Battery Replacement Experiment
10-09-2023, 03:32 PM
#1
Battery Replacement Experiment
I replaced the battery on my '18 SE today (Actually my favorite Indie shop did it - these old hands are not up to it these days.) The "experiment" part? They can read codes, clear codes and reset service reminders but their OBD gear won't code batteries. I've read dozens of posts on the Macan Forum on this topic most of which relate to the ability of various scanners to perform the task and few dire warnings about the consequences of failing to do so.
Porsche is not alone in "requiring" this step (BMW does it as well) I have thought long and hard on the subject - Full disclosure: I have a strong technical background in electricity and electronic and am skeptical of the process because looking at the steps we find this information input is required:
1. battery serial number
2. battery part number
3.battery type
4.battery specs
1&2 are useless and contain no useful information (in point of fact, many of the "how to" discussion note that these numbers often differ in length between brands and can be adjusted to suit)
3&4 - AGM, 92AH, 850 CCA This is the "hard" information in the system's computer and, if the new battery has the same specs, (mine does) nothing needs changing. All the computer knows at this point is that the battery has been disconnected. All the system can gather beyond this is voltage at some point (presumably at the battery terminals) and current flowing through the system - the same variables that are avialable to "adjust" (as we are told) the charging curve to avoid battery damage. My assumption - If the system can use the V & A readings to compensate for battery aging, it will use the same data to adjust for any differences in the new unit.
Here's what I have seen so far: On initial start-up a running voltage of 12.4 was displayed, different from the typical 14,6 - 14,7 volts but, after a brief stop following a very short drive, on restarting, the customary 14.6 - 14.7 number reappeared. Of course, the travel limits on the hatch and windows needed resetting.
If anything occurs to change my mind, I shall report it here.
Porsche is not alone in "requiring" this step (BMW does it as well) I have thought long and hard on the subject - Full disclosure: I have a strong technical background in electricity and electronic and am skeptical of the process because looking at the steps we find this information input is required:
1. battery serial number
2. battery part number
3.battery type
4.battery specs
1&2 are useless and contain no useful information (in point of fact, many of the "how to" discussion note that these numbers often differ in length between brands and can be adjusted to suit)
3&4 - AGM, 92AH, 850 CCA This is the "hard" information in the system's computer and, if the new battery has the same specs, (mine does) nothing needs changing. All the computer knows at this point is that the battery has been disconnected. All the system can gather beyond this is voltage at some point (presumably at the battery terminals) and current flowing through the system - the same variables that are avialable to "adjust" (as we are told) the charging curve to avoid battery damage. My assumption - If the system can use the V & A readings to compensate for battery aging, it will use the same data to adjust for any differences in the new unit.
Here's what I have seen so far: On initial start-up a running voltage of 12.4 was displayed, different from the typical 14,6 - 14,7 volts but, after a brief stop following a very short drive, on restarting, the customary 14.6 - 14.7 number reappeared. Of course, the travel limits on the hatch and windows needed resetting.
If anything occurs to change my mind, I shall report it here.
10-09-2023, 04:09 PM
#2
The Battery Type (AGM or Flooded) and the capacity (Ah) are needed for the capacity aging mathematical model used in the Battery Management System. The results of the Battery Management System is only to shut things down if the calculated battery capacity and/or state-of-charge falls below a certain threshold (ie, if the battery calculated state-of-charge is too low, the Auto Start-Stop feature is disabled, or the rear defogger (high current consumption) is disabled).
The change of the battery part number, and/or serial number just resets the capacity/aging model, because a new battery was installed. The system only sees that these numbers changed from the previously stored values.
If you don't "recode" for a new battery, I suspect nothing bad happens, other than the system weak-battery protection features may trigger prematurely.
VW and Audi use the same type of Battery Management/Protection systems, where a recode is suggested when a battery is replaced.
The change of the battery part number, and/or serial number just resets the capacity/aging model, because a new battery was installed. The system only sees that these numbers changed from the previously stored values.
If you don't "recode" for a new battery, I suspect nothing bad happens, other than the system weak-battery protection features may trigger prematurely.
VW and Audi use the same type of Battery Management/Protection systems, where a recode is suggested when a battery is replaced.
Last edited by VAGfan; 10-09-2023 at 04:14 PM.
10-09-2023, 06:49 PM
#3
I replaced the battery on my '18 SE today (Actually my favorite Indie shop did it - these old hands are not up to it these days.) The "experiment" part? They can read codes, clear codes and reset service reminders but their OBD gear won't code batteries. I've read dozens of posts on the Macan Forum on this topic most of which relate to the ability of various scanners to perform the task and few dire warnings about the consequences of failing to do so.
Porsche is not alone in "requiring" this step (BMW does it as well) I have thought long and hard on the subject - Full disclosure: I have a strong technical background in electricity and electronic and am skeptical of the process because looking at the steps we find this information input is required:
1. battery serial number
2. battery part number
3.battery type
4.battery specs
1&2 are useless and contain no useful information (in point of fact, many of the "how to" discussion note that these numbers often differ in length between brands and can be adjusted to suit)
3&4 - AGM, 92AH, 850 CCA This is the "hard" information in the system's computer and, if the new battery has the same specs, (mine does) nothing needs changing. All the computer knows at this point is that the battery has been disconnected. All the system can gather beyond this is voltage at some point (presumably at the battery terminals) and current flowing through the system - the same variables that are avialable to "adjust" (as we are told) the charging curve to avoid battery damage. My assumption - If the system can use the V & A readings to compensate for battery aging, it will use the same data to adjust for any differences in the new unit.
Here's what I have seen so far: On initial start-up a running voltage of 12.4 was displayed, different from the typical 14,6 - 14,7 volts but, after a brief stop following a very short drive, on restarting, the customary 14.6 - 14.7 number reappeared. Of course, the travel limits on the hatch and windows needed resetting.
If anything occurs to change my mind, I shall report it here.
Porsche is not alone in "requiring" this step (BMW does it as well) I have thought long and hard on the subject - Full disclosure: I have a strong technical background in electricity and electronic and am skeptical of the process because looking at the steps we find this information input is required:
1. battery serial number
2. battery part number
3.battery type
4.battery specs
1&2 are useless and contain no useful information (in point of fact, many of the "how to" discussion note that these numbers often differ in length between brands and can be adjusted to suit)
3&4 - AGM, 92AH, 850 CCA This is the "hard" information in the system's computer and, if the new battery has the same specs, (mine does) nothing needs changing. All the computer knows at this point is that the battery has been disconnected. All the system can gather beyond this is voltage at some point (presumably at the battery terminals) and current flowing through the system - the same variables that are avialable to "adjust" (as we are told) the charging curve to avoid battery damage. My assumption - If the system can use the V & A readings to compensate for battery aging, it will use the same data to adjust for any differences in the new unit.
Here's what I have seen so far: On initial start-up a running voltage of 12.4 was displayed, different from the typical 14,6 - 14,7 volts but, after a brief stop following a very short drive, on restarting, the customary 14.6 - 14.7 number reappeared. Of course, the travel limits on the hatch and windows needed resetting.
If anything occurs to change my mind, I shall report it here.
You have a battery voltage readout in your Macan?
I can't find it in my 22 GTS.
10-09-2023, 08:34 PM
#4
My experience with an Autel scanner and my 991.2 911 was that there are inputs for battery replacement, but that not all (or many) aftermarket batteries are accepted by the Porsche system in the car. If the battery does not have Porsche part numbers then the new battery data cannot be added with the scanner. If you use the old battery data you can complete the registration process but it is unknown if the data is really changed by the system. I doubt if it really makes any difference in any case.
You have a battery voltage readout in your Macan?
I can't find it in my 22 GTS.
You have a battery voltage readout in your Macan?
I can't find it in my 22 GTS.
10-10-2023, 10:14 PM
#5
10-12-2023, 10:20 AM
#6
1st Report
Drove the car yesterday (first time since Monday battery replacement) "Turn on" voltage: 12.4 volts. Initial voltage reading after start: 14.7 V. About half way through a 35 minute drive, voltage reading dropped to 13.5 volts. This is the pattern that I would expect from an "intelligent" system responding to the state of charge of a new AGM battery. (charge rate slowing as the battery approaches fully charged)