How-to Recalibrate your SoH.

[Tooney]

I'm attaching four plots of cell voltages, two showing the change at 100% charge after sitting overnight, and two showing the change at about 12% charge after sitting overnight. I believe this shows the 'balancing' occurs at the low charge. The low-charge graph shows a total variation of .028V at 5:56PM and a variation of .008 at 5:42AM after sitting overnight. At 100% charge, the variation remains the same at .005V both before and after sitting overnight.

I've also attached the SOH readings before and after the 'rebalancing', which are quite a puzzle to me. Each time I've gone through this procedure, the SOH has DECREASED, rather than increased as it has with my previous battery. My range is still excellent, and I'm not showing a significant change, so I'm quite puzzled.

Thanks for sharing detailed, real before and after data. Good stuff.

Re SOH decreasing after discharge/recharge process:

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And the reality​

Between the motion​

And the act​

Falls the Shadow".​

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[gtm]

I'm attaching four plots of cell voltages, two showing the change at 100% charge after sitting overnight, and two showing the change at about 12% charge after sitting overnight. I believe this shows the 'balancing' occurs at the low charge. The low-charge graph shows a total variation of .028V at 5:56PM and a variation of .008 at 5:42AM after sitting overnight. At 100% charge, the variation remains the same at .005V both before and after sitting overnight.

I've also attached the SOH readings before and after the 'rebalancing', which are quite a puzzle to me. Each time I've gone through this procedure, the SOH has DECREASED, rather than increased as it has with my previous battery. My range is still excellent, and I'm not showing a significant change, so I'm quite puzzled.

.

Maybe I'm not looking at something correctly in your data but it appears your min/max difference at a low SoC went from 28 mv to 21 mv (3.390v/3.411v) after sitting. Not narrowing to 8 mv. My battery went from 59 mv to 48 mv after sitting at a low SoC (better, but nothing dramatic). After sitting at a high SoC the high SoC imbalance improved from 7 mv to 3 mv. But if I now look at the min/max at a low Soc the diff is only 6 mv (big improvement over the 48 mv seen after sitting at a low SoC). If you are able to look at your low SoC min/max diff now I think you will find it has narrowed considerably after sitting at a high SoC. Completing the whole process seems critical to having the BMS balance/recalibrate the cells.

Getting a lower SoH after rebalancing? Doesn't seem to make any sense but outside of some secret room in Stuttgart I'm not sure anyone really knows what the data represents.

 

[Vim Schrotnock]

Maybe I'm not looking at something correctly in your data but it appears your min/max difference at a low SoC went from 28 mv to 21 mv (3.390v/3.411v) after sitting. Not narrowing to 8 mv. My battery went from 59 mv to 48 mv after sitting at a low SoC (better, but nothing dramatic). After sitting at a high SoC the high SoC imbalance improved from 7 mv to 3 mv. But if I now look at the min/max at a low Soc the diff is only 6 mv (big improvement over the 48 mv seen after sitting at a low SoC). If you are able to look at your low SoC min/max diff now I think you will find it has narrowed considerably after sitting at a high SoC. Completing the whole process seems critical to having the BMS balance/recalibrate the cells.

Getting a lower SoH after rebalancing? Doesn't seem to make any sense but outside of some secret room in Stuttgart I'm not sure anyone really knows what the data represents.

Serves me right for rushing to a meeting and posting before I checked. The 'before' reading at low SOC ranges from 3.334 to 3.367, .028V difference. The 'after' reading ranges from 3.39 to 3.411, .021 difference as you pointed out. I was reading the average on the 'before' chart, not the maximum. Still, the difference is between .028V before and .021V after.

Your point about looking the low SOC after rebalancing at 100% is interesting. It's such a pain to get it down to a low SOC, it will probably take a while, but I'll definitely note it the next time I do it in a few months.

 

[Rik_CT4s]

I have no OBD scanner to check before/after, but I start the recalibration process today.

Current SOC 0% 0km. Good start. I will let it rest now until tomorrow morning (say 12 hours rest in total). Then I will charge is using 11kwh home charger to 100%.

Then let the car sit another day/night.

See what happens.
Any other tips/tricks?
Greetz.

 

[gtm]

I have no OBD scanner to check before/after, but I start the recalibration process today.

Current SOC 0% 0km. Good start. I will let it rest now until tomorrow morning (say 12 hours rest in total). Then I will charge is using 11kwh home charger to 100%.

Then let the car sit another day/night.

See what happens.
Any other tips/tricks?
Greetz.

Without access to the internal data you won't see much. If your cells are far enough out of balance you should see the GOM increase your range at any given SoC. If you were at 320 km @ 85% you might improve to 340km. I saw a 6% improvement (252 miles at 100% to 268). YMMV depending on how far out of balance your cells are. The increased range seems real based on a recent road trip. How long it lasts remains to be seen.

 

[Rik_CT4s]

This morning after 12hr+ at 0%/0km SOC I discovered it "regained" 2%/4km....i left it the day before with 0/0. Now I am charging it to 100% on 11kwh. This afternoon (local time) it will reach 100% and will leave it at 100% until the next morning. Currently SOC shows 60% (252km).

 

[Dee]

This morning after 12hr+ at 0%/0km SOC I discovered it "regained" 2%/4km....i left it the day before with 0/0. Now I am charging it to 100% on 11kwh. This afternoon (local time) it will reach 100% and will leave it at 100% until the next morning. Currently SOC shows 60% (252km).

What was your SoH before?

 

[Rik_CT4s]

What was your SoH before?

Last time Porsche checked a few months back Porsche Center told me 91%.

 

[Rik_CT4s]

Last time Porsche checked a few months back Porsche Center told me 91%.

421 km / 100% now. I will take the charger off and let the car sit overnight.

 

[Rik_CT4s]

421 km / 100% now. I will take the charger off and let the car sit overnight.

Other info that may be of interest:
46.000 km on ODO
22 inch wheels
MY22

 

[Wakesurfer]

421 km / 100% now. I will take the charger off and let the car sit overnight.

I went through the same process and my SOC is identical to yours.............260 miles @ 100% charge. It will be interesting to watch over the next few weeks/months.

 

[andb]

22 inch wheels
MY22

Excellent range with those wheels, what's your consumption?

 

[Rik_CT4s]

I went through the same process and my SOC is identical to yours.............260 miles @ 100% charge. It will be interesting to watch over the next few weeks/months.

Do you know your SOH?? Turbo s as well?

Excellent range with those wheels, what's your consumption?

I think my range on the GOM is so positive because of the "faulty" average consumption in the app/pcm....perhaps I should reset or not....
If I calculate the current say 421 km based on say roughly 80+kw battery (allowing for some degradation)..it comes close to that 19.8kwh/100km. Mind you, my driving style doesn't come close to that 19.8kw/100. As such the GOM reading for me is not realistic.

 

[VA_CT]

Attached are my charts before and after rebalancing. I couldn't get to 0% but was able to get to 8%. Battery SoH had minor 1% improvement from 89 to 90%. One interesting observation was back in May my batter SoH was at 88%. I don't see much range improvement after the rebalancing yet.

 

[Gru]

similar procédure: I went down to 9%, let it rest for the night, charged it to 100% the day after (AC 22kW) in 4hr, unplugged it and took it back 7hrs later.
SoH went from 88.9 to 90.3 [68500 km]
I didn't see much difference on the cell voltages before and after the 7hrs

before and after :

before and after :

for the record, voltages were more unequal at 9%:

before and after the night:

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