250wh per pile to get performance rated range of 315 miles

[David99]

I don’t get why everything is an estimate though why can’t just give the actual state of charge

If it’s at 70% and it tells me well we think it’s at 65% don’t do that just tell me it’s 70%

This would also tell you how much the battery has degraded if it won’t full charge anymore

Energy in a battery isn't like liquid in a tank. It isn't a absolute amount. A cold battery has higher internal resistance so you will get less energy out of it, the rest is lost. If the same battery with the same state of charge is warm, you get more out. That's just how batteries work. Tesla cars know all about the battery conditions and tell you the best possible number based on all these. I know this sounds counter intuitive and we really want it to be as simple as water pitcher that holds exactly x amount of water, but that's just not how the chemistry in a battery works. It is a number that will fluctuate up and down a bit in a way that appears random to us. The BMS knows way more than we do.

Having driven 3 Tesla vehicles over the last 10 years and a total of over 500k miles, I can speak from experience, Tesla's battery management and range estimates are pretty good.

 

[gottagofast]

My understanding is that measuring the pack voltage is not an exact thing. As such, you will always get an estimate.
In addition, the car can’t ‘know’ exactly how you are going to drive, and in what environment.

If you want the nitty gritty, check out the energy graph. It will give you a silly amount of information about where the energy was used on your drive. It will also give recommendations on how to lower your energy use.

In the end, I echo the suggestions to just drive the car and enjoy it, once you have satisfied you curiosity,

It tells me the exact amount of kWh that I put into it when it charges, it’s odd that it can’t tell me the kWh that have gone out

 

[Zcd1]

My understanding is that measuring the pack voltage is not an exact thing. As such, you will always get an estimate.
In addition, the car can’t ‘know’ exactly how you are going to drive, and in what environment.

Exactly.

 

[Zcd1]

It tells me the exact amount of kWh that I put into it when it charges...

Actually no it doesn't tell you how much energy actually makes it into the battery because of "charging losses", but that's a whole other rabbit hole that's not worth going down...

 

[David99]

It tells me the exact amount of kWh that I put into it when it charges, it’s odd that it can’t tell me the kWh that have gone out

When you charge, the car can measure very very accurately how much energy is going though. How much the battery is able to absorb and how much it will later be able to give is a different story. As I said in my earlier post, there are many factors that affect the chemistry in the battery to work better or worse. The amount goin in and going out is not necessarily the same.

 

[Zythryn]

It tells me the exact amount of kWh that I put into it when it charges, it’s odd that it can’t tell me the kWh that have gone out

Here is an article that spells it all out rather well.
It is a bit old, but still applies.

The challenges of battery state of charge measurements - Charged EVs

Your BMS’s fuel gauge is lying to you. Here’s why that’s not a big deal. Battery management systems (BMSs), and the fuel gauges in them, are a part of daily life for almost everyone. You’ll find them in vehicles, laptops, cell phones, grid-attached energy storage – basically, anything that does...

chargedevs.com

 

[gottagofast]

I also heard it’s good to charge to 100% like once a month to balance the cells or something?

 

[E90alex]

I also heard it’s good to charge to 100% like once a month to balance the cells or something?

Not necessary

 

[ZenRockGarden]

Oh if they are both estimates I’ll just leave on miles, I wish there was an actual kWh reading

Wait till he finds out that his gas gauge is also an estimate and when it says "empty" it's not actually empty it's got another gallon to go

 

[gottagofast]

I was able to get 248wh/mile today not sure what I did different, I even had ac running half the trip

Still not sure why I lost 12 miles of range while being parked though, that seems so random to me it stayed at 171 after those 4 hrs and didn’t lose anymore after that, maybe it was charging the lithium 16v or something?

 

[ZenRockGarden]

I was able to get 248wh/mile today not sure what I did different, I even had ac running half the trip

Still not sure why I lost 12 miles of range while being parked though, that seems so random to me it stayed at 171 after those 4 hrs and didn’t lose anymore after that, maybe it was charging the lithium 16v or something?

Ambient and battery temperature are biggest factors (assuming you do a loop and are not including elevation change). Headwind, Rain and tire pressure are next on the list.

But yes, if you drive like an EPA grandma at a steady 60 MPH (or less - the EPA actually averages a pathetic 45 mph) you should see use in the 220 to 250 wh/mi and easily hit rated range. Add 25 wh/mi for every additional 10 mph-ish above 60. It's that simple

The go set your display to read battery-percent and treat the car like an iPhone. Plug it in when low.

 

[gottagofast]

Ambient and battery temperature are biggest factors (assuming you do a loop and are not including elevation change). Headwind, Rain and tire pressure are next on the list.

But yes, if you drive like an EPA grandma at a steady 60 MPH (or less - the EPA actually averages a pathetic 45 mph) you should see use in the 220 to 250 wh/mi and easily hit rated range. Add 25 wh/mi for every additional 10 mph-ish above 60. It's that simple

The go set your display to read battery-percent and treat the car like an iPhone. Plug it in when low.

I tried driving like a grandma before to see if could the rated range and it still failed though lol, I didn’t change anything this trip and got the WH I needed

 

[Kevy Baby]

I tried driving like a grandma before to see if could the rated range and it still failed though lol, I didn’t change anything this trip and got the WH I needed

Try driving a steady 40 MPH and you should see the difference

But who the heck wants to do that?!?

 

[gottagofast]

Try driving a steady 40 MPH and you should see the difference

But who the heck wants to do that?!?

Im just experimenting trying everything with the car, I already did 0-60 a few times now I’m trying to get the rated range

 

[ZenRockGarden]

I tried driving like a grandma before to see if could the rated range and it still failed though lol, I didn’t change anything this trip and got the WH I needed

tell us you're not driving using the brake pedal?

 

[David99]

I also heard it’s good to charge to 100% like once a month to balance the cells or something?

The BMS balances the cells at any state of charge. The battery chargers used in RC toys use 'top balancing'. They charge the battery until full and then balance the cells to make sure all are equally full. It's a very old and method from the early days. The BS in an EV is much more sophisticated. It doesn't need to charge to 100% to balance.

There is a reason why you should once in a while charge close to 100% and drive down very low. There is no possible way to measure accurately how much energy is left in a battery. The BMS has all kinds of data and keeps track of how much went in and out. But it's not perfectly accurate. At around 50% the BMS the least accurate. Near the top and and the the bottom end, the data from the battery allows for a more accurate estimate. If you never charge your car near full nor let it drop low, the BMS has to work from less accurate data for a long time and the errors can add up. It can get less accurate. Once you charge close to full or drive very low, the BMS gets more accurate data again and can basically 'recalibrate' itself. Keep in mind, the BMS can get a little less accurate with it's estimate. It is not the battery that gets looses some capacity or gets lazy or anything like that. Charging high and then driving low doesn't condition the battery. The battery is always fine. It;s just the BMS losing some of it's accuracy.

 

[N54TT]

All this talk about trying to get 250 wh/mile on a performance model 3….my 2018 has 74k and a lifetime of 320 wh/mile. I would love to even get under 300 lol.

 

[gottagofast]

tell us you're not driving using the brake pedal?

I use them a little bit to prevent the rotors from rusting, the previous owner didn’t use his brakes at all going by the rust on the rotors

 

[gottagofast]

The BMS balances the cells at any state of charge. The battery chargers used in RC toys use 'top balancing'. They charge the battery until full and then balance the cells to make sure all are equally full. It's a very old and method from the early days. The BS in an EV is much more sophisticated. It doesn't need to charge to 100% to balance.

There is a reason why you should once in a while charge close to 100% and drive down very low. There is no possible way to measure accurately how much energy is left in a battery. The BMS has all kinds of data and keeps track of how much went in and out. But it's not perfectly accurate. At around 50% the BMS the least accurate. Near the top and and the the bottom end, the data from the battery allows for a more accurate estimate. If you never charge your car near full nor let it drop low, the BMS has to work from less accurate data for a long time and the errors can add up. It can get less accurate. Once you charge close to full or drive very low, the BMS gets more accurate data again and can basically 'recalibrate' itself. Keep in mind, the BMS can get a little less accurate with it's estimate. It is not the battery that gets looses some capacity or gets lazy or anything like that. Charging high and then driving low doesn't condition the battery. The battery is always fine. It;s just the BMS losing some of it's accuracy.

If there’s no way to know for sure how much charge a battery has how does Tesla know when the battery has degraded 30% for warranty purposes

That makes sense about the battery losing accuracy though if you never charge to 100%

 

[mpgxsvcd]

All this talk about trying to get 250 wh/mile on a performance model 3….my 2018 has 74k and a lifetime of 320 wh/mile. I would love to even get under 300 lol.

Wheels, tires, driving style, and climate make all of the difference. It may not be possible to do it in your particular situation but I guarantee it could be improved from where you are now with a few simple changes.