Decreasing rated range.

[glhs272]

What you wrote will definately work, although if one complains loud enough, the SC will reset the battery info manually, and you will get the same results without the range charges.

From a range calculation standpoint, resetting the battery info will fix the "calculation related" range loss indicated. But, if the battery were in fact significantly out of balance, then maybe not.

Wk057 stated earlier up thread that the balancing circuits don't kick in unless you charge to >93%. Guessing that the reason for that is it needs to be at a high state of charge to accurately calculate the differences in capacity/voltage at the group level. I don't know if that is true, but if it is then the only way to "fix" the battery is to range charge it. I don't see any other way around that, short of disassembling the battery and manually balancing it.

Of course if the battery had a weak module or group of cells then nothing will ever get that range back, short of replacing the module. It sure would be nice to have access to the diagnostic screens so we wouldn't be so much in the dark about what's going on inside the battery.

 

[qwk]

According to new evidence only a single range charge is required to activate the balancing circuits. Multiple range charges are superfluous.

With the latest FW, a single range charge doesn't do much.

- - - Updated - - -

From a range calculation standpoint, resetting the battery info will fix the "calculation related" range loss indicated. But, if the battery were in fact significantly out of balance, then maybe not.

Wk057 stated earlier up thread that the balancing circuits don't kick in unless you charge to >93%. Guessing that the reason for that is it needs to be at a high state of charge to accurately calculate the differences in capacity/voltage at the group level. I don't know if that is true, but if it is then the only way to "fix" the battery is to range charge it. I don't see any other way around that, short of disassembling the battery and manually balancing it.

Of course if the battery had a weak module or group of cells then nothing will ever get that range back, short of replacing the module. It sure would be nice to have access to the diagnostic screens so we wouldn't be so much in the dark about what's going on inside the battery.

I'm not sure what the latest FW does, but I'm 100% sure that balancing occured at 90% on the older FW versions(pre 6.0). You are right though, if the battery is out of balance, a reset will not help much.

 

[apacheguy]

Can you explain what you mean. 7.0 range charges behave differently somehow?

I'm not sure what the latest FW does, but I'm 100% sure that balancing occured at 90% on the older FW versions(pre 6.0). You are right though, if the battery is out of balance, a reset will not help much.

How do you know this? Pretty sure wk057 will beg to differ based on empirical data he has collected.

 

[rlang59]

How do you know this? Pretty sure wk057 will beg to differ based on empirical data he has collected.

A piece of data that would be needed is the FW version the car that the batteries were removed from was running. The 93% number is interesting given that pre slider the "daily" charge level was ~93%.

 

[David99]

I'm not sure what the latest FW does, but I'm 100% sure that balancing occured at 90% on the older FW versions(pre 6.0).

According to wk057 the charge level needs to exceed 93% to initiate balancing. But it then continues regardless of state of charge or driving or standing. The 93% seems to trigger it, but then it runs on it's own for however long it needs.

 

[qwk]

Can you explain what you mean. 7.0 range charges behave differently somehow?



How do you know this? Pretty sure wk057 will beg to differ based on empirical data he has collected.

Diagnosic screens do not lie....

 

[glhs272]

According to wk057 the charge level needs to exceed 93% to initiate balancing. But it then continues regardless of state of charge or driving or standing. The 93% seems to trigger it, but then it runs on it's own for however long it needs.

wk057, can you confirm that once balancing is initiated that it only needs that one balancing cycle in order to achieve a perfectly balanced pack, thus only one range charge needed? >93% triggers it, and it runs on it's own regardless of pack SOC at that point (driving or parked). But that still doesn't necessarily confirm that it gets everything done in one session. But that's what your seeing... regardless of the level of imbalance, it only takes one session to bring everything back into balance?

 

[qwk]

wk057, can you confirm that once balancing is initiated that it only needs that one balancing cycle in order to achieve a perfectly balanced pack, thus only one range charge needed? >93% triggers it, and it runs on it's own regardless of pack SOC at that point (driving or parked). But that still doesn't necessarily confirm that it gets everything done in one session. But that's what your seeing... regardless of the level of imbalance, it only takes one session to bring everything back into balance?

This is definitely not the case. Complete balancing can take a very long time(dozens of charge cycles), unless you set the slider to 100% and leave it there for a while.

 

[apacheguy]

Diagnosic screens do not lie....

Did you somehow have access to these diag screens yourself? I know that the BMS screen shows cell voltages in sets of 74 cells, but how did you know it was actively balancing?

This is definitely not the case. Complete balancing can take a very long time(dozens of charge cycles), unless you set the slider to 100% and leave it there for a while.

Not sure I understand this either. While balancing is hardly an instantaneous process, once the BMS recognizes which cells are imbalanced and by how much, it should only need to run the balancing program once.

 

[wk057]

wk057, can you confirm that once balancing is initiated that it only needs that one balancing cycle in order to achieve a perfectly balanced pack, thus only one range charge needed? >93% triggers it, and it runs on it's own regardless of pack SOC at that point (driving or parked). But that still doesn't necessarily confirm that it gets everything done in one session. But that's what your seeing... regardless of the level of imbalance, it only takes one session to bring everything back into balance?

This is definitely not the case. Complete balancing can take a very long time(dozens of charge cycles), unless you set the slider to 100% and leave it there for a while.

I think you might be confusing actual imbalance with the capacity estimating algorithm. The latter is more likely the culprit in most cases. It either needs to be calibrated with a charge to 100% and a discharge as low as possible, or reset by Tesla.

As for actual cell balancing, the vehicle and pack I experimented with was running some version of 6.2, but I doubt the behavior has changed. The balancing circuits would enable at the CV stage of the charge and stay on regardless of what SoC changes happened due to driving/charging/etc. One of the things I did was pick a random cell group in the fully balanced pack, at ~50% SoC or so I dumped 5Ah extra into a cell group and monitored the balance circuit, which would require 50 hours of balancing to fix this particular imbalance. Car behaved normally, balance circuit wasn't enabled even at 90% SoC, even though there was a pretty decent imbalance. During charging the balance circuit enabled immediately when the CV stage was reached. The balance circuit stayed enabled for over two days regardless of pack usage, which I thought was pretty cool.

Unfortunately the details of that particular project overall are not mine to share, I was only helping out and doing some experiments to try and reverse engineer some of the battery related items while I had the opportunity.

 

[Sacrament055]

2014 S40 44K ish miles I'm seeing 131 to 133 at full charge. Typically it stays at that number for a couple/few miles.

 

[AmpedRealtor]

According to new evidence only a single range charge is required to activate the balancing circuits. Multiple range charges are superfluous.

I did not recover any range after a single max charge, however after three consecutive max charges I recovered about 5 miles.

 

[msnow]

I did not recover any range after a single max charge, however after three consecutive max charges I recovered about 5 miles.

Did you run it down to <20 each time or just three 100% charges regardless of how much was used?

 

[apacheguy]

I did not recover any range after a single max charge, however after three consecutive max charges I recovered about 5 miles.

Seems that the range you "recovered" by range charging was just forcing the algo to readjust given what we now know.

 

[qwk]

I think you might be confusing actual imbalance with the capacity estimating algorithm. The latter is more likely the culprit in most cases. It either needs to be calibrated with a charge to 100% and a discharge as low as possible, or reset by Tesla.

As for actual cell balancing, the vehicle and pack I experimented with was running some version of 6.2, but I doubt the behavior has changed. The balancing circuits would enable at the CV stage of the charge and stay on regardless of what SoC changes happened due to driving/charging/etc. One of the things I did was pick a random cell group in the fully balanced pack, at ~50% SoC or so I dumped 5Ah extra into a cell group and monitored the balance circuit, which would require 50 hours of balancing to fix this particular imbalance. Car behaved normally, balance circuit wasn't enabled even at 90% SoC, even though there was a pretty decent imbalance. During charging the balance circuit enabled immediately when the CV stage was reached. The balance circuit stayed enabled for over two days regardless of pack usage, which I thought was pretty cool.

Unfortunately the details of that particular project overall are not mine to share, I was only helping out and doing some experiments to try and reverse engineer some of the battery related items while I had the opportunity.

No confusion here. The pre 6.0 FW balanced the packs at the daily slider, which is ~90%, when in range driving mode. Unless one has access to Tesla's diagnostic screens, it's very difficult to know whether the lower range displayed is pack imbalance or estimation drift. The Roadster also exhibits similar behavior, although it's not exactly the same. Tesla makes so many FW changes with each revision , that it's impossible to say for sure if things are the same now. Tesla also had a battery capacity measurement in the earlier firmwares that made degradation easy to see if the pack was balanced, and a bleed test done, but the latest FW has it buried somewhere where it's not easy to find.

 

[apacheguy]

Bleed test on the pack? What does this mean exactly? I assume this is/was a diag screen function?

under this previous FW, did the pack balance below 90%?

 

[AmpedRealtor]

Did you run it down to <20 each time or just three 100% charges regardless of how much was used?

I did not run it below 50% in this scenario.

 

[msnow]

I did not run it below 50% in this scenario.

Whatever works. I assume you got 5 more miles both at 100 and 90.

 

[AmpedRealtor]

Seems that the range you "recovered" by range charging was just forcing the algo to readjust given what we now know.

I did not drive the car below 50% during these three max charges. I simply charged to 100% for three days in a row and drove whatever miles I drove those days. My bet is on balancing.

- - - Updated - - -

Whatever works. I assume you got 5 more miles both at 100 and 90.

Yes, range went from 223 to 228 at 90% and from 248 to 253 at 100%.

 

[qwk]

No balancing below 90%.