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LFP battery, charge to 100% each night?
- Thread starter BrianScott1980
- Start date
I know it's not physically, but I think of the battery as a tank full of fuel. If it costs me say 100 quid to fil it up, but if I only ever empty half of it before refilling then I have over spent to what I actually need by 50 quid.. It comes back to only charging what you need plus a margin. So while the values are different the principle will be the same.
The display doesn't have the 90% marker
I don't charge my (non LFP) to 90% every day, just keep it to between 40 and 80% generally and charge more when needed and I see no reason why you wouldn't do the same. The M3, certainly the none LFP batteries, benefit from being left over night at lower states of charge so the BMS can get accurate readings across the range to calibrate. Then on the days when you need the extra range then fully charge. For you 100 is the new 90. It has been recommended a periodic 100% charge is good for it so maybe once a month, just like its a good idea to leave it below 50% once a month for calibration.
I don't charge my (non LFP) to 90% every day, just keep it to between 40 and 80% generally and charge more when needed and I see no reason why you wouldn't do the same. The M3, certainly the none LFP batteries, benefit from being left over night at lower states of charge so the BMS can get accurate readings across the range to calibrate. Then on the days when you need the extra range then fully charge. For you 100 is the new 90. It has been recommended a periodic 100% charge is good for it so maybe once a month, just like its a good idea to leave it below 50% once a month for calibration.
Drew57
Active ember
Fill a fuel tank to 50%, leave untouched for a month at any time throughout the year & it still has 50%
Fill a Model 3 to 50%, leave untouched, asleep for a month in (ie) late summer & it has around 40%
Fill a Model 3 to 90%, leave untouched, asleep for a month in (ie) late summer & it has around 80%
ie in both scenarios it has drained by a similar percentage. This is based on my own experience last August and September.
The only reason I would normally leave at a lower state of charge is when I anticipate either a sunny day (excess solar generation), a trip using a Supercharger (currently have a lot of miles remaining) or maybe a long stay at a supermarket, local zoo or shopping centre (free charging).
As for BMS calibration, I do that occasionally but is that just allowing more accurate prediction of range rather than actually increasing range in some way?
I only focus on battery %, never miles as the LR always has enough range for anything I might need & if I have a longer unexpected journey, the supercharger network and on-screen navigation prediction covers that.
I pretty much leave my M3P (non MIC) around 50%, unless I’m going somewhere at which point I’ll charge it up to whatever I need the night before. Highest I’ve charged it to is 85%, I think.
The downside of my limited miles and journeys is that I don’t think the BMS has any real idea how far my car can actually go.
The downside of my limited miles and journeys is that I don’t think the BMS has any real idea how far my car can actually go.
E
Exactly. I’ve read all the advice to date on the previous battery types. This new type which I now have in my car, I’d like specifics on how it behaves and how I should use / maintain it.
When the battery reaches whatever level is deemed to be 100% (irrespective of whether that is actually 1000% or only 98%) the battery management system will not allow any more electrons to be added to the battery - whether by a plugged in charger or by the onboard regen charger.
That’s a completely reasonable hypothesis but it would actually be possible to allow regen charging beyond the buffer if the system was designed that way. I do agree that it’s most likely the cars are the same as the rest of us with a brief period of no regen at 100 %. We have several people who have sr+ Cars with the lfp battery packs so the question of whether they get regen at 100% can easily be answered.... if only someone would tell us!
I think there is no harm doing so, it seems some things have been floated about doing 100% once a week or so, but I wouldn't do 100% regularly, if nothing else you won't get regen braking for the first part of your journey. At the moment with hardly travelling on my non LFP battery, I have my limit to 50-60%, and up that as and when I need it.
So, I have a MIC SR+, I can comment. It can definitely charge to 100% via the charging scale on UI. My question is related to whether it’s recommended not to. Not opinion, but actually recommended practice. There’s no indicator for trip vs daily etc on the new charging screen for LFP. I’m therefore curious to know if that means there’s no longer a need to think of charges for longer routes vs regular charging to 100% and therefore getting the max range possible when setting out each day.
I don't think anyone has a definitive answer. Clearly 100% will be much less of an issue for you so you can indeed maximise your range more effectively. I think all that people are saying meantime is that if you know there isn't a chance of needing more than 100miles next day why put 100% in the battery. Those of us with the other type of battery find that at 100% we have a period without regenerative braking. Is that the case for you? On our cars there's actually a warning pops up on the screen warning that there will be no regen available when you first start out if charged to 100%. When you are used to regen braking it's a bit of a pain to be without it so that alone may suggest 95% is a better option. So ... does your car have regen when at 100%?
geek1975
Member
I have charged my MIC LFP SR+ to 100% each charge (weekly so far as not driving much). Each time I have still had regen, even at the start of my 3 mile “commute”.
I have seen the ”reduced regen” warning, but I still had that this morning and again this afternoon when I started with a 75% SoC on the battery, so I’d suggest that’s more to do with the battery being cold (it being lower that 7 deg C for my drive home).
a1psx
Member
I've charged our i3 to full for a long time (since it has a small battery) - after 5 years it's still got the same range - doesn't the 'buffer' they add to the battery at new cope with the degradation over time? I'm picking up a MIC SR+ on weds - and I doubt I'll change our charging behaviour, especially as I imagine we'll be getting a new one in a few years.
Regarding the regen braking - the i3 didn't brake much or at all when it's battery was full and sometimes would feel like it was running away when you lifted the accelerator as you do get used to the auto braking. You get used to this and expect it after fully charging.
Regarding the regen braking - the i3 didn't brake much or at all when it's battery was full and sometimes would feel like it was running away when you lifted the accelerator as you do get used to the auto braking. You get used to this and expect it after fully charging.
Yes that’s the regen behaviour we see with the model 3 at 100%. Different manufacturers use different buffers so the sensitivity about charging to 100 is less, which is why we are trying to get a handle on how the LFP pack behaves. Tesla have said to some people that 100 is fine but we are trying to clarify if it’s still advantageous to put in a lower percentage or is that now a thing of the past.
I also have a March 21 MIC and couldn’t give a stuff about degradation. I charged my car to 100% each night and on day 10 with 270 miles covered I got a pop-up saying to reduce the charge level. Now set at 90%, I’m doing minimum mileage and popping out for fun only. I also intend keeping my car a long time unless Tesla will let me port my FSD to a new car they’ll have lost my business for sure.
The car prompted you to charge at lower than 100% ? Which software version are you on ?
I have a Dec 20 MIC with LFP battery and been charging at 100% for the last couple of months and never got this pop-up message.
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