New RWD LFP ideal SC strategy?

[crazy150]

Just got my RWD a few days ago and tesla is taking their sweet ass time shipping me a charger for it to use at home. <rant>I get keeping costs down by not including the charger and floor mats for people that don’t need/want them, but then at least stock these things so they are delivered with the car for those that want to pay for them<\rant>

So while I wait, I’m just planning on charging at the closest SC which is an 3 mile (11 min) drive away. I know the LFP battery can routinely be charged to 100% but I also know that the charge rate slows quite a bit at the end. I don’t have any experience at the low end, but prolly gonna get some range anxiety under 20-30%.

So what’s the ideal strategy just to keep the battery at a good level with minimizing charge time?

Specifically, what SOC would be good to start and end a super charging session just to get an extra 100mi or so since I only drove about 100-200mi per week.

 

[3sr+buyer]

In general, start at as low a state of charge as you can without range anxiety in order to get the fastest charging rates.

 

[theothertom]

That's a tough one. The reason you need to charge to 100% is because there's not much difference in voltage between fully charged and discharged. This means it's hard for the BMS to get an accurate voltage reading, which means it's hard to predict range. I'd start by charging to around 80%. If that works for you, then keep doing it. If not, you'll have to charge higher.
Note that you don't have to use a Tesla level 1 or 2 charger. You can get a charger with a J1772 plug on Amazon and use the adapter that came with your car to charge.

 

[crazy150]

That's a tough one. The reason you need to charge to 100% is because there's not much difference in voltage between fully charged and discharged. This means it's hard for the BMS to get an accurate voltage reading, which means it's hard to predict range. I'd start by charging to around 80%. If that works for you, then keep doing it. If not, you'll have to charge higher.
Note that you don't have to use a Tesla level 1 or 2 charger. You can get a charger with a J1772 plug on Amazon and use the adapter that came with your car to charge.

Thanks for the reply. I read a lot about the suggestion to charge to 100% at least once per week. Iirc that’s only for prediction and not for any actual condition of the battery right?

As for the charger, yes I understand a generic one will work but I already have the Tesla one on order and just got the shipping notice tonight so hopefully will be here soonish.

 

[DuncanM]

Just got my RWD a few days ago and tesla is taking their sweet ass time shipping me a charger for it to use at home. <rant>I get keeping costs down by not including the charger and floor mats for people that don’t need/want them, but then at least stock these things so they are delivered with the car for those that want to pay for them<\rant>

So while I wait, I’m just planning on charging at the closest SC which is an 3 mile (11 min) drive away. I know the LFP battery can routinely be charged to 100% but I also know that the charge rate slows quite a bit at the end. I don’t have any experience at the low end, but prolly gonna get some range anxiety under 20-30%.

So what’s the ideal strategy just to keep the battery at a good level with minimizing charge time?

Specifically, what SOC would be good to start and end a super charging session just to get an extra 100mi or so since I only drove about 100-200mi per week.

An inexpensive J1772 charger and Tesla adapter is a very cost effective method for L1 and L2 charging and I use an L1 J1772 EVSC for charging at our underground condo parking stall, and another 16amp L1/L2 J1772 EVSC for use at our winter home via a NEMA 5-20 outlet (= 16amp at 115v), although I intend to add a NEMA 6-20 outlet in the near future. My M3 came with a Tesla L1/L2 EVSC, but I keep it in the car for use whilst away from home.

Based upon user reports (including mine), the M3 LFP battery doesn't seem to mind being charged to 100%, even on a daily basis.

20-30% SOC = ~50 to ~90 miles of range, however this prediction is based upon the BMS knowing the true SOC, but if you SC to 100% on a weekly basis you should be fine. The M3 LFP charges very fast even at high SOCs.

 

[XPsionic]

In your situation, go at the end of a drive before you head home, hopefully on a low state of charge, like less than 20%. Plug in for like 15 minutes or until you get bored.

Car charges a lot faster if you 1. have low state of charge 2. battery is warmed up after driving for a while 3. battery is really warmed up by navigating to the supercharger station for at least 15 minutes before you get there

As for the 100% thing, I wouldn't worry about it for now, sounds like your home charging cable's coming soon.

 

[lowercase]

Supercharge to 80 or 90% and then top up to 100% using an L2 somewhere with the J-plug adapter.

 

[Regaj]

Yes, the LFP-charge-to-100% is only for the BMS. I wouldn't worry about trying to charge to 100% - especially at a SuperCharger. Plenty of time for that once your charger arrives.

LFP's exhibit less cell stress from the higher voltages that come with higher SOC's. But they are in no way immune to the other downsides of DC Fast Charging. So the same advice applies as to all EV's... use SC's as much as you need, but no more.

In the OP's situation, I'd probably charge to about 80%. Since you're so close to the SC, it would be good to Nav to the SC 30 minutes or so beforehand so the battery can pre-heat.

 

[crazy150]

Yes, the LFP-charge-to-100% is only for the BMS. I wouldn't worry about trying to charge to 100% - especially at a SuperCharger. Plenty of time for that once your charger arrives.

LFP's exhibit less cell stress from the higher voltages that come with higher SOC's. But they are in no way immune to the other downsides of DC Fast Charging. So the same advice applies as to all EV's... use SC's as much as you need, but no more.

In the OP's situation, I'd probably charge to about 80%. Since you're so close to the SC, it would be good to Nav to the SC 30 minutes or so beforehand so the battery can pre-heat.

So if I’m say 15 mins from SC, I can just use the Tesla app and “send to car” which will trigger preconditioning to start maybe 10-15mins before I leave?

 

[crazy150]

So today was charge day. I was going to charge from 29-80% but my kid was entertained so I just let it go a bit longer to 89%.

I have to say, the whole SC experience has been great so far. Only took 18 mins to add 100miles which is actually very reasonable as that may least me 5-7 days.

 

[Regaj]

So if I’m say 15 mins from SC, I can just use the Tesla app and “send to car” which will trigger preconditioning to start maybe 10-15mins before I leave?

No, "Scheduled Departure" from the smartphone app will bring the cabin temp to whatever you've set. And if the battery is cold enough - probably never going to happen in Southern Florida - it will pre-heat the battery just enough to get it out of really cold zone. But the pack temperature needed/desired for Supercharging is much, much higher. AFAIK the only way to trigger that is to go into your Nav system in your car and punch up the Supercharger location there.

Probably a moot point anyway, since it sounds like you should have your charger very shortly. And, yeah, the Supercharger experience is pretty cool, isn't it?

Congrats on the new car!

 

[crazy150]

No, "Scheduled Departure" from the smartphone app will bring the cabin temp to whatever you've set. And if the battery is cold enough - probably never going to happen in Southern Florida - it will pre-heat the battery just enough to get it out of really cold zone. But the pack temperature needed/desired for Supercharging is much, much higher. AFAIK the only way to trigger that is to go into your Nav system in your car and punch up the Supercharger location there.

Probably a moot point anyway, since it sounds like you should have your charger very shortly. And, yeah, the Supercharger experience is pretty cool, isn't it?

Congrats on the new car!

I thought if I “send to car” the SC location it will navigate to the SC and therefore will precondition? If not is there no way to trigger this from the app?

 

[Regaj]

@crazy150, your post prompted me to look at my app... and as you already knew... there it is. I didn't know the Tesla app had a "Send to Car" feature.

Yes, I'd think that would trigger the SC-level pre-heating just fine.