Scan My Tesla results for S 75D from July 2018

[lukearlo]

Hi guys, I was wondering if there is anyone here who could check data for me and see if that pack is healthy.

Car in question is Tesla Model S 75D from July 2018 with 147,212 miles / 236,195km

I have purchased Scan my Tesla accessories and trying to get to the bottom of data, I mean everything looks OK to me but it is very hard knowing without comparing these figures to a similar car to mine.

Things which are worrying, maybe they are not.

Battery current SOC is at 57%

*Battery voltage is showing as 320V - should we be concerned here or not at all? I believe 75kwh packs are 350V not 400V so maybe at higher SOC it will be closer to 350V?

*Battery degradation, it is showing as nominal capacity of 62KwH, which depend what figure we actually use for brand new battery pack, it is about 13% degradation, seems a bit high considering that DC charging was only about 30% of total charging, the rest was AC charging at home.

*Cells - well the number of cells looks strange to me, it appears that there are 83 not 84 cells? Does it sound correct?

*Cells voltage, it seems to be varying from 3.847V to 3.853V does it seems correct or too low, again it might be ok at 57% SOC, am I reading i right?

Based on pics, is there anything else in the data I should be concerned about please?

 

[lukearlo]

Here are the rest of screenshots from SMT

 

[islandbayy]

Your CAC imbalance is rather high at 9.5Ah. This number isn't the most accurate on SMT, however a good guideline. At that level, you may see a BMS error sometime soon. Tesla has changed some things recently with the BMS, the rough trigger for a BMS warning was ~8.5 Ah imbalance. So you are already past that.
Do a charge up to 100%, then run it down to around 10% without charging at all in between, and post your cell voltages are, and voltage imbalance. That will give a better idea of the cell imbalance.
You should still be under Battery warranty.
I'd also recommend checking out www.SuperchargerTravel.com and join the Tesla battery group to learn more. At least you are under warranty for 2 more years-ish. Once you are out of warranty, there are more options though.

 

[lukearlo]

Your CAC imbalance is rather high at 9.5Ah. This number isn't the most accurate on SMT, however a good guideline. At that level, you may see a BMS error sometime soon. Tesla has changed some things recently with the BMS, the rough trigger for a BMS warning was ~8.5 Ah imbalance. So you are already past that.
Do a charge up to 100%, then run it down to around 10% without charging at all in between, and post your cell voltages are, and voltage imbalance. That will give a better idea of the cell imbalance.
You should still be under Battery warranty.
I'd also recommend checking out www.SuperchargerTravel.com and join the Tesla battery group to learn more. At least you are under warranty for 2 more years-ish. Once you are out of warranty, there are more options though.

Excellent, thanks for that. Seen someone had 22 and was still driving fine, no idea but good to know. I have warranty until September 2026 luckily

 

[brainhouston]

*Battery voltage is showing as 320V - should we be concerned here or not at all? I believe 75kwh packs are 350V not 400V so maybe at higher SOC it will be closer to 350V?

yes

*Battery degradation, it is showing as nominal capacity of 62KwH, which depend what figure we actually use for brand new battery pack, it is about 13% degradation, seems a bit high considering that DC charging was only about 30% of total charging, the rest was AC charging at home.

ur degradation is roughly true, batteries degrade with any charging

Tesla’s hacked Battery Management System exposes the real usable capacity of its battery packs

Like most automakers, Tesla measures the battery capacity of their electric vehicles by the total energy potential of the pack rather...

electrek.co

*Cells - well the number of cells looks strange to me, it appears that there are 83 not 84 cells? Does it sound correct?

not sure but someone posted once that tesla was doing some remans i guess at some point n was cutting out bricks so maybe u got one of those...

*Cells voltage, it seems to be varying from 3.847V to 3.853V does it seems correct or too low, again it might be ok at 57% SOC, am I reading i right?

Based on pics, is there anything else in the data I should be concerned about please?

ur V imbalance is good, no issues there
ur CAC imbalance is higher than other packs (mine is 5Ah, 90kwh, 103kmi) but it can go up to 20% at which point u get u018 error

 

[lukearlo]

yes

ur degradation is roughly true, batteries degrade with any charging

Tesla’s hacked Battery Management System exposes the real usable capacity of its battery packs

Like most automakers, Tesla measures the battery capacity of their electric vehicles by the total energy potential of the pack rather...

electrek.co

not sure but someone posted once that tesla was doing some remans i guess at some point n was cutting out bricks so maybe u got one of those...

ur V imbalance is good, no issues there
ur CAC imbalance is higher than other packs (mine is 5Ah, 90kwh, 103kmi) but it can go up to 20% at which point u get u018 error

Ah ok, so basically I need to drive it preferably a lot to make sure that failing will happen within the warranty period. Thanks for that. Is it dangerous driving it with 9.5Ah CAC imbalance? Since I’m planning couple of European trips and don’t want to be left at the middle of the road…

 

[islandbayy]

Ah ok, so basically I need to drive it preferably a lot to make sure that failing will happen within the warranty period. Thanks for that. Is it dangerous driving it with 9.5Ah CAC imbalance? Since I’m planning couple of European trips and don’t want to be left at the middle of the road…

At that CAC Imbalance, it could happen before you even leave your home. It's a toss up. Like I said, some things have changed in more recent firmware updates. Last year that likely would have already been triggered. This year, seems more like Tesla is letting them get worse to try and get them further past warranty before failure. I'd personally just drive it. You'd benefit far more by having it fail, on road trip or not, than having it fail outside warranty...

 

[islandbayy]

Again, I'd recommend joining the Tesla battery group from www.SuperchargerTravel.com as we nearly all the worldwide third party battery pro's. They'd likely be able to give more detailed response than I could, and more up-to-date opinions on when it may fail.

 

[lukearlo]

Again, I'd recommend joining the Tesla battery group from www.SuperchargerTravel.com as we nearly all the worldwide third party battery pro's. They'd likely be able to give more detailed response than I could, and more up-to-date opinions on when it may fail.

Absolutely, thank you for that

 

[brainhouston]

fyi, based on my car n back of napkin math..

307 v (83 bricks at 3.7v) x 217Ah (max brick cac) - 4kwh (buffer) = 62kwh
not sure why tesla uses max brick, since ur technically not gonna get that in reality, min brick cac will set the limit
same formula checks out for my numbers

 

[lukearlo]

fyi, based on my car n back of napkin math..

307 v (83 bricks at 3.7v) x 217Ah (max brick cac) - 4kwh (buffer) = 62kwh
not sure why tesla uses max brick, since ur technically not gonna get that in reality, min brick cac will set the limit
same formula checks out for my numbers

So I did this calculation slightly differently, used 83 bricks x average v @3.853 x average brick CAC @ 212 /1000 - 4kW buffer and got 63.797kW hmmm

 

[lukearlo]

Quick update, after having some chat on facebook group suggested by another user here, I was told that Ah imbalance value must be at certain percentage to throw an error and that is usually 20%, mine seems to be around 5%, that if we trust SMT reading for CAC as developer of the app himself said he only gathered some data but cannot trust it 100%. So maybe I should check it with other tools.