Long winded post, Please bear with me:

Left dash cam on whilst I was away for a few days and came home to a flat battery.

It was at night and dark and and didn't notice the sticker that says not to connect to the negative terminal on the battery.

Connected jump pack to negative terminal with no joy and then jump leads from another car the same way with no joy.

Ended up charging the battery off the car, the car then started ok but with several warning lights that went out once I went for a drive.

I have been using the car for the last 3 weeks and everything appears to work ok apart from the Battery SOC display which now shows: SOC ---% and the car displays that I need to go for a drive after being parked for a few days where as I have not had this warning before. If I go for the run then this is not displayed anymore.

The stop start had already beed disabled by changing the stop start voltage from 7.6v to 12v (vcds)  last year as I do not want stop start anyway.

I have now learned that the reason not to connect to the negative terminal is that there is a battery control module attached and if you connect to this then it will throw out the current battery stats

I understand that these stats are for the stop start (if the battery doesn't have enough charge the stop start will not work) Please correct me if I am wrong.

 

My questions are: What damage is done by not jump starting the correct way i.e connecting to negative battery terminal?

                                 Will the battery control module need to be replaced or can it be reset and if so how?

                                 Any other thoughts (yes I know I am an idiot)

 

Surely im not the only fool to make this jump start error

Thanks in advance

 

A bit late but yes you are correct but you also have a smart charge system which uses the same sensor to assess the soc, with smart charging the EMU will stop the alternator charging the battery via the engine if the SOC is above 75/80%, that`s to leave room in the battery for any regeneration from braking or overrun which occurs at a higher rate of charge around 16 volts which if pushed into a fully charged battery would overcharge and ruin it. As you have already disabled stop/start just disconnect the sensor on the negative battery lead that will force the alternator into standard default charging mode 13.8 to 14.3 volts which will give you a fully charged battery unlike smart charge whereby the battery can be as low as 75% charged a great deal of the time. This is the same standard mode my Audi TT MK1 charges at.

 

I run both my Merc`s with this sensor disconnected mainly because stop/start can`t be coded out on Merc`s , SLK just past its MOT with sensor disconnected, try it you can always plug it back in.

Edited 4 April, 20197 yr by Bobclive2

18 hours ago, Bobclive2 said:

regeneration from braking or overrun which occurs at a higher rate of charge around 16 volts

How does that work please? I thought that the regulator stopped the alternator putting out more than 14.4v.

9 hours ago, KenONeill said:

How does that work please? I thought that the regulator stopped the alternator putting out more than 14.4v.

 

9 hours ago, KenONeill said:

How does that work please? I thought that the regulator stopped the alternator putting out more than 14.4v.

 

This is a smart system with regeneration, the alternator is controlled by the Engine management unit (EMU) , with a fixed charge alternator prior to Stop/start and energy regeneration the EMU was not involved, in this case the regulator kept the voltage within the range of around 13.8 to 14.5 volts, I have this type on my Audi TT MK1. As Said, for regeneration to work effectively the alternator needs to get energy into the battery quickly otherwise there would be even less benefit than that available from this system at present, which I believe is minimal.  As said earlier, there needs to be room in the battery (normally 20/25%) for this high charge rate of up to 17 volts (in some makes of car) otherwise the battery would be overcharged and fail.             

Regeneration is normally in short bursts and this High voltage is needed to try to make the system worthwhile, I have found there are minimal gains to the driver but there is one big disadvantage, the system often leaves the battery only partially charged hence all the complaints mentioned in my earlier post.

@Bobclive2 OK thanks. I've always been dubious the actual fuel saving from these systems on a basically IC vehicle, since realising that a Citroen BX did the same ECE15 numbers as a Peugeot 405 with the same engine despite the BX having a hydraulic pump to drive suspension and brakes as well as PAS (when fitted).

kenOneil,

 

 

 

This may only relate to Hyundai i40, so not sure how much charge goes into the battery of other makes or models smart systems, just makes you wonder what`s next as more pressure is put on manufacturers to make these (save the planet from CO2 emission targets), sob the customer. All I want is a reliable car that starts when I want it to and doesn`t have stop/start, thats why I disconnected the sensor, I had no idea this smart system existed until I decided to try and find a way of deactivating stop/start on my Merc.

 

Attached is A PDF from Hyundai UK explaining about the AMS system. The text from this pasted below.

This model has an engine ECU controlled alternator and this is designed only to operate in a way that reduces fuel consumption and emissions. So effectively it will actually do very little unless it really needs to, which means that until it detects an electrical load from things such as headlamps, HRW etc it will do the bare minimum to charge the battery up. If the customer is only doing those sorts of short journeys and not using any electrical items then the starting of the engine has taken charge out of the battery, but without any electrical items being used it won’t put that much back into the battery again. The Alternator Management System (smart charge) works in a very different way to a conventional alternator. The conventional alternator is charging at all times whenever the engine is running, and will increase its output back to the battery depending upon electrical load and the speed it is being rotated at. In the AMS system the charging function of the alternator is controlled electronically by the engine control ECU based upon various sensor inputs and how the vehicle is being driven, so it can be that the alternator will not be charging the battery at all dependent upon the circumstances at that time. Effectively as the alternator is controlled via the ECU it will only charge the battery when necessary, this is to reduce emissions and improve fuel economy. In certain conditions the system will only charge the battery in small amounts.

 

According to Hyundai and other independent testing, this Intelligent Stop & Go system can save drivers as much as 15 percent on fuel. Plus, with less idling, you'll reduce your overall carbon emissions for a healthier drive, repeat for the true believers, reduce your overall carbon emissions for a healthier drive,

 

Carbon emissions at present in the atmosphere  are 408 ppm, plants love it they give 40% more yield at 1200 ppm, it`s at that level in commercial greenhouses, up to 10,000 ppm in submarines and up to 5000 ppm in the space station, no one has ever been caused harm what so ever by breating in CO2 at below 8000 ppm, ever, it`s all bullsh*t.

 

https://www.nap.edu/read/11170/chapter/5

 

http://www.talkhyundai.com/hyundaiforumuk/topic/26751-start-stop-isg-and-agm-brattery/
 

Edited 8 April, 20197 yr by Bobclive2

Hyundai appear to be trying to deliberately mislead there.  They want to imply that the conventional alternator outputs a fixed amount of power, much of which is wasted much of the time (they don't say where it goes though).

 

In fact conventional alternators control their output neatly by PWM'ing the field current to provide the bare minimum current generation to keep their output voltage at the setpoint. In this way they are demand led, to do whatever it is they need to do to keep the battery optimally charged, and no more.

 

 

OK, thanks Bob. I believe that you've quoted Hyundai, but do not believe this 15% claim.

Edited 8 April, 20197 yr by KenONeill

kenoneill, 

 

Regarding disconnecting sensor and reverting to standard constant charging, it appears according to this blog, ( http://www.fordaustraliaforums.com/forum/showthread.php?54391-Smart-Charge )  read all the posts, most interesting that Ford will deactivate smart charging on this model with no charge and within warranty. As smart charging systems are similar in all makes of ICE cars and judging by my Merc being disconnected for the last 6 months reverting to a standard continuous charge will not cause issues, 

 

From mentioned blog,

Post 68,
@ sugar...
I have had mine disabled and it has NOT affected economy in any way. In fact my economy has improved, where I were averaging
about 200 kms per 1/4 tank I am now at about 220 kms per 1/4 tank.
I honestly can not understand how it would decrease economy.