LFP charging questions.

[pnguyen1011]

I just bought a 2023 M3 SR LFP battery and I'm seeing a lot of conflicting things about charging. My commute is around 60 miles a day. I've been plugging in the charger every night to 100% as Tesla recommendations are to plug it in even if you don't charge and to charge it to 100 at least once a week.

Should I be charging every night? If so is it safe to do it at 100% every night or should I be setting it to 80-90% and just charge it to 100% once a week.

Should I leave it plugged in every night if I don't charge it?

 

[Soul Surfer]

Tesla themselves, recommend 100% on the LFP. Different technology. Don’t sweat it. Tesla also recommends to always charge it.

 

[3sr+buyer]

Should I be charging every night? If so is it safe to do it at 100% every night or should I be setting it to 80-90% and just charge it to 100% once a week.

Should I leave it plugged in every night if I don't charge it?

It may not make that much difference with LFP batteries, but if you do want to attempt to reduce degradation, you may want to keep it at 70% or lower most of the time, and charge it once per week to 100%, preferably just before your day's driving will use up 30% or more of the charge.

The reason for charging to 100% periodically is so that the BMS (battery management system) can stay in sync with the true state-of-charge. LFP batteries have relatively flat voltage curves (from about 15% to 99+%), so an LFP battery that is charge and used only in the flat part of the voltage curve may allow the BMS' believed state-of-charge to drift away from the true state-of-charge. The worst that could happen is that the BMS (and the driver) believes that there is (for example) 25% left, but then it suddenly drops to 15% as it enters the less flat part at the bottom. Could be an issue if you were planning on making it home or to a charging station needing that 10% that just "disappeared".

 

[Chad and M3]

Hello Tesla driver’s and or enthusiast! I bought my 2023 RWD Model 3 in June, and so far very happy with my purchase! Anyway, right to my point and or question. My M3 came with LFP battery and I just want to know(seeing all the different answer’s, but no answer’s to quite answer my question)is it alright, for example, my car is at 87% charge. They say it’s better to leave plugged in whenever you can, however with that much charge and knowing I’m not gonna be driving a bunch the next day or just in general. For overall battery life, is it okay NOT to charge everyday? I maybe charge at home 3 times a week and out of those 3 day’s I do charge to 100% as specified. Otherwise if it’s at 70% I won’t charge either(I’ve seen comments of treat like a phone battery for long battery life).Thanks
-Chad

 

[Randy-12]

Hello Tesla driver’s and or enthusiast! I bought my 2023 RWD Model 3 in June, and so far very happy with my purchase! Anyway, right to my point and or question. My M3 came with LFP battery and I just want to know(seeing all the different answer’s, but no answer’s to quite answer my question)is it alright, for example, my car is at 87% charge. They say it’s better to leave plugged in whenever you can, however with that much charge and knowing I’m not gonna be driving a bunch the next day or just in general. For overall battery life, is it okay NOT to charge everyday? I maybe charge at home 3 times a week and out of those 3 day’s I do charge to 100% as specified. Otherwise if it’s at 70% I won’t charge either(I’ve seen comments of treat like a phone battery for long battery life).Thanks
-Chad

Charge it of don't charge it, do what makes you happy.
As long as you charge it to 100% every now and then.

I will sometimes go 3 or 5 days without charging.

 

[MikeRTX]

Charge it of don't charge it, do what makes you happy.
As long as you charge it to 100% every now and then.

I will sometimes go 3 or 5 days without charging.

I do the same. I've seen the recommendations about plugging in even if not needed, but that's not convenient for me, so I charge every few days as needed. I do always charge to 100%, since the LFP pack can handle it, and I think it helps keep the battery healthy.

 

[father_of_6]

I do always charge to 100%, since the LFP pack can handle it, and I think it helps keep the battery healthy.

Charging any lithium battery to 100% causes added stress to the battery cells. It definitely doesn't "keep it healthy". The "healthiest" state of charge for a lithium battery is in the midrange, perhaps below 50%. This is conjecture, but definitely the top end and the bottom end are the least "healthy" states for a lithium battery.

Tesla recommends charging to 100% because without it, the battery management system can't correctly determine the state of charge. The LFP battery sees an increase in voltage at the top end, and it's that increase in voltage that the BMS needs to verify state of charge. The non-LFP batteries have a closer to linear voltage curve, so they don't *need* to be charged to 100% for accurate BMS estimates.

 

[3sr+buyer]

Charging any lithium battery to 100% causes added stress to the battery cells. It definitely doesn't "keep it healthy". The "healthiest" state of charge for a lithium battery is in the midrange, perhaps below 50%. This is conjecture, but definitely the top end and the bottom end are the least "healthy" states for a lithium battery.

The bottom end of the state of charge is not an issue for battery health, as long as it does not get drained below 0%.

However, many drivers have difficulty estimating their projected use precisely (and the car's projection on the trip energy screen sometimes errs in either direction), so it is understandable that many drivers do not want to get too close to 0% (even with the hidden buffer on Teslas). For long term parking, vampire drain may be a concern if not plugged in and left at a low state of charge; if plugged in, the lowest charge target is 50% on Teslas.

 

[ucmndd]

The "healthiest" state of charge for a lithium battery is in the midrange, perhaps below 50%. This is conjecture, but definitely the top end and the bottom end are the least "healthy" states for a lithium battery.

No. A lithium battery is perfectly happy and healthy at close to 0%.

 

[kimwin]

I finally understand the reason for charging to 100%, just to make BMS can determine the SoC correctly.