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YOUR RESEARCHBattery Replacement - Do you need to tell the ECU?
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fatal, i.e did the batteries recover, or not
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Reported cause
He didn't say whether the issue was fatal, i.e did the batteries recover, or not.
Battery Replacement - Do you need to tell the ECU?
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Leading evidence: 'fatal, i.e did the batteries recover, or not' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'fatal, i.e did the batteries recover, or not' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Adjust ambient temperature' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
No, the alternator outputs a constant voltage that is adjusted for ambient temperature.
Battery Replacement - Do you need to tell the ECU?
Install pccm
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Battery Replacement - Do you need to tell the ECU?
Install with ss nuts and washers
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Performed · outcome unconfirmed
I had my battery tray refinished and powder coated, then installed with SS nuts and washers.
Battery Replacement - Do you need to tell the ECU?
Replace battery and don�t remember doing anything special
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Performed · outcome unconfirmed
Replaced my battery and don�t remember doing anything special before or after.
Battery Replacement - Do you need to tell the ECU?
Reset automatically, some may not
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Suggestion
All these things take time to reset, some may reset automatically, some may not but as a professional I always try to save it if possible...( helps to keep customer complaints down also...lol)
Battery Replacement - Do you need to tell the ECU?
cable
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The important point about the cable is that the sign of a problem is the change in voltage between cold start and fully warmed up with is a drop of more than 1 volt, it's likely the cable.
Battery Replacement - Do you need to tell the ECU?
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Hi,
As the title suggests - I'm replacing the battery in the 996.2 C2. Do I need to tell the ECU? or is it just swapout ? I know had to tell the ECU about the new battery for my 2020 Golf GTI and 2017 Audi A4.
Second question - does PCCM+ have a pin code so that if I replace the battery I'll need to type in or anything? I'm not finding anything relating to a code in the documentation from the previous owner.
thanks Team 996
I think those codes are for factory radios only? I have a code written in my owners manual, but I've only used it when getting new keys. I don't recall any code when I installed my PCCM.
You don't need to tell the DME anything when swapping batteries
BUT
I would advice you to get one of these memory keepers so that you don't loose all radio memory, DME adaptions and calibrations, Tiptronic adaptions, one touch window fumctions, one touch sunroof functions, Seat memory functions, Convertible top calibrations,..HBA calibrations, Steering angle calibrations,Odometer trip and mileage memory, ect..
All these things take time to reset, some may reset automatically, some may not but as a professional I always try to save it if possible...( helps to keep customer complaints down also...lol)
They are so cheap and easy to use !!
Amazon
Amazon
Thanks Chip - always helpful. Think you can fill me in on what's under the battery tray?
I'm wondering if the bolts are welded to the chassis under the tray or what... Kinda scared to tackle it without knowning what's under there....
Live in Sydney, Australia. We don't salt the roads here
(never gets cold enough). I think a battery at some point has leaked some acid...
We've tried to loosen the bolts. Hit them with WD40 for an overnight soaking without success. Friend of mine wants to grind off the nuts at least to remove the tray. Unsure of next steps
Now that you mentioned the fuel pump I found this YT video
You Tube
gives me an idea
Do you really have to remove the tray? As ugly as it is, the job sounds like an unnecessary, pain-in-the-butt can of worms. Like you said, if the bolts are indeed welded to the chassis, you�ll have a difficult time trying to mock up a replacement. I�d leave it as-is until you really need to get to the fuel pump (per Porschetech3).
I had the same question. My Advance Auto Parts Die Hard H9 AGM with Varta markings is getting weak after almost 4 years. My daughter's brother-in-law is a VW tech. He said that it is only necessary if the battery has a module attached to the negative post of the battery. He said he has had multiple clients come in with dead batteries only a few weeks after replacing batteries with batteries that had the module. Coding the batteries allowed the batteries to charge. He didn't say whether the issue was fatal, i.e did the batteries recover, or not.
There is no module connected to either terminal on the 996 battery. Also, if your battery is dying after 4 years, please look at the voltmeter on the dash. If it reads below 14 on cold start and drops close to 12 or below when warm, then your problem is the Y cable is corroded and it is keeping your battery from charging properly. In that case, the Y cable is why the battery is weak. The Y cable is also called the starter alternator cable.
I've heard of this famous Y cable. My indie eyeballed it and said there's a little surface rust but they think it is ok to leave for a while. I drove the car today for an hour (very warm day today here in Sydney) and there was no issues with re-starting the car after letting it sit three times heat soaking.
My volts were reading as per below. This is pulled over idling after 50 minutes of start/stop traffic.
Volts ok?
Volts are low, so a Y cable is in your future when it drops much lower. Voltmeter has to show pretty much where you are simply to charge the battery. Here is what my voltmeter shows when the car is at final temp and it has a year-old battery, Y cable and alternator. You can see the difference.
No, the alternator outputs a constant voltage that is adjusted for ambient temperature.
When cold out the alternator outputs a higher voltage.
At 25C- ish the alternator outputs 13.8V
When warm out the alternator outputs a lower voltage.
I�m pretty sure many owners have reported voltage below 13.8v, some at 13, maybe some in the high 12�s.
When you say �when warm,� are you talking about the alternator, engine, or battery?
Doesn't the regulator control the voltage, not the alternator?
When warm, I mean the engine is at operating temperature and may be warm enough for the radiator fans to turn on. The purpose of this exercise is to point out that the Y cable is the more likely source of voltage drops to the 12v range. Mine dropped into that range and when all the radiator fans turned on, the voltage would drop to 12 or below. At that point the battery is not being charged. When the battery is not being charged, it fails prematurely. Owners who see voltage dropping ~12v range as the car fans turn on but is over 13 at startup are 99% experiencing a corroded Y cable. I posted my picture of the voltmeter reading to show what it looks like if the alternator, battery and Y cable are all new. With the engine warm and the radiator fans running, I'm just under 14V. My car had just completed a100-mile coffee run.
One thing worth noting. There are no other car electrical systems that I know of that have an electrical connection from the alternator to the battery that can fail by corrosion. Because of this, there are no commercial battery/alternator testing systems that can diagnose it. My very very knowledgeable Indy, who only does Porsche, pulled out his Snap-On battery/alternator testing system and said both the battery (newly installed by the dealer a year ago) and the alternator were bad. Neither were true, but I replaced both and the Y cable and now I'm running 14 V. The proof that it was only the Y cable was the voltage drop when warm and a physical examination of the Y cable, which was indeed toast. I wasted $1000 on that misdiagnosis and I'm hoping to help others avoid the same when they see the voltmeter drop like that.
thePRF is correct,,,
Modern 'smart' regulators have a temperature sensing element. When cold, voltage output is higher. When everything heat up,the 'heavy charging is is mostly finished and volts reduce.
It could be confusing for a starting to fail Y cable slightly decreasing voltage to be confused with regular alternator function....
jmo
I don't want to confuse this any more than I have, but when it's all new and it all warm and you have driven endless miles, the voltmeter reads 13.8V like mine and you are right about the alternator having some voltage control because my cold start is about 14.1V. If it drops below 12.5v when everything is warm, your battery isn't being charged and you most likely have a Y cable issue as the cause. The important point about the cable is that the sign of a problem is the change in voltage between cold start and fully warmed up with is a drop of more than 1 volt, it's likely the cable.
This below is from multiple sources searching for battery charging data on 12V lead acid batteries:
The optimal voltage to charge a 12V lead acid battery is typically around 14.4 volts during the bulk charging stage, which is considered a safe and efficient level for most battery types; however, the exact voltage may vary slightly depending on the specific battery and its application, with a "float" voltage (for maintenance charging) usually around 13.5 - 13.8 volts once fully charged.
Bulk charging voltage: 14.2 - 14.4 volts
Float charging voltage: 13.2 - 13.8 volts
Important factors to consider:
Battery type: AGM, gel, or flooded lead-acid batteries may have slightly different optimal charging voltages.
Temperature: Charging voltage should be adjusted slightly based on ambient temperature.
Agree with all of this.
I just want to say that 12.4-12.7V is about steady-state of a healthy battery that�s fully charged. Anything below that, and energy is leaving the battery. Anything above that, and energy is entering the battery.
So if folks see 12.8-13.2V being displayed, that doesn�t mean there is a problem any more than seeing 14.4V being displayed means their charging systems are in better shape than if less.
During engine startup, it�s fine if voltage drops well below 12V as the current demands are high and temporary (expected behavior).
This is a source reference. Confirm exact model applicability in the original material.
