Solar and regen charging ?!

[Floor Fit]

Has anyone running solar had a problem with overcharging when the van is running ? mine charges averagely at 13v - 5 amp during the day , i leave the fridge on constantly and two gas detectors .
When i drive the van and it goes into regen charging the gas alarm on the back of the seat base next to the 110ah AGM battery goes off ( factory wired aux battery ) this also has a vent and the vw factory hood over it, so must be a bit of gas about , if it wasn't for the gas alarm i would have no idea it was doing it.

I understand how the van charging system works and that it bulk charges etc etc so what is the solution when you have a van set up as a camper ? obviously the aim is to keep charge in the battery but the van system needs enough room ( 20%) for it to bulk charge, is there a solution ??
Picture from first install so battery not yet full .

 

[T6 Dave]

The solar should only be charging the Leisure battery, and not the vans Battery, this way you have the 20% top up room needed for the smart charge..

the solar should stop charging when the batt is full, or the vans electrics kick a higher charge, then the solar kicks in again when it is needed..

the problem is that you have a bcm controlled split charge unit, and this will give a hiccup.. by back feeding the higher charge into the headspace of the main battery, without the solar connected, both batteries will only attain 80% of charge using the factory system..

 

[Floor Fit]

The solar should only be charging the Leisure battery, and not the vans Battery, this way you have the 20% top up room needed for the smart charge..

the solar should stop charging when the batt is full, or the vans electrics kick a higher charge, then the solar kicks in again when it is needed..

the problem is that you have a bcm controlled split charge unit, and this will give a hiccup.. by back feeding the higher charge into the headspace of the main battery, without the solar connected, both batteries will only attain 80% of charge using the factory system..

The solar is only connected to the leisure battery and is separated from the starter battery but the way vw wire it the aux battery gets the same burst charge as the starter - maybe all of our batteries are giving off loads of gas and its only because i have a gas monitor next to mine i know its over charging ??!!

 

[Floor Fit]

sorry just re read T6 Dave .. the starter battery has space in it according to the smart meter but the leisure battery is full , the only issue i have is with the leisure side over charging once the van is started, the solar is doing its job and keeping the battery brimmed ... not a problem i thought i would have with just a 120w panel

 

[T6 Dave]

OK, solution that you won't like, is to run the vw feed into a unit such as the ctek or ring unit, as that will refuse to charge the leisure from car system if it is full..

 

[Loz]

As @T6 Dave says but you could also change to an AGM battery that won't gass and designed to work with regen systems.

 

[T6 Dave]

Yeah, but the battery life will still be reduced due to overcharging.. The bcm connects the leisure to car system when car is turned on.. This then charges a full battery every time the smart system tells it to charge the van battery, as it appears to be a bcm controlled vsr type.. It also means that the charge flows backward from the leisure battery to the vehicles..

This has been shown in the Cali cars via their bat monitor.. Vw don't expect you to throw a spanner in the works by wanting your leisure bat to be over 80% charged..

The ring unit will sleep when the leisure bat is full.. Thus disconnecting it from the system so the overcharge can't occur..

Hope that makes sense, not quite with it at the moment...

 

[Floor Fit]

As @T6 Dave says but you could also change to an AGM battery that won't gass and designed to work with regen systems.

Thats the thing it is a AGM

 

[T6 Dave]

you mean agm, not a mercedes.. Just leg pull

 

[Floor Fit]

OK, solution that you won't like, is to run the vw feed into a unit such as the ctek or ring unit, as that will refuse to charge the leisure from car system if it is full..

No that sounds great - i wired the thing im sure i can put a unit in line with it - just means separating the van supply ? which unit do you suggest ?

 

[T6 Dave]

What you have to realise is that the bcm unit does not sense the leisure bat state of charge, and shut off sharing when full, instead it connects them together and treats them as one..

 

[Floor Fit]

you mean agm, not a mercedes.. Just leg pull

sorry updated that typo

 

[T6 Dave]

Personally, for the cost, and the fact it tells you what its doing, I'd look at the ring DC to DC 30 amp unit.. Only thing is its got solar in with it..

 

[Floor Fit]

What you have to realise is that the bsm unit does not sense the leisure bat state of charge, and shut off sharing when full, instead it connects them together and treats then as one..

i can see that being the problem - whats the best route ?

 

[Floor Fit]

Personally, for the cost, and the fact it tells you what its doing, I'd look at the ring DC to DC 30 amp unit.. Only thing is its got solar in with it..

can i install it inline with the vans feed so in crude terms isolating the split charge part of the system stopping the alternator from charging the aux battery only leaving he solar and MHU to do its thing independently ? ( yes would be the ideal answer )

 

[T6 Dave]

RSCDC30 | DC/DC Battery SmartCharger | SmartChargePro

The instruction book is on this page as well..

 

[T6 Dave]

can i install it inline with the vans feed so in crude terms isolating the split charge part of the system stopping the alternator from charging the aux battery only leaving he solar and MHU to do its thing independently ? ( yes would be the ideal answer )

As far as I am aware.. Yes, as all the bcm vsr arrangement should do is feed the unit when car turns on, the solar will feed it all the other time, when the car is on and taking feed from there, it will only charge leisure if it needs it, and is able to supply a higher rate than solar.. But not quite with it enough at the moment.. However short answer is that there is a feed in there somewhere that will be suitable.. You need to sort this as its bad for your batteries..

 

[T6 Dave]

Hope this has led you somewhere, I'm not at my best on this at the moment....

 

[Floor Fit]

As far as I am aware.. Yes, as all the bcm vsr arrangement should do is feed the unit when car turns on, the solar will feed it all the other time, when the car is on and taking feed from there, it will only charge leisure if it needs it, and is able to supply a higher rate than solar.. But not quite with it enough at the moment.. However short answer is that there is a feed in there somewhere that will be suitable.. You need to sort this as its bad for your batteries..

Thanks @T6 Dave big thumbs up !! im sure the battery will be fubared unless i do something, really appreciate your help

 

[T6 Dave]

BTW, when you wired it, did you connect a battery vent tube to a port on battery and out to external atmosphere, as this will exit gasses clear of living space and hopefully shut the gas alarm up..