get damp and corrode. You will have to update your mains charger too.

These are my findings so far. I'm just offering what I have learnt and hope it helps you.

 

[coachella]

Thanks for that Gary. That was my understanding of the 'Boost' button.
So the van is a MY25 (latest) version. In the blurb it comes Lithium ready.
Already has a mains charger with a lithium setting. Also my Lithium has its own BMS to protect it.
I am lead to believe that the van BMS has changed on the MY25 build.

With all the problems i have described above - this was happening with the original AGM in and with the Lithium in that has been swapped.
I have started to think that it could be the van BMS and relay.
I know i am gonna have to go back to MAN to see what they can do.

 

[Wintercamper]

The Westfalia Sved Hedin does not have this button.
It is only assembled in VW Gran California and Knaus Boxdrive.

 

[coachella]

For reference - i have had further discussions with MAN and the dealer/Knaus - and also came across a great document (for a GC600) to explain some of the questions I had.
Finally got a technical answer from Knaus and explaining what they do with the wiring at fitout - and then they have come back with a solution.
So if this referenced here - might come in handy for someone.
I am now waiting for the dealer / Knaus to authorise the works and then will get it booked in at MAN. Hopefully this fixes it.


"
This is what MAN have to say about this charging button:

“This button does not work ex works on any TGE UC type.

The reason for this is that we deliver the TGE with EM-P (energy management parallel), the Grand Cali however is provided with a data set at the factory that enables the button to work on the GC.

The Grand Cali and the TGE UC are manufactured in exactly the same way. However, as the TGE does not receive this data set but is delivered with EM-P, the button does not work, unlike on the GC.

For all UC types MY 24 and <, we have a software solution that is installed on the KFG via a MANTED application so that the charging button works correctly.

For model year 25, we have now received a suitable hardware solution from VW. The TGE UC is still built in virtually the same way as the GC, and the charging button does not work ex works here either.



However, by re-pinning ST3/23 to ST3/25, we can ensure that the charging button functions correctly. This would be the hardware solution that we should definitely prefer to a software solution.

Pins:

MFE_13 (ST3/25) – Charge button (maximum battery charge, controlled by EMP – energy management)

MFA_10 (ST3/32) – Charge button status (PWM for LED)”