Battery dying?

[Jondalar]

J
Yes, the control modules can see that the voltage has been re-established (after disappearing for a few minutes), but how does the car distinguish between other events that cause this symptom (i.e. battery voltage collapse from a weak battery and battery lead remove and re-connection) and the less frequent act of an actual battery replacement? AGM batteries are also fairly smart devices, but they don't talk to control modules in a way that discloses their identity - they are just batteries!

I'd like to give the road-assist person the benefit of the doubt and suggest that he/she was probably referring to the error reports that were generated in the removal/replacement exercise and that have subsequently cleared. But it's folly to believe that the car has a similar IQ to that of the road-assist guy and could therefore know that the battery was replaced - without any changes to the CAN Gateway module settings (IMO). If this were the case then there would be no need for Ross-Tech to create their video on battery replacement and there would no need for VW to make the three adaptation channel settings available for consumer use (IMO)

Don

Thanks for the reply, I do have an OBD Eleven module so I'll have a play with that next time I get a chance. It's a bit sad than an actual VW roadside assist person wouldn't know about the battery system properly though.

Cheers,
Karl

[BlitzAce]

Not sure I remember where I read these - but I recall some one saying if the new battery isn't adapted to the car, simply speaking the car would think it's the same old one, and overcharges it over time to compensate for the.. not sure how to put it - because all batteries gradually lose their charge capacity over the years? And it will simply kill the new battery in time, as well.

Although I've also read oh how the battery module is adapted from Audi, and in Audis they simply learn the new settings over time, with no ill-effects..?

However in my own experience, I know at least 3 people that had their batteries changed by our local dealer - and the replacements died in less time than the original ones. Out of curiosity I plugged in their cars to my VCDS and found out all of them have the default settings which came with the car (the battery serial number is the same, IINM it was 00000 or something), thus strengthening my first point above. Although, I asked our dealer and they too, said, no settings are necessary - the car will self learn (with the cynical 'what does he know' look from the staff.. albeit I bet I've owned far more VWs than the dude).

Comments, anyone?

[DV52]

Not sure I remember where I read these - but I recall some one saying if the new battery isn't adapted to the car, simply speaking the car would think it's the same old one, and overcharges it over time to compensate for the.. not sure how to put it - because all batteries gradually lose their charge capacity over the years? And it will simply kill the new battery in time, as well.

Although I've also read oh how the battery module is adapted from Audi, and in Audis they simply learn the new settings over time, with no ill-effects..?

However in my own experience, I know at least 3 people that had their batteries changed by our local dealer - and the replacements died in less time than the original ones. Out of curiosity I plugged in their cars to my VCDS and found out all of them have the default settings which came with the car (the battery serial number is the same, IINM it was 00000 or something), thus strengthening my first point above. Although, I asked our dealer and they too, said, no settings are necessary - the car will self learn (with the cynical 'what does he know' look from the staff.. albeit I bet I've owned far more VWs than the dude).

Comments, anyone?

Blitz Ace: Hello. My position is that the good Burghers at VW have themselves to blame! If their general approach to all their cars' technology wasn't so shrouded in secrecy, them perhaps all of us (me included) might be writing actual facts, rather than speculation!

I'm guessing, but I'm not sure that your observations regarding the longevity of the replacement batteries for the "3 people" necessarily resulted because of a failure to alter the 3 x adaptation channel settings in the CAN gateway. In my experience, there are some absolutely crap batteries out there which dealers/retailers will happily sell as exact replacements but which are no-where as good as the batteries in new vehicles - because car manufacturers have much better purchasing power and because they are able to scrutinize their stock much more professionally!

Perhaps the mk7 is intelligent enough to modulate the charging characteristics of a battery taking into account its age and its capacity depletion curve over time- I'm not sure (but I wouldn't have thought so - I would have thought that such matters would have been more determined by the fundamental laws of physics such as the degradation in the internal impedance of the battery, itself) My own personal conclusion after reading VW's material is that the opposite is true. That is, the greater the period from battery replacement, the less it matters that the CAN Gateway was not informed of the change - because the historic battery table is gradually overwritten with the performance of the new battery. But I'm more than happy to be proven wrong!!

Don

[BlitzAce]

Well.. yea? Nothing conclusive at this point I guess. Although I've taken it to replace the stock EFB with a slightly higher capacity Varta Silver E39 AGM, even though I'm still under warranty for the battery. Even bought a C-Tek Start/Stop charger for periodical maintenance (at least that's the idea..). And I recall another point - the 3 owners who already had their batteries replaced by the local dealer didn't notice any low battery warning before their battery died again, visually or audio like previously, while on the stock battery the car came with. I would say it's because the battery module can't really tell the battery is low since it wasn't coded properly during the change..? I don't know.

I'm still appalled that most of the people I know had their cars dying on them, the batteries I mean, in less than 2 years. Pretty much almost all of my mk7 friends had their batteries changed, by now. I'm on my 2nd replacement battery myself, and I got the car in July or so, 2014. I would say it's the hot weather and all the Start/Stop, ambient lights and everything the mk7 has, but honestly, a proper explanation would be good. Been lurking around for quite a while, and if a resident expert such as you has doubts than I guess the search for answers is still ongoing, I suppose. Not on the quest on proving who's right or wrong here, just needing answers for the good of us 7 owners

[mattchuu]

Is there any wisdom on using a ctek mxs 5 charger on a golf 7 gti?

I use it every couple of months on an older mk5, but i always disconnect the battery and charge it.

I'm punishing my battery with SS and a dashcam, so i'd like to periodically top it up for 24h to get it back to full charge.

If i recondition the battery, should i disconnect it from the car? it does put 16v through, so i doubt that would be good for the car?

Matt

[Transporter]

Is there any wisdom on using a ctek mxs 5 charger on a golf 7 gti?

I use it every couple of months on an older mk5, but i always disconnect the battery and charge it.

I'm punishing my battery with SS and a dashcam, so i'd like to periodically top it up for 24h to get it back to full charge.

If i recondition the battery, should i disconnect it from the car? it does put 16v through, so i doubt that would be good for the car?

Matt

Don't disconnect the battery in your car with ss technology. Always connect properly, the negative to chassis battery earth and positive to the battery. Standard charging only.

[DV52]

^^^^ what he/she? said!!

......... and if you do disconnect and "recondition" the battery because the paranoia of an over-used battery is too great (which it shouldn't be, because EFB/AGM batteries are designed for the punishing operation of Start stop), flip the serial number in the CAN Gateway - I forget how many digits in the number, but it's quite large, so I doubt that you will run-out of numbers (and if you do, I'm fairly certain that the control module allows the use of a previously used number)

Don

[mattchuu]

So i should connect the charger to the Chassis ground point, not the battery negative terminal? that makes sense since there's a current shunt on the negative terminal monitoring the battery.

I've been doing a lot of <5 min trips and i have a dashcam that runs in parking mode, i've been noticing that the voltage is now almost always about 12.0v, so the battery is getting nailed and never charged, so i'll top it up and try to do some longer trips!

on the pus side, SS hasn't stopped the engine in a couple of weeks now!

[BlitzAce]

My Golf's SOC is showing around 60-70% normally. I know I probably shouldn't be worried but.. somehow I am.

[DV52]

S

I'm actually tempted by this little gadget too:
Ctek CTX Battery Sense Bluetooth Battery Monitor Iphone Android Data Logging | eBay

The_Hawk: Wow - $68!! Why not buy yourself a cheap bluetooth ELM dongle and plug it into the OBD port (OBDII gives you all the information that the CTX unit claims to show)! Better still, just implement the SOC (State-Of-Charge) tweak - it costs nothing if you already have a VCDS/OBD11 device!

Don
PS: I'm always dubious about 2 x wire devices that promise to tell everything about a battery (from it's voltage alone - I assume). How is this possible without knowing the exact nature of the battery's construction, its history and the temperature of the battery? At least the OBD prediction of the car's SOC has the benefit of the current-shunt on the negative battery clamp and a history file, and the mk7 makes an estimate of battery temperature from the Battery type entry in the CAN Gateway and the car's measurement of ambient temperature. Not 100% accurate I agree - but a whole lot better than a simple 2 x wire device IMO!!