Battery State of Charge (SOC)

[bgroper]

I gotta add this link to some relevant good-stuff from DV52, so I can find it again later.
SOC Battery | OBDeleven

[DV52]

I cannot access any SOC info from the MFD on my 2017 R either, so it's likely that VW have not enabled that particular function. I'm a bit disappointed at the lack of functionality VW have designed into the active instrument display. The data you can show at any one time is quite limited. Some people have suggested that this was deliberate, to differentiate between VW's and the more upmarket (and more expensive) Audi's.

greg: If your car has Start Stop (as it almost certainly will have if it was sold in Australia) then it will have a Battery monitor control module integrated into the negative battery lead - which means that the vehicle is capable of measuring SOC.

This notwithstanding, I suspect that the SOC function has deliberately not been included into the your car (as you say). However, my hunch is that this is for a very different reason than you suggest - I have an Audi A3 8V which shares the same MQB build platform as your mk7 Golf and it doesn't have SOC.

My hunch (guess really) was that WV/Audi deleted SOC from their later model cars because of inquires/complaints from drivers of early model MQB vehicles. Vehicles that contain the battery monitor control module (which enables SOC measurement) also have braking regeneration.

For regeneration to work, a quantity of the battery's capacity must be "reserved" away from normal use to allow for the extra stored energy. Cars with braking regeneration AND SOC invariably registered SOC readings around 70-80%(depending on the quantity of regen energy actually created).

My suspicion is that this resulted in lots of complaints from drivers of early model mk7's - better for VAG to avoid constant explanations by removing the SOC facility in newer models - IMO, or course!

Don

[gregozedobe]

greg: If your car has Start Stop (as it almost certainly will have if it was sold in Australia) then it will have a Battery monitor control module integrated into the negative battery lead - which means that the vehicle is capable of measuring SOC.

This notwithstanding, I suspect that the SOC function has deliberately not been included into the your car (as you say). However, my hunch is that this is for a very different reason than you suggest - I have an Audi A3 8V which shares the same MQB build platform as your mk7 Golf and it doesn't have SOC.

My hunch (guess really) was that WV/Audi deleted SOC from their later model cars because of inquires/complaints from drivers of early model MQB vehicles. Vehicles that contain the battery monitor control module (which enables SOC measurement) also have braking regeneration.

For regeneration to work, a quantity of the battery's capacity must be "reserved" away from normal use to allow for the extra stored energy. Cars with braking regeneration AND SOC invariably registered SOC readings around 70-80%(depending on the quantity of regen energy actually created).

My suspicion is that this resulted in lots of complaints from drivers of early model mk7's - better for VAG to avoid constant explanations by removing the SOC facility in newer models - IMO, or course!

Don

Don: Another useful & informative post, thank you

Yes, my R did come with the annoying auto stop/start "feature" (but I disabled it with a kufatec module years ago).

Your theory about the reason for removing the SOC display is quite plausible.

I would suggest another possible reason. Besides improving the theoretical fuel consumption figures and reducing emissions, the BMS has an extra side-effect. By deliberately maintaining batteries at less than 100% SOC it has caused batteries to not last as long as they used to. I read many reports of batteries only lasting 3 years in Golfs with auto stop/start, compared with earlier Golfs getting 5-7 years life out of their batteries.

As long as not too high a % fail inside the warranty period this will increase profits for VW and their dealers, as many owners will have their batteries replaced by their VW dealers. I will of course shop around for the replacement for mine, and intend to buy an AGM to replace the inferior EFB that the car came with.

Like many recent Golfs that aren't driven every day I had noticed that my battery isn't being kept fully charged, so I now put it on a good quality charger every week to try to prolong its useful life (it is coming up to 3 years old soon). NB When charging a battery on a car with auto stop/start, always connect the -ve cable from the charger to the special BMS terminal on the firewall, not direct to the battery.

[DV52]

^^^greg: You could be correct, but I don't think that this explains why SOC has been removed in later model cars. Fact remains that regardless of the type of battery used in SS cars (EFB, or AGM), the battery capacity "headroom" is needed for regeneration. It's simply a law of physics and an immutable fact!

I'm not sure what happens with the Kufatec device, but the "usual" coding change to defeat SS doesn't remove the reserved battery capacity - the tweak simply tricks the decision maker in the car to not switch-off the engine. I also very much doubt that regeneration ceases if the driver presses the native SS-OFF button on the center console. So I suspect that these vehicles will always operate with a % of their battery capacity devoted to this facility.

Perhaps the longevity of AGM batteries is less impacted by running at slightly less than rated capacity (I don't know) but I can't see how displaying/not-displaying SOC is affected by this decision - but I might be missing the obvious!!

Don

[gregozedobe]

^^^greg: You could be correct, but I don't think that this explains why SOC has been removed in later model cars. Fact remains that regardless of the type of battery used in SS cars (EFB, or AGM), the battery capacity "headroom" is needed for regeneration. It's simply a law of physics and an immutable fact!

I'm not sure what happens with the Kufatec device, but the "usual" coding change to defeat SS doesn't remove the reserved battery capacity - the tweak simply tricks the decision maker in the car to not switch-off the engine. I also very much doubt that regeneration ceases if the driver presses the native SS-OFF button on the center console. So I suspect that these vehicles will always operate with a % of their battery capacity devoted to this facility.

Perhaps the longevity of AGM batteries is less impacted by running at slightly less than rated capacity (I don't know) but I can't see how displaying/not-displaying SOC is affected by this decision - but I might be missing the obvious!!

Don

Sorry Don, I wasn't quite clear enough with my proposed reason - it was a possible "bonus" reason for not maintaining batteries at full charge, rather than a reason for no longer displaying the SOC. In other words, by reducing the charge level on batteries VW stands to sell batteries more frequently (because they don't last as long), thus increasing or at least decreasing the reduction in profits for both VW as suppliers, and VW dealers as fitters.

I've gotten cynical in my old age, so I often "follow the dollar" method when trying to understand things that seem a little odd. Looking at the affect on profits will often help me understand what is going on.

IIRC AGM batteries have more capacity than a similar sized EFB battery, plus they are more tolerant of discharging and re-charge quicker, this adds up to a longer life in typical usage.

All the emissions related changes we are seeing revolve around profits for manufacturers, firstly by avoiding potentially very large fines in Europe if they don't meet the strict new emission targets, secondly they allow car makers to claim to be "green", thus selling more cars. A good example of this is VW don't fit the new GPFs to cars for Australia (with the excuse that there is too much sulphur in our petrol). If they were really serious about being green they would re-engineer GPFs for our petrol, but it saves them money to not fit expensive GPFs and our less strict local emissions standards allow them to do that. I haven't seen any publicity from VW about this omission. Yes, my cynicism is showing