Hi all
On october '17 I had unplugged my negative terminal on the battery (Varta H3 100Ah) to see if some persistent fault codes would go away. It remained so for 3-4 days, and I wasn't planning to leave it unplugged for so long but I fell ill right after unplugging and couldn't even get up. After I plugged it back, my car began to act funny. But things have taken a worrying turn recently.
Basically, here's my (main) problem, when I start the car, using the hidden menu :
-voltage goes from 11.8 to 12.2 at my first journey
-then after 15 mins of constant driving, it goes to 13.8-14.4v
-then, i'd say after 7-8 mins of driving, it starts going from 14.8 to 15.2
-and then after ~10 mins, things get worse as I see the voltage dropping randomly to 13.8, 13.5, then going up to 14, 15, then going down, then up, then down
-it eventually stabilizes to 14.5-15...
During each of these "steps", I can clearly see the voltage going up and down quickly, even worse, I can feel it because the rpm jauge fluctuates as well and it's painful to observe. Turning on the AC seems to cause the fluctuation to happen even sooner. I insist it does that EVERY day, to the point I even know at which portion of the road the voltage will be at 14.4...
The most confusing part of this issue is why it seems to escalate and how "scheduled" it is. And it's always the same pattern. 11v then 13-14v then 15v, then hellish fluctuations, then stabilization.
I've read a failed alternator would simply not charge the battery, but my last battery held its charge for 5 months, before dying on march 30th. And it only died because I was often using ISTA-D without firing up the engine (that software always takes 2-3 mins to scan all modules, so I paid the price..), otherwise, i'm 100% sure it would still be on.
So I bought another battery (95Ah), registered it with ISTA. Worked fine for a few weeks, until 2 weeks ago after leaving my car parked for 2 days only, it started displaying all kind of error messages on Idrive. When it does that, I know it's because the battery reached a critically low state of charge. But I still managed to drive a few km until the limp-mode made it too slow to continue driving. After I parked it, I tried to restart but it wouldn't. Just not enough power, resetted date and time as well as the Xmas tree symptom. We jump-started, got home, and the next day I started it without any issue, and I drove for 80 kms (with the same escalating symptoms mentionned above though), did my business, and on the way home, with AC/radio/auto windshield wipers on, it suddenly displayed again the Xmas tree, and within a minute the car had gone to as low as 10.9v. I know people say it's automatically a definitive dead battery but I have no choice atm but to charge it and keep using it.
So I was thinking, if it's not my alty, it'd be my voltage regulator, but apparently it causes the voltage to go higher than 16v, a voltage my car never reached (highest it reached was 15.8 or 15.9, but never a clear 16v, and it was during a time where I had absolutely no apparent charging issue at all). Then I thought, it's the IBS, but still no noticeable difference when both cables are unplugged. I also cleaned my terminals, still no good news.
I'm not sure it's all clear to you people but I wanted to give as many informations as possible (I even omitted to report some other misadventures to make it shorter). I just don't want to start throwing money at random parts, especially given the price of an alternator (even the reg' isn't that cheap). I don't understand the escalating symptoms. It doesn't match any of the regular issues i've read online, the car never suddenly died while driving, it would show symptoms BEFORE dying. It seems to be a combination of both failed alty/VR, and at the same time, none of them...
On october '17 I had unplugged my negative terminal on the battery (Varta H3 100Ah) to see if some persistent fault codes would go away. It remained so for 3-4 days, and I wasn't planning to leave it unplugged for so long but I fell ill right after unplugging and couldn't even get up. After I plugged it back, my car began to act funny. But things have taken a worrying turn recently.
Basically, here's my (main) problem, when I start the car, using the hidden menu :
-voltage goes from 11.8 to 12.2 at my first journey
-then after 15 mins of constant driving, it goes to 13.8-14.4v
-then, i'd say after 7-8 mins of driving, it starts going from 14.8 to 15.2
-and then after ~10 mins, things get worse as I see the voltage dropping randomly to 13.8, 13.5, then going up to 14, 15, then going down, then up, then down
-it eventually stabilizes to 14.5-15...
During each of these "steps", I can clearly see the voltage going up and down quickly, even worse, I can feel it because the rpm jauge fluctuates as well and it's painful to observe. Turning on the AC seems to cause the fluctuation to happen even sooner. I insist it does that EVERY day, to the point I even know at which portion of the road the voltage will be at 14.4...
The most confusing part of this issue is why it seems to escalate and how "scheduled" it is. And it's always the same pattern. 11v then 13-14v then 15v, then hellish fluctuations, then stabilization.
I've read a failed alternator would simply not charge the battery, but my last battery held its charge for 5 months, before dying on march 30th. And it only died because I was often using ISTA-D without firing up the engine (that software always takes 2-3 mins to scan all modules, so I paid the price..), otherwise, i'm 100% sure it would still be on.
So I bought another battery (95Ah), registered it with ISTA. Worked fine for a few weeks, until 2 weeks ago after leaving my car parked for 2 days only, it started displaying all kind of error messages on Idrive. When it does that, I know it's because the battery reached a critically low state of charge. But I still managed to drive a few km until the limp-mode made it too slow to continue driving. After I parked it, I tried to restart but it wouldn't. Just not enough power, resetted date and time as well as the Xmas tree symptom. We jump-started, got home, and the next day I started it without any issue, and I drove for 80 kms (with the same escalating symptoms mentionned above though), did my business, and on the way home, with AC/radio/auto windshield wipers on, it suddenly displayed again the Xmas tree, and within a minute the car had gone to as low as 10.9v. I know people say it's automatically a definitive dead battery but I have no choice atm but to charge it and keep using it.
So I was thinking, if it's not my alty, it'd be my voltage regulator, but apparently it causes the voltage to go higher than 16v, a voltage my car never reached (highest it reached was 15.8 or 15.9, but never a clear 16v, and it was during a time where I had absolutely no apparent charging issue at all). Then I thought, it's the IBS, but still no noticeable difference when both cables are unplugged. I also cleaned my terminals, still no good news.
I'm not sure it's all clear to you people but I wanted to give as many informations as possible (I even omitted to report some other misadventures to make it shorter). I just don't want to start throwing money at random parts, especially given the price of an alternator (even the reg' isn't that cheap). I don't understand the escalating symptoms. It doesn't match any of the regular issues i've read online, the car never suddenly died while driving, it would show symptoms BEFORE dying. It seems to be a combination of both failed alty/VR, and at the same time, none of them...
