Incorrect battery percentage reading and range estimation

[yogi799]

Sorry, accidentally posted in the wrong section..

Here is the situation: If I have "burned" 40kwh on a 60khw battery, as shown below, with the usable battery power of 57.5 kwn, first of all, why doesn't the display show 33% left rather than 11%? That suggests that i had roughly 17 kwh left in the packs, which at my consumption would yield another 80 km or range or 265 km in total (acceptable winter range). The nav told me I will NOT make it home which was only 45 kmh away, and i would be at -7% battery at home, so... what gives? Such a HUGE difference suggests only one thing, that tesla builds in a TONNE of reserve range.... Is that true? Is it reasonable to assume that with the computer showing 0%, I would easily make it home by driving another 20 km? (again , home was 45 km away and math suggested 80 km left in the battery) OR am i mistaken about the hidden reserve range at zero and there is some incorrect, not very precise math/chemistry going on in the battery packs and I have indeed used a lot more than 40 Kwh in the 185 km covered?

Dying to know what gives... As it is, the math doesn't add up AT ALL!

 

[GtiMart]

The "since charge" indicator only includes energy burned while driving. All energy spent at other moment, in park, conditioning the cabin, etc, is not included. Your battery indicator (11% here) is the real indication of the energy left in your battery.

 

[yogi799]

Oh wow, that's great to know, so I guess that solves the mystery. So 20% was used on cabin Heat heated steering wheel and heated seats? Gee if that's the case I have never anticipated it to matter so much

 

[GtiMart]

Heating while you are driving IS included. However, if you pre-heat before leaving, if your car doesn't sleep properly, if you sit in the car with heat on while waiting for someone, that is not included.

 

[yogi799]

Sure, but 20%? That is a massive amount of power (ie. equivalent to pushing the car forward for 100 km!). How can that much be used on heating while standing...

 

[Watts_Up]

You should use the Scan My Tesla phone App to get a better idea of you battery SoC, Cells voltages, ....

 

[GtiMart]

You haven't told us what you did apart from driving. It's possible to burn through the whole battery without driving a single kilometer if you want to. Same thing on an ICE, you could let it idle and burn the whole tank without going anywhere. You can't just think of the battery in terms of kilometers. It holds energy (which we count as kWh), not kilometers.

 

[Unclepaul]

Estimates are just that...estimates. What you are doing with the car can make a huge difference in energy consumption. Same with heating your house. Sometimes turning up the thermostat 10 degrees can double your bill. Flooring the throttle at every start can increase tire consumption considerably.

 

[Benito1283]

Oh wow, that's great to know, so I guess that solves the mystery. So 20% was used on cabin Heat heated steering wheel and heated seats? Gee if that's the case I have never anticipated it to matter so much

Go to the energy app and it will tell you how much battery was used for different things.

 

[Supcom]

Was this battery fully charged before the trip?

 

[yogi799]

Yes fully charged. Car was sitting outside , heated the cabin 5 minutes before each trip (no more than 10 trips in total). Sentry mode was enabled once overnight. that's basically it. used heated seats, steering wheel while driving. the 185 km distance was done in 36 hours, so not like sitting for a week etc. Just one overnight. It was around freezing temp

 

[Supcom]

Yes fully charged. Car was sitting outside , heated the cabin 5 minutes before each trip (no more than 10 trips in total). Sentry mode was enabled once overnight. that's basically it. used heated seats, steering wheel while driving. the 185 km distance was done in 36 hours, so not like sitting for a week etc. Just one overnight. It was around freezing temp

Sentry mode consumes 7% per day, so factor in the fraction of 24 hours your car was in park on sentry mode. 12 hours would be about 3.5%. Sentry mode does not permit the car to go into sleep mode.