Max Charge Button on Dash

coachella

New member
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.
 
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?
 
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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.
 
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 ?
 
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