LFP battery - how often is too often to charge?

[Geoau]

How often is too often to top up the charge on a (new) 2022 M3 RWD w/LFP battery?

At the moment we're plugging it back in after even ultra short trips using as little as 1% of the battery. Typically this is twice a day.

It kind of sounds like this is the right thing to do from the Tesla website but it just feels kind of wrong. I wouldn't do it to my phone or other battery based device... Tesla site says "LFP Battery, Tesla recommends that you keep your charge limit set to 100%, even for daily use, and that you also fully charge to 100% at least once per week."

Which is followed by: "Tesla uses lithium ion batteries so there is no memory effect. This means there is no need to deplete the battery before charging. We recommend plugging in as often as possible."

 

[OzMaximus]

Plugging in once a day is ok, but I'm no expert

But yeah I get it if you have solar, and want to top up and soak in all the free electrons

 

[acaurora]

From what I have seen here and around the interwebs, the reason why it is encouraged to always charge to 100% is for the Battery Monitoring System (BMS) to get an accurate idea of the remaining charge on your battery. I could be wrong but my understanding is that the voltage does not change much between near full and near empty for the LFP batteries, and that is what normally is used by the BMS to know your battery's capacity.

I took delivery of my LFP RWD only about a week ago, and I have charged it once so far. I plan to stick with the once weekly 100% charge - my daily commute is only 5 miles, but with sentry mode on while I am at work, and the heaters on during this cold weather, it drains about 5-8% per day, so by the time the weekend comes, should be at 60%, at which point I will recharge either via the free 120V level 1 AC outlet in my garage (approved by management) or going to the level 2 chargers at work.

 

[moa999]

It sounds like you are charging to 100% more than once a week.

Personally I'd probably set the limit to 80-90% and then just charge to 100% every now and then.

 

[brkaus]

I’d plug in every few days. No need for the wear on the connectors and such to plug in and out all the time. Imho.

 

[YAnthony]

LFP is encouraged to be charged to 100% (weekly) so don't confuse with it with other earlier models. I can't talk much beyond that though..

 

[Chuq]

I have a similar usage pattern to you - most of my trips are 2-4%, my standard usage for a whole week is about 50%.

I typically charge to 95% every weekend, either Saturday or Sunday, depending on when I'm home and the sun is out (solar generating).

I'll charge to 100% before a long trip or every ~4 weeks if I haven't sooner.

From what I can work out, the main benefit of charging to 100% is the calibration, which makes your range prediction more accurate, so it's not something I typically need when I rarely get below 50%.

 

[bingbung00]

Model 3 Owner's Manual | Tesla

Learn about your vehicle’s battery and battery best practices.

www.tesla.com

Set the charge limit to 100% and charge as much as you want. Make sure it goes to 100 at least once a week.

 

[johnny_cakes]

It depends on what you're optimizing for.

If you're optimizing for convenience and the joy of owning an EV, charge when you feel like it (similar to what you do with your phone), but just make sure to charge it to 100% once a week.

If you're optimizing for battery health and want to minimize degradation, keep the battery SoC as low as comfortably possible to minimize calendar aging (yes, LFP still suffers from calendar aging, see this), but still charge to 100% once a week. Then read posts from @AAKEE to optimize further.

 

[SteveThompson4]

It’s still a Lithium Ion Battery. it’s not advisable to keep any Lithium Ion Battery charged to, or close to, 100%.
The reason to charge an LFP battery to 100% once a week is to recalibrate the Battery Management System and to balance the charge across all the cells. The voltage of an LFP cell varies very little between 90% and 100%, so the BMS needs an occasional 100% charge to recalibrate.

For what it’s worth, I drive about 250 - 300 Km every day, I charge my LFP battery to 85% every night, except Friday 100% (Saturday is my busy day).

 

[Geoau]

It’s still a Lithium Ion Battery. it’s not advisable to keep any Lithium Ion Battery charged to, or close to, 100%.
The reason to charge an LFP battery to 100% once a week is to recalibrate the Battery Management System and to balance the charge across all the cells. The voltage of an LFP cell varies very little between 90% and 100%, so the BMS needs an occasional 100% charge to recalibrate.

For what it’s worth, I drive about 250 - 300 Km every day, I charge my LFP battery to 85% every night, except Friday 100% (Saturday is my busy day).

Makes sense. I’ve updated ChargeHQ to do exactly this i.e. don’t charge beyond 85% until Fri/Sat evenings

 

[bingbung00]

I would just follow the tesla recommendations.

If you look at the links that others have posted keeping lfp at 85% compared to 100% is basically no difference (~0-2%). Between 20-60% seemed to be a slight benefit ~2%.

Furthermore, wouldn't degradation eventually plateau to the same point in 2-3 years? Seems like a great sacrifice to the convenience of operation. Range is not even important to the operation of your car unless you experience significant degradation well above expected (which would be covered by warranty regardless).

 

[Rocket_man]

I have an RWD with LFP and I charge it to 100% on the weekend and don't charge it during the week. If it is a typical week I'll be around 40% to 50% SoC. Charging to 100% once a week is best for the battery mgt system. Since I also have solar I like to see if I can charge during a sunny day and manage to charge my powerwalls and the car without pulling from the grid. It really doesn't make a difference in cost, just a challenge to do it. Yes under the right circumstance I can do it.

 

[herrlich98]

I wouldn't overthink it. Your Tesla doesn't need a second tier BMS the regular BMS does an excellent job!

Unless it is really a pain to plugin I would just get in the habit of plugging it in when I parked and forget about it. You have a thermostat in your home so you don't have to worry about when to turn on/off the furnace and a BMS to handle the charging of your car. With a Tesla let it become something you don't have to spend extra time thinking about like locking your car as you walk away...

 

[Quickst]

The reason to charge an LFP battery to 100% once a week is to recalibrate the Battery Management System and to balance the charge across all the cells. The voltage of an LFP cell varies very little between 90% and 100%

When you looks at a voltage graph of a LFP with battery voltage on vertical axis and battery state of charge on horizontal axis, then there is a steep drop when battery charge initially drops from 100% and also at the other end towards 0%. But the middle section the battery voltage does not change much as the state of charge drops so it’s difficult for the BMS to accurately predict SOC in the middle section . The voltage which most accurately predicts SOC is when V is around 3.6V for LFP which is when SOC is 100%.

The voltage of an LFP actually changes a lot between 80 or 90 to 100%. The slope of the Voltage/ SOC graph is steepest here.
Charging to max voltage allows BMS to recalibrate the range because that is the only place where SOC is accurately known

The LFP max voltage is lower than the Nickel based batteries used for the LR models. Generally Li batteries at higher voltage tend to lose capacity than batteries at lower voltage. So LFP has an advantage in this regard - (to the extent that V plays a part)

 

[Quickst]

I should say that , the Voltage graph is similar for all Li batteries whether Li-Ni or LFP. They all have a flat bit in the middle. Though the LFP batteries have a much more pronounced uptick in V when the SOC approaches 100% and is slightly flatter in the middle.

Here is a screenshot from a research article:

 

[ARMARM]

Always Be Charging

 

[Quickst]

Always Be Charging

I wonder though, if LFP owners use the trip counter to measure actual distance travelled and only charge to 100% when the vehicle has travelled say half the predicted distance, whether the battery deterioration can be mitigated..So maybe not every day, but every few days or however long it takes to get to half of the predicted km. And at least once a week. \

In other words does charging frequency closer to once a week rather than once or even twice a day extend battery life?

Even for LFP charging to 100% is never good for the battery - because in the end it is still a Lithium ion battery. Tesla only recommends charging to 100% because the BMS only accurately predicts SOC and therefore range, when the voltage is maximum.

 

[Matteo Pedalà]

How often is too often to top up the charge on a (new) 2022 M3 RWD w/LFP battery?

At the moment we're plugging it back in after even ultra short trips using as little as 1% of the battery. Typically this is twice a day.

It kind of sounds like this is the right thing to do from the Tesla website but it just feels kind of wrong. I wouldn't do it to my phone or other battery based device... Tesla site says "LFP Battery, Tesla recommends that you keep your charge limit set to 100%, even for daily use, and that you also fully charge to 100% at least once per week."

Which is followed by: "Tesla uses lithium ion batteries so there is no memory effect. This means there is no need to deplete the battery before charging. We recommend plugging in as often as possible."

Me too i am looking at the same info. I got the new Model 3 with LFP since a week. My daily commute is 100km and I use 12-13% of battery for each leg (considering the weather climate in Canada around 0 deg Celsius). I have recharged to 100% once as of today. I have a level 2 charger at home and one available at work also. Tesla though recommends “at least once a week charge to 100%”. I am really not sure if I should keep the battery charged to 100 all the time since between work and home I have this possibility

 

[Jsch223]

Me too i am looking at the same info. I got the new Model 3 with LFP since a week. My daily commute is 100km and I use 12-13% of battery for each leg (considering the weather climate in Canada around 0 deg Celsius). I have recharged to 100% once as of today. I have a level 2 charger at home and one available at work also. Tesla though recommends “at least once a week charge to 100%”. I am really not sure if I should keep the battery charged to 100 all the time since between work and home I have this possibility

My commute is similar. I charge to 85% every day but Thursday. Charge to 100% on Thursdays to keep the BMS calibrated. I’ve lost 1 mile of range in my first 3000 miles.