Blue Motion Charging Hack

[TIPI]

Hi People,
New member here,
I've had my t6 2 years now and have odd issues with battery going flat over a few months of short journeys etc so I wonder if you could just disconnect sensor on the neg post of battery so alternator charges battery all the time? I've had battery and van checked and all is working as it should , I'm just thinking if I disconnect this sensor the battery will charge above 80 % and be more user friendly on short journeys during winter months and also mean I can swap battery without having to recode new one to ecu?

thanks in advance

 

[Pete C]

What make of battery do you have ?
There is a known issue with Moll batteries failing.

Pete

 

[TIPI]

What make of battery do you have ?
There is a known issue with Moll batteries failing.

Pete

Cheers Pete, we have Vatra and vw have had van back and found no issues, my initial test showed it was low on amps after it had been on a run but I charged it on a full ctek charge cycle the past week its been sat on driveway and battery showing 12.5 v which is ok , not perfect but ok. looking back we had hardly used the van in nov and dec apart from short journeys and just realised that my wife opens and closes the van every time she goes out to it when loading it ...so this could be done 4 or five times when taking Grandson home , so lights come on every time and doors opened and shut etc all draining battery esp when she then only does 2 miles to my daughters and the process is repeated. van now relegated to camper only and left on hookup and its beed fine...
just wondering if you can cheat the blue notion thing by disconnecting sensor

 

[Dellmassive]

Disconnecting the battery sensor will make the alternator output a straight 14.8v ish..... not sure if there is any voltage regulation passed that?

Its unknown of the effects of long term running like that..... over charge battery possibly?

Obviously it would disable stop start etc.

Though it is a known BMW hack on older models to temporarily dissbale stop.start.

Let see if anyone else has done the same for any duration.

 

[Salty Spuds]

Cheers Pete, we have Vatra and vw have had van back and found no issues, my initial test showed it was low on amps after it had been on a run but I charged it on a full ctek charge cycle the past week its been sat on driveway and battery showing 12.5 v which is ok , not perfect but ok. looking back we had hardly used the van in nov and dec apart from short journeys and just realised that my wife opens and closes the van every time she goes out to it when loading it ...so this could be done 4 or five times when taking Grandson home , so lights come on every time and doors opened and shut etc all draining battery esp when she then only does 2 miles to my daughters and the process is repeated. van now relegated to camper only and left on hookup and its beed fine...
just wondering if you can cheat the blue notion thing by disconnecting sensor

I would’ve thought that disconnecting the sensor/hacking the blue motion would have zero affect in this case. If the battery is low, the system will charge it anyway regardless. The system will be putting as much charge as it can into the battery in the short time the engine is running. The problem here is you’re taking more out than the van has chance to replace.
IMO

 

[Pete C]

I would’ve thought that disconnecting the sensor/hacking the blue motion would have zero affect in this case. If the battery is low, the system will charge it anyway regardless. The system will be putting as much charge as it can into the battery whilst the engine is running. The problem here is you’re taking more out than the van has chance to replace.
IMO

I was about to say something very similar (honest !).

Pete

 

[Pete C]

There is a really simple way to tell when your smart charging vehicle has decided that there is enough charge in the battery.

Buy yourself one of those cheap car USB chargers that plug into the cigar lighter socket, but get one that has a voltage display.
Make sure you can easily see it when driving, and check the voltage when you are driving. When it's charging, the voltage will be 14.5V or thereabouts.
When it has decided you have enough charge, it will drop to 13.5V or so when you accelerating, but rise to 14.5v on overrun.

I suspect that on your short journeys it will show 14.5V all the time, meaning that the hack described wouldn't actually help.

Pete

 

[TIPI]

There is a really simple way to tell when your smart charging vehicle has decided that there is enough charge in the battery.

Buy yourself one of those cheap car USB chargers that plug into the cigar lighter socket, but get one that has a voltage display.
Make sure you can easily see it when driving, and check the voltage when you are driving. When it's charging, the voltage will be 14.5V or thereabouts.
When it has decided you have enough charge, it will drop to 13.5V or so when you accelerating, but rise to 14.5v on overrun.

I suspect that on your short journeys it will show 14.5V all the time, meaning that the hack described wouldn't actually help.

Pete

I've bought a volt meter for cigar socket and as battery is currently 80% it rarely charges so sits at 12.2 -12.4 volts and only charges when needs it mostly on deceleration, braking etc or when heated
seats and heater blower put above 2.... I will keep eye on things easier now , I'm used to driving a Landrover and have never had issue with flat batteries but I do have a larger battery and they are charged to 100%
not kept at 80% so are capable of more abuse I guess.

 

[TIPI]

I would’ve thought that disconnecting the sensor/hacking the blue motion would have zero affect in this case. If the battery is low, the system will charge it anyway regardless. The system will be putting as much charge as it can into the battery in the short time the engine is running. The problem here is you’re taking more out than the van has chance to replace.
IMO

this is one of the reasons for wanting to upgrade the battery

 

[JasonW]

What is the recommended battery to upgrade to..?

 

[TIPI]

What is the recommended battery to upgrade to..?

not sure , hoping a few experts will advise , ill prob just swap my standard 68amp 680 cca for a bosch 80 amp 800cca

 

[Salty Spuds]

not sure , hoping a few experts will advise , ill prob just swap my standard 68amp 680 cca for a bosch 80 amp 800cca

But unless you start & replace the amps that you’re drawing from the battery, either by longer runs or using a charger, you will be in the same position. You’ll just have a larger flat battery.

 

[TIPI]

But unless you start & replace the amps that you’re drawing from the battery, either by longer runs or using a charger, you will be in the same position. You’ll just have a larger flat battery.

yep , I realise this .... but a larger battery will cope with the shorter journeys and door opening and closing etc during winter, that's my thinking. esp knowing now that a blue motion system only allows battery to be 80% charged so seems a good idea

 

[Salty Spuds]

yep , I realise this .... but a larger battery will cope with the shorter journeys and door opening and closing etc during winter, that's my thinking. esp knowing now that a blue motion system only allows battery to be 80% charged so seems a good idea

But a bigger battery will also take longer to charge. Bear in mind that once a lead acid battery gets down to 45-50% charge, the voltage drops to a point where it won’t start the vehicle. So a short run with a small battery will get the battery to a higher state of charge (SOC) & hence the voltage will be higher after the short run. The same run will bring a larger battery to a lower SOC.
Your call, but unless you resolve the fundamental problem of not replacing the amps used, then you’re no better off.
IMO

 

[TIPI]

But a bigger battery will also take longer to charge. Bear in mind that once a lead acid battery gets down to 45-50% charge, the voltage drops to a point where it won’t start the vehicle. So a short run with a small battery will get the battery to a higher state of charge (SOC) & hence the voltage will be higher after the short run. The same run will bring a larger battery to a lower SOC.
Your call, but unless you resolve the fundamental problem of not replacing the amps used, then you’re no better off.
IMO

what are my options ?
I have two Landrovers with larger batteries , one with dc-dc and one with matched agm and solenoid split charge, both draw lots of amps and both can be used for short journeys and can be left for two weeks with no issues .
I have never had an issue with these and that’s with standard alternator .

Am I asking too much from the newer charging system , or is the issue with the wife opening and shutting the doors 5 times .... could get shot of the wife I guess

 

[Long tall John]

Would led interior lights make much of a difference? I doubt it but some clever clogs on here will know! Maybe led drl's?

 

[keith baker]

I disconnected mine for a few months last year. From memory I think it charged at about 13.2V although that was measured by a dubious cigar socket volt meter. I reconnected it as I thought the leisure battery would charge better if the alternator was charging at 14.5V. I believe the DC/DC charger will 'hold' the smart alternator at a higher voltage. I now plug in a ctek charger if the van is idle for more than a few days.
Don't take my word on the facts of this as I could be talking a load of bo££0cks. Just that it did no real harm to the van.
Easiest is to check it yourself.

 

[Shaun Witts]

Is it not common to disconnect this lead from the battery for the sole purpose of disabling stop/start?

That’s what I’ve done. Reason being mainly because my TSI has an LPG conversion, which always starts on petrol before switching to LPG. So stop/start uses more expensive petrol rather than the cheaper LPG.

I’ve not noticed any side effects of this yet.

 

[Grim Reaper]

Does the van keep the battery at 80% even if the stop start is manually disabled via the button?
I have noticed that if I charge the battery with my CTEK externally (no need to open van doors) then it keeps a good charge (green light as interpreted via the CTEK comfort indicator I connect the charger up to) for over a week.
I have a stop/start defeat device fitted that automatically turns the stop start off so it never gets left active.
If I use the van it drops to an orange light after 2 or 3 days which suggests to me that the van still keeps the battery at 80% even if stop start is deactivated.
I have thought about changing the battery settings in the ECU via VCDS to up the capacity rating from its current 95Ah (Bosch S5 A13 95Ah 850CCA AGM - The largest I could fit into the original battery tray) to 115Ah so an 80% charge would be around the 95Ah level?? Does this make any sense?