Charging habits

[yessuz]

FWIW TeslaFi shows "your car" and "fleet" for comparison

but the battery comparison accuracy directly depends on data accuracy

 

[init6]

Teslafi and Teslamate use the same guesses as to battery health. Teslafi just compares it with other guesses using the same method.

 

[GeorgeSymonds]

Teslafi and Teslamate use the same guesses as to battery health. Teslafi just compares it with other guesses using the same method.

I saw a breakdown somewhere but I think the basic approach is

- from the last charge, work out the efficiency from rated miles added and kWh added - so the bigger the last charge the more accurate it’s likely to be as it reduces rounding wrrors

- using the efficiency x rated miles available tells you how much energy you have stored. Not sure if that’s temperature dependant or not

- divide by the state of charge gives total energy that can be stored

And then as suggested, what’s the starting point given the same model of car can have different batteries?

Then add the number you first though of.

Having said that, you can clearly see a downward trend but it would be interesting if seasonality plays a part (ambient temperature) or size of last charge (rounding) or country and age (clue to battery). But then things start getting pretty complicated and people just want a % figure

 

[WannabeOwner]

the bigger the last charge the more accurate it’s likely to be as it reduces rounding errors

FWIW TeslaFi has a filter, so you can choose to only include, say, 100% charges or 99%+ charges

what’s the starting point given the same model of car can have different batteries?

TeslaFi decodes the "options" API data, dunno if that distinguishes Battery Version? But if so it could aggregate only "fleet members" that match.

There is stuff in there for "similar mileage / age" too (not looked at it recently, so this is from memory)

 

[init6]

I saw a breakdown somewhere but I think the basic approach is

- from the last charge, work out the efficiency from rated miles added and kWh added - so the bigger the last charge the more accurate it’s likely to be as it reduces rounding wrrors

- using the efficiency x rated miles available tells you how much energy you have stored. Not sure if that’s temperature dependant or not

- divide by the state of charge gives total energy that can be stored

And then as suggested, what’s the starting point given the same model of car can have different batteries?

Teslamate does mention the importance of getting good data at the start of the car's life. As you say what you start with is probably the biggest factor on how much you have left.It does give you the option to specify your starting point.

This dashboard is meant to have a look of the Battery health based on the data logged in Teslamate. So, the more data you have logged from your brand new car the better.

**Degradation** is just an estimated value to have a reference, measured on **usable battery level** of every charging session with enough kWh added (in order to avoid dirty data form the sample), calculated according to the rated efficiency of the car.

They're all based on the mythical efficiency figure which as you say George, varies considerably with season.

 

[init6]

TeslaFi decodes the "options" API data, dunno if that distinguishes Battery Version? But if so it could aggregate only "fleet members" that match.

Can you see the battery version for your car in Teslafi anywhere?
I'm sure there has been a lot of discussion in the past about battery versions, so I would have thought if it was there the discussions would have been a lot shorter.

 

[kelvin 660]

I'm using TeslaFi and Scan my Tesla to try and determine battery health but the results don't actually agree with each other. According to SmT the battery has degraded by 6.5% whereas TeslaFi uses the range at 100% SoC and it has determined that the battery has only degraded by 4.7%.

So which one is correct? And how accurate is the BMS that acutely provides these numbers? Can anyone shed some light of how the BMS actually works out these numbers?

Cars age in years	0​	0.5​	1​	1.5​	2​
Nominal Full Pack kW/h - SmT	55.1​	53.0​	52.6​	51.9​	51.5​
Battery reduction kW/h - SmT	0.0%​	3.8%​	4.5%​	5.8%​	6.5%​
Miles @ 100% shown by car	263.49​	260.98​	257.07​	255.51​	251.22​
Miles reduction	0.0%​	1.0%​	2.4%​	3.0%​	4.7%​

 

[WannabeOwner]

I would have thought if it was there the discussions would have been a lot shorter.

I agree, and my recollection of such threads was along the lines of "I've crawled under the car and looked at the sticker-label on the battery"

 

[WannabeOwner]

which one is correct?

Car may have some "reserve" which it allocates as battery range deteriorates - which will fool TeslaFi (comparing journey distance travelled from 100% charges) into thinking little / no degradation. Whereas, I presume, Scan-my-Tesla is looking at some actual data in the BMS?

 

[init6]

They're all right. They're all guesses.

 

[ACarneiro]

I thought around 10% degradation in the first 2-3 years was expected?