Surprise Charge

[Billygoat]

I typically charge my Macan at home, standard level 2 charger. Usually a 100% charge clocks out at 299 miles. The other day, however, the full charge showed 340 miles on both the app and car!! I'm not sure it was real b/c it went down under 300 after a short drive.

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[rcomeau]

Don't use the range estimate as some sort of measure of what's in the battery. The estimate is based on a bunch of non-related factors that estimate consumption (range is determined by battery capacity and consumption per mile). The battery capacity is pretty much constant but consumption is a guess so changes in estimated range are more to do with changes in how the algorithm is guessing consumption rather than state of the battery.

 

[SergeyIndy]

The OP is asking why this is happening @rcomeau.

Based on what we know from the Taycan, BMCe (battery management system) performs a rebalancing of the cells (under certain conditions) resulting in more consistent voltage, charge level SoC, and possibly temperature across all modules. After this rebalancing, the car recalculates available range resulting in what you are seeing (340 miles) under its current ambient temperature, however, when you start driving, it is taking into account new driving parameters such as different temperature and your driving style, to give you its new more realistic estimate of 299 miles. Range estimate is based on simply put the worst cell SoC in the pack, so after rebalancing, all cells have more consistent SoC, so the overall range is higher.

Taycan has specific TSB that describes what to do to initiate the rebalancing that typically results in a 1%-2% bump in SoH and more range than before relabance, but unfortunately, the apps such as CarScanner do not support Macan EV yet to provide the reading for battery SoH, cell voltages/SoC/temp. The other benefit of these measurements is to detect any cells that might be going bad, which would be evident if one becomes an outlier in its voltage, SoC, or temp from other cells.

 

[rcomeau]

The OP is asking why this is happening @rcomeau.

Based on what we know from the Taycan, BMCe (battery management system) performs a rebalancing of the cells (under certain conditions) resulting in more consistent voltage, charge level SoC, and possibly temperature across all modules. After this rebalancing, the car recalculates available range resulting in what you are seeing (340 miles) under its current ambient temperature, however, when you start driving, it is taking into account new driving parameters such as different temperature and your driving style, to give you its new more realistic estimate of 299 miles.

Taycan has specific TSB that describes what to do to initiate the rebalancing that typically results in a 1%-2% bump in SoH, but unfortunately, the apps such as CarScanner do not support Macan EV yet to provide the reading for battery SoH, cell voltages/SoC/temp.

My point was (maybe not as clearly and I hoped) that people tend to over-associate changes in range estimation as a change in the battery when it is more likely due to one of the many transient assumptions used to predict consumption. Batteries are generally pretty stable (a couple % capacity degradation/year and rebalancing is not a +/- 10% thing) vs. temperature, wind, driving style all of which will change the estimation of consumption leading to wild changes in estimated range. Many refer to the range estimator in many EVs as a guess-o-meter. I've learned to ignore that value and focus on the battery state of charge when driving and not fret about the battery.

 

[SergeyIndy]

^ I totally agree with you.

 

[SergeyIndy]

My simple point is that I have seen this guess-o-meter "surprise" happen to me on a Taycan after performing cell rebalancing protocol where it showed a large jump of range of about 40 miles and then drop to reality after a few minutes of driving.

 

[SteveInKirkland]

I assume the charge to/past 100% once-a-month process to allow the BMS to recalculate is desirable for the Macan EV ... correct? I knew this at one point, but I forgot the guidance and will need to look it up.

 

[SergeyIndy]

I assume the charge to/past 100% once-a-month process to allow the BMS to recalculate is desirable for the Macan EV ... correct? I knew this at one point, but I forgot the guidance and will need to look it up.

I would assume the rebalancing protocol for Macan EV to be the same as the Taycan and pretty simple to execute. The process consists of going to near 0% SoC, keep the car undisturbed for at least 6.5 hours (no remote access via app, no key close to car, etc.), recharge back up to 100% using home charger with ideally slower than max level with 9.6kW is fine as it is already lower than 11kW than should be in the US, leave the car again undisturbed for at least 6.5 hours. That's it.

 

[SteveInKirkland]

I would assume the rebalancing protocol for Macan EV to be the same as the Taycan and pretty simple to execute. The process consists of going to near 0% SoC, keep the car undisturbed for at least 6.5 hours (no remote access via app, no key close to car, etc.), recharge back up to 100% using home charger with ideally slower than max level with 9.6kW is fine as it is already lower than 11kW than should be in the US, leave the car again undisturbed for at least 6.5 hours. That's it.

My only hesitation in copying the Taycan process completely is that 0% in the Taycan and the Macan EV seem different in real life. The Macan EV seems to freak out below 7% SoC while the Taycan seems like it can be run down to 0%.

 

[SergeyIndy]

My only hesitation in copying the Taycan process completely is that 0% in the Taycan and the Macan EV seem different in real life. The Macan EV seems to freak out below 7% SoC while the Taycan seems like it can be run down to 0%.

Taycan has at least a 2% buffer between display SoC and actual SoC. Macan EV seems to have no buffer so, I would say going down to 3% of display SoC should be good for the rebalancing procedure to occur.

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