No i don’t. Car had behaved this way since day 1.Do you have that option where the brakes are applied to mimic regen ?
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No i don’t. Car had behaved this way since day 1.Do you have that option where the brakes are applied to mimic regen ?
Of course the BMS is involved but the reason for the other chemistries (NCA/NMC) not taking regen at high SOC is that the battery cells never can be (must not be) exposed for a voltage higher than the maxiumum cell voltage, thats 4.20V/cell. If the battery is full it it charged to 4.20V/cell so even the slightest regen during the first km would increase the cell voltage to above 4.20V. Its a hard limit, and the BMS has to follow that.Regen is not battery capacity dependent, it is BMS dependent. Agree that 100% is not true 100% but the car can also be set to allow no regen above 90%. See case of Powerwall that will no charge battery until down to 60%. It is all software.
It was a general statement, and also included hes own home-battery.You can hear his statements starting at 37:50.
Not necessarily.There must be some sort of top buffer for the LFP as there is still a lot of regen when the battery is fully charged.
The actual amount I do not know, but clearly if it was 100% true SOC there would be zero regen.
Charging to 100% = resetting the energy counter in the BMS to 100% energy, a known value instead of calculated.So the best practice is still charging to 100% at least once a week but don't stay at 100%, get back to 70% or lower as soon as possible after hitting 100%?
Charging to 100% = resetting the energy counter in the BMS to 100% energy, a known value instead of calculated.
Staying at or below 70% will reduce the calendar aging - 100% is no crisis, opposite to most forum rumors.
Remember that the batteri will hold up anyway, by following the manual.
Did you see the picture in this post? LFP Calendar agingstaying at 100% for days is no crisis too? Seem like the calendar aging speed up pretty quickly with 100% and 25 degrees to 35 degrees which is a more practical temperature range instead of 15 degrees.
The charging to 100% myth for LFP is completely overblown.staying at 100% for days is no crisis too? Seem like the calendar aging speed up pretty quickly with 100% and 25 degrees to 35 degrees which is a more practical temperature range instead of 15 degrees.
The charging to 100% myth for LFP is completely overblown.
Charge to 100% as often you need to, just do not leave it there for extremely long periods of time (weeks, months). Days is ok. Weeks or months not so much. But even so, as AAKEE demonstrated, that means an extra 3% degradation. Does it matter? If you didn't check the range display you would never even know.
Yes the optimal practice is to charge to 100% once a week and then drive the car to below 70% the remainder of the time. If you want to go even further, drive it below 40%! Where does the madness end?
It is very unlikely that you will charge your car to 100% and leave it like that all the time. Unless you have a wall charger in your garage and you can micro manage the battery for fun, I wouldn't worry too much about it!
The LFP is best for newcomers to EV's as it can be treated like a ICE vehicle - charge to full once a week and run it to a low % before charging again. Since LFP mostly degrades from calendar ageing, this is a better way to look after the battery (unlike NCA).
LFP's are very sensitive to a higher voltage. You must not charge above 3.65V or risk damaging the cells. Normally you charge at 3.65V until the charging current drops to a nominal cutoff value (not good to float charge at 3.65V) - the cells are then nominally at 100%. You can still charge again (e.g. regen), but only at 3.65V, and the charging current will be low (so not much regen available).It could be that the LFP's are not sensistive to higher voltage than the 100% end charging voltage, and also that they have a low internal resistance at 100% allowing to regen with good power without the need to increase the voltage high.
I agree that the figures in that post don't add up, so there is error either in the 381V or the individual cell voltages - I would dismiss the 381V and just look at the individual cell voltages because it is vitally important for a BMS to have accurate individual cell voltages.According to this post, with Scan my Tesla data from a fully charged LFP, the total votlage was 381V after the charge. 106 cells in series means 3.594V/cell in average. (the post also states CVMax 3.544 which doesnt seem to match really).
That is the cell voltages after charging and parking (according to the post) but it won't be the resting voltage - the resting voltage of LFP at 100% would normally be close to 3.4V (or even high 3.3xV), so I don't think these cells have rested for very long. (There is no accurate resting voltage for 100% charged LFP cell - that is why we need to charge to find 100%, but it should be near 3.4V).We can see that if we have a resting voltage after the charge of 3.55-3.59V/cell, we are at or very very close to 100%.
I have just come to the conclusion that LFP batteries have 108 cell bricks not 106.I agree that the figures in that post don't add up, so there is error either in the 381V or the individual cell voltages - I would dismiss the 381V and just look at the individual cell voltages because it is vitally important for a BMS to have accurate individual cell voltages.
Then we most probably have the solution to wy regen works at 100%:That is the cell voltages after charging and parking (according to the post) but it won't be the resting voltage - the resting voltage of LFP at 100% would normally be close to 3.4V (or even high 3.3xV), so I don't think these cells have rested for very long. (There is no accurate resting voltage for 100% charged LFP cell - that is why we need to charge to find 100%, but it should be near 3.4V).
I guess you agree that according that post and voltages there is no upper buffer and the cells are actually charged to 100%?The above is from my knowledge of LFP, but not Teslas specifically.
What car, battery and make?I have just come to the conclusion that LFP batteries have 108 cell bricks not 106.
I made a post in the Australia thread which I won’t cross post here, but my Battery voltage is 343V and divided by 108 that equates to my Cell Volt Average.
Also my Cell Volt Min brick ID coincidentally happens to be 108! …
April 2023 Model 3 RWD Made in China 60.5kWh LFP pack.What car, battery and make?
The 55kWh CATL LFP had 106S (quite sure, I think Sandy Munroe & co had a pack apart and said 106…)
108 would make sence…60kWh pack?
I agree. Same as NMC/NCA. I don't know what the guy in the video is talking about when he says there is a 5% top buffer, it makes no sense.I guess you agree that according that post and voltages there is no upper buffer and the cells are actually charged to 100%?
This looks correct - it appears that Tesla are happy to push the cells to 3.8V.The max pack voltage is 410V according to the BMS, this implies that the pack is allowed to be pushed to 410V (3.8 V/cell).
Max pack voltage has been correct on all cars i tested. I’m sure it does not mean to charge until the pack has 410V OCV…
The usual misunderstanding.when he says there is a 5% top buffer, it makes no sense.
Yes, thats my take / guess.It could alternatively be plausible that they allow 3.8V during short term regen events - they may have determined that this doesn't have significant ill-effect. I would have to do some serious testing to work this out!
Yes, If we charge to 100% and accererate, there would be space in the pack energy wise to regen that energy back - but for the NCA/NMC they are so close to the maximum voltage that virtually no regen power can be pushed except exceeding the maximum voltage, even if there is space for the e ergy itself.If you took it to the extreme and charged to 100% at the top of a mountain and then pointed the car down hill to regen all the way down, I think it would reach a point pretty quickly where it would prevent any further charge. It would be interesting to try this while watching SMT - need to find a charger on a mountain first! (And check the brake fluid).
I have seen the regen produce a little power when the battery was too cold (MSP) and the regen lower seemed to match the power needed to heat the cabin etc.I also don't know if it would try to dump energy via the heat pump and stator windings to still provide some "simulated regen" to maintain the single-pedal-driving effect. In theory it could, but I don't know if it's designed to do that.
The stators have been using 3kW each at least before.When pre-conditioning for supercharging, my RWD will use up to 8kW to heat the battery - some of that is the heat pump but I think most of it is via the rear stator winding. That could be 8kW of dump capacity for "simulated regen".
Have to turn that option on.assume it does start to blend in the brakes