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Chuq
Active Member
"Cold weather" refers to the kind of extreme sub-zero temperatures they get in Canada and Norway. Australia's "cold weather" is no issue. I'm in Tasmania and the biggest impact weather has had on my range was when I was in New South Wales with heavy rain and strong headwinds. Ambient temperature was about 15 degrees which is fairly average for that time of year. In that case my typical ~370 km of real life range was reduced to ~330 km.
Also it's not that it affects capacity, just that the car uses more energy heating the battery, heating the cabin, and is less efficient due to wet roads and wind resistance.
I see..not that bad..thanks for the info. we have really short summer here in UK.unpredictable weather. last year was our experience of one of the extreme winter -10 and summer 41degrees. again thanks.
I’ll update you next winter when here, in Canada, the temperature can drop until -30!!
Also keen to contribute.
Coming up to my LFP Model Y's first (Australian) winter. In Canberra where I live, coldest weeks are like: overnight dip to -5C, morning peak hour traffic at 0C, and top out at 8-10C during the daytime.
Will watch out for range drops but hard to measure since we don't do a lot of kms.
Coming up to my LFP Model Y's first (Australian) winter. In Canberra where I live, coldest weeks are like: overnight dip to -5C, morning peak hour traffic at 0C, and top out at 8-10C during the daytime.
Will watch out for range drops but hard to measure since we don't do a lot of kms.
But what I'm really curious about is what happens if I don't charge to 100% weekly?
It won't damage the battery right? And it should technically keep batteries in better health.
Sure BMS won't be calibrated - but when I decide to charge to 100% again in the future, would that fix the calibration issue? I don't really need an accurate SoC measurement most weeks as we only do 20kms a day on weekdays, and about 50kms on weekends.
It won't damage the battery right? And it should technically keep batteries in better health.
Sure BMS won't be calibrated - but when I decide to charge to 100% again in the future, would that fix the calibration issue? I don't really need an accurate SoC measurement most weeks as we only do 20kms a day on weekdays, and about 50kms on weekends.
Maximillan
Member
You'll find that once the temperature drops into single digits the car will be more likely to reduce the regenerative braking when the battery is cold.
That is a good question but the point is you're not hurting this type of battery when you go 100% so in the best case scenario you're only saving a little bit of mechanical wear on the connectors if you're not pluging in every day.
johnny_cakes
Member
It depends on what you mean by "hurting" the battery. Charging an NCA battery to 100% won't "hurt" it either, but in both cases (LFP and NCA), calendar aging will increase with higher SoC, and that's why @spades is asking whether it's OK to not charge LFP batteries to 100% weekly.
The question is how often should a LFP battery be charged to 100%. There are only 2 reasons to charge to 100% for LFP (or any other Li battery chemistry)
1) recalibrate the BMS
2)to get the range from a 100% charge.
Does it need to be done every week as part of a routine?
No I dont think so
I think irrespective of the Li battery chemistry charging to 100% SoC will gradually reduce battery life
Just treat it like any Li battery but may be with some recordings of predicted range at certain SoC.
For LFP I think:
1) Do a BMS calibration and record the predicted range at 100% SoC
2) Charge between 40-80% (or whatever your favourite min max Soc is) but try to keep the minimum SoC before charge, and max SoC after charge, the same (to compare apples and apples)
3) Record the predicted range before and after each charge
3) Note any drift in the predicted range over time at those SoC.
4) If there is significant drift between 40% and 80% over time then charge to 100% and record the range when at 100%
If there is significant drift at 100% then do the BMS calibration.
The above basically applies to all Li battery chemistries anyway. However maybe need closer attention in a LFP as BMS may not be as accurate in an LFP.
If course if you could not be bothered with the above (and most wont), then just do what the manufacturer recommends.
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You will find that your estimated range will drop over time if you don't charge to 100% when compared to other cars of the same age. Of course you would need TeslaFi or the like for this, but possibly the total range reported in the car would also be lower. However because you are not going to 100% it makes it a little harder to judge this, could be calender degradation too.
I didn't charge our LFP car to 100% for about a month and my projected range when compared to other M3 on TeslaFi quickly fell. I recall it was about 20km lower at one stage than the others. What I suspect and others in the US also, is the LFP has a dynamic bottom buffer. The BMS will increase the bottom buffer % to give you more 'hidden' range at zero just in case you go deep into the pack. This gives the BMS some insurance against the problem of it not having an accurate reference of the cell voltage, which is the main 'problem' with LFP packs.
When I charged to 100% a few times my total range worked its way back to the other cars on TeslaFi.
Bear in mind that the battery pack isn't degrading quicker but in reality the BMS is doing its job.
Right, ok. So this what I was trying to find out. If I don't charge to 100% for an extended period, range will go down, but the moment I do a few 100% it goes back up again. Are you certain that the battery itself isn't degrading at all, and it's just the BMS that isn't calculating range correctly?
I charge my car to 100 every time I plug it in. I never worry about range. I don’t need to optimize battery health. I enjoy my car. There is no evidence that you’re going to be able to prevent the eventual end point degradation, you’re maybe slowing it for a severe negative which is greatly reduced daily driving range.
If it's going back up, then it's not degradation it's showing, since batteries don't un-degrade.
The LFP battery will not be degrading due to the non charge to 100% so rest easy on that. Calender degradation will occur for all as it can't be stopped.
You probably dont understand how low you need to keep charge state to have a meaningful effect on the battery health. If charging to 100% doesnt reduce your enjoyment of the car, can you explain how optimising battery degredation does?
