EV general discussion

AnastieByte said:
I've been trying to do man math's to compare annual cost of running my Toyota Rav4 Hybrid against a possible future purchase of a Tesla M3LR.

I thought on paper the savings would be bigger so I'm asking if I have gone wrong somewhere with my calculations.

Ive taken my annual mileage as 8,000. My Rav4 economy as 45mpg. Ive broken down Insurance cost to monthly and a tyres plus fund for additional expenditure on car.

My calculations are:

Tesla M3LR

Electricity – 8,000 miles a year @9p a kw = £201 per year= £17 month
Tyres plus: £60/month
Tax: €0
Insurance: £55/month:
Servicing: zero

Total: £132/month to drive Tesla Annual Total £1584

Rav4 Hybrid

Fuel: 8,000 miles a year = 22m a day = £1.35 litre = £1.048 per year = £88 month
Tyres plus: £60/month
Tax: from above budget (pay £580)
Insurance: £32/month
Service Plan: £30/month:

Total: £210/month to drive a Rav4. Annual Total £2520 a year

Difference: £78/month or £936/year or £4,680 over 5 years.
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You really need to consider depreciation as a cost of ownership.

Some of those kWh will be more like 50p than 9p too as you are unlikely to do every mile with the cheap electric. Also consider 10% loss for charging and Tesla seem to lose charge overnight. Seems 3.5m/kwh for maths which is probably ok but depends on your route
 
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Simon said:
You really need to consider depreciation as a cost of ownership.

Some of those kWh will be more like 50p than 9p too as you are unlikely to do every mile with the cheap electric. Also consider 10% loss for charging and Tesla seem to lose charge overnight. Seems 3.5m/kwh for maths which is probably ok but depends on your route
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Not heard of 10% loss through charging. Think AC-DC charging isn’t 100% but almost there due to inverter.

But DC-DC is pretty much 100%

Where you getting 10% charging loss from?

Is that 10% degradation? Again that depends on mileage and usage and super charging. ICE car efficiency degrades over time also. He used 3.5miles/kwh which is low end of what M3 can do so quite a conservative efficiency already.

If it is a Tesla the most you should be paying leccy is 35p at super chargers. There are plenty super chargers around which means you shouldn’t be using other chargers.

Out of the 8000 annual miles that is likely to mean nothing. Maybe add extra £30 to the equation.

Then similarly you can argue the ICE car will most definitely need fuel that’s more than £1.35/L as there isn’t a Costco everywhere in the country and unless you live next to a Costco your fuel cost is more likely to be £1.45

He s used best scenario for ICE and EV so it is Apples to Apples.
 
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pc-guy said:
Not heard of 10% loss through charging. Think AC-DC charging isn’t 100% but almost there due to inverter.

But DC-DC is pretty much 100%

Where you getting 10% charging loss from?

Is that 10% degradation? Again that depends on mileage and usage and super charging.

If it is a Tesla the most you should be paying leccy is 35p at super chargers. There are plenty super chargers around which means you shouldn’t be using other chargers.

Out of the 8000 annual miles that is likely to mean nothing. Maybe add extra £30 to the equation.

Then similarly you can argue the ICE car will most definitely need fuel that’s more than £1.35/L as there isn’t a Costco everywhere in the country and unless you live next to a Costco your fuel cost is more likely to be £1.45

He s used best scenario for ICE and EV so it is Apples to Apples.
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Can you stop making stuff up because?

You have just heard of it so how can you say “I haven’t heard of it” ?!

AC to DC rectification at the design threshold will be 85%-92%. Ie 240V 32A.
Anything that lowers of voltage and current will lower the efficiency more.

For DC. The parasitics of 12V hotel loads, pumps and fan, AC compressor and heater and then the physical heat loss on cables means it can’t be 100%!! If you had an EV you would know this from what you get billed from the charger to the cell measured energy in the battery.

Honestly, some of the posters here are beyond jokers, they just lie and make stuff up. Really poor form.
 
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I noticed theres a few subscription services for public chargers, Skoda have the powerpass which is with ionity and for 13.99 a month, you can get fast charging for 44p a unit, so potentially a viable solution for higher mileage drivers.

Anyone any experience of these sub services? seems too good to be true :p
 
pc-guy said:
Not heard of 10% loss through charging. Think AC-DC charging isn’t 100% but almost there due to inverter.

But DC-DC is pretty much 100%

Where you getting 10% charging loss from?

Is that 10% degradation? Again that depends on mileage and usage and super charging. ICE car efficiency degrades over time also. He used 3.5miles/kwh which is low end of what M3 can do so quite a conservative efficiency already.

If it is a Tesla the most you should be paying leccy is 35p at super chargers. There are plenty super chargers around which means you shouldn’t be using other chargers.

Out of the 8000 annual miles that is likely to mean nothing. Maybe add extra £30 to the equation.

Then similarly you can argue the ICE car will most definitely need fuel that’s more than £1.35/L as there isn’t a Costco everywhere in the country and unless you live next to a Costco your fuel cost is more likely to be £1.45

He s used best scenario for ICE and EV so it is Apples to Apples.
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Waste of time replying to most that. Pure conjecture and you have probably never even sat in a model 3. I was trying to help the posters real world maths.

No one charges DC at 9p kWh. So it’s obviously a 7kW AC home charger
 
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Simon said:
Waste of time replying to most that. Pure conjecture and you have probably never even sat in a model 3. I was trying to help the posters real world maths.

No one charges DC at 9p kWh. So it’s obviously a 7kW AC home charger
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I was agreeing with your maths just pointing out.

The other bloke was the one disputing it
 
Currently have the e-niro 4 which is fine car, but my lease is up in Jan 2025 with lengthy delivery times need to look at the replacement, one I have on my list is the Skoda Enyaq, does anyone drive on here and thoughts on it?

I know the standard answer is get a Tesla but have a big dog and while he would fit in the Y its a bit of a drop so I am told from the lip and not sure he would like that.
 
Delivery times aren’t too bad now tbh. I’ve had a 30 min drive in the enyaq and have sat in a ID4. I like both, enyaq is the nicer place to sit, it’s deceptively big. Shame even on top spec ones you don’t get a heat pump as std, or pan roof for that matter.

I prefer the cabin of the EV6 to the enyaq, but the enyaq is a smart looking car in the sport line trim.
 
Tinders said:
Delivery times aren’t too bad now tbh. I’ve had a 30 min drive in the enyaq and have sat in a ID4. I like both, enyaq is the nicer place to sit, it’s deceptively big. Shame even on top spec ones you don’t get a heat pump as std, or pan roof for that matter.

I prefer the cabin of the EV6 to the enyaq, but the enyaq is a smart looking car in the sport line trim.
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One of the guys at board game club has an EV6 keep meaning to ask to have a look in the boot, but its been dark so not helpful.

Didn't know about the heat pump, have that currently and seems to work well for me, compared to the range my Dad gets in the winter as he has one without the heat pump, not too fussed on a sunroof as head pano ones on other cars but never really used it.
 
Jonnycoupe said:
Can you stop making stuff up because?

You have just heard of it so how can you say “I haven’t heard of it” ?!

AC to DC rectification at the design threshold will be 85%-92%. Ie 240V 32A.
Anything that lowers of voltage and current will lower the efficiency more.

For DC. The parasitics of 12V hotel loads, pumps and fan, AC compressor and heater and then the physical heat loss on cables means it can’t be 100%!! If you had an EV you would know this from what you get billed from the charger to the cell measured energy in the battery.

Honestly, some of the posters here are beyond jokers, they just lie and make stuff up. Really poor form.
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just looking at my teslamate stats for efficiency of each charge combined with hypervolt stats for the same charge on AC and a supercharger DC charge

AC charging (5.1 hours @ 7kw at 0.6 Degree C ambient)
36.40 kWh added
37.51 kWh delivered (according to teslamate)
38.84 kWh delivered (according to hypervolt app)
97% efficiency shown in teslamate, but including charger delivered value, 93.7% efficiency

DC charging (supercharger) which reached 205kw peak, 74kw min (8 - 70% SOC)
48.04 kWh added
51.24 kWh delivered (Tesla account shows billed for 51kwh)
94% efficiency

With AC charging, you do have this almost perfect fixed load, so a constant 32A that you can optimise efficiency around, especially with more modern electronics with lower switching losses, and DC is a much more variable load and the parasitic variables as you mention impact on it's theoretical efficiency.

AC Charging session:
1MEZdtih.jpg


DC:
SVwenckh.jpg
 
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Your AC charging isn’t that efficient sorry.

94 maybe I’m not sure how good Tesla is, but for 97 I read first. The apps measuring battery do it predicted on the SoC increments, it’s not using the actual current counter inside the BEM.
 
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Jonnycoupe said:
Your AC charging isn’t that efficient sorry.

94 maybe I’m not sure how good Tesla is, but for 97 I read first. The apps measuring battery do it predicted on the SoC increments, it’s not using the actual current counter inside the BEM.
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The app is actually the (from what it apears) is the Tesla BMS reporting the data..

Teslamate retrieves this via the Tesla API and throws it in a database, and from what I can see in the database, it's getting uncorreleted 'energy added' values alongide 'Usable SoC' values every few seconds, so the 'app' itself doesn't need to grossly infer from SoC itself, just integrate energy added over time.

I am new to Teslamate and the Tesla API, so literally this is the first time I've looked in the DB to see what it seems to be getting from Tesla/The Car directly so happy to be educated.
 
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Im not as close to chargers but Silicon IGBT in the Inverter t Silicon Carbide MOSFETTS is a big jump in efficiency. That is coming for charging retification as China AC efficiency for their drive cycles is based on energy provided from the wall and not just in the cells. The model Y i charged at home at 7kW was around 84% as i charged from empty to full. That said theres a degree of phantom/conditioning that Tesla also uses.
 
Demon said:
Teslamate retrieves this via the Tesla API and throws it in a database, and from what I can see in the database, it's getting uncorreleted 'energy added' values alongide 'Usable SoC' values every few seconds, so the 'app' itself doesn't need to grossly infer from SoC itself, just integrate energy added over time.
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on the slower A/C charging how are those efficiency API figures categorizing the fixed losses from the car electronics systems monitoring the charging, in addition to the invertor itself,
I thought there was 300w or so lost from those systems, which obviously become a become a bigger percentage of total energy from supply, if the car is on a granny charger versus 7.4KW, versus DC.
 
jpaul said:
on the slower A/C charging how are those efficiency API figures categorizing the fixed losses from the car electronics systems monitoring the charging, in addition to the invertor itself,
I thought there was 300w or so lost from those systems, which obviously become a become a bigger percentage of total energy from supply, if the car is on a granny charger versus 7.4KW, versus DC.
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The database has:
battery_heater_on
battery_level
charge_energy_added
charger_actual_current
charger_phases
charger_pilot_current
charger_power
charger_voltage
fast_charger_present
conn_charge_cable
fast_charger_brand
fast_charger_type
ideal_battery_range_km
not_enough_power_to_heat
outside_temp
charging_process_id
battery_heater
battery_heater_no_power
rated_battery_range_km
usable_battery_level

The car/teslamate can seperately track 'delivered power' to the car (charger_power/charger_voltage/charger_current are all fluctuating) and 'charge energy added' direct to the battery, the difference is the losses, electronics and general BMS stuff presumably. Obviously I can also add in what my actual home charger thinks it's delivered, in this case it does lower the efficiency to 94%.

Jonnycoupe said:
Im not as close to chargers but Silicon IGBT in the Inverter t Silicon Carbide MOSFETTS is a big jump in efficiency. That is coming for charging retification as China AC efficiency for their drive cycles is based on energy provided from the wall and not just in the cells. The model Y i charged at home at 7kW was around 84% as i charged from empty to full. That said theres a degree of phantom/conditioning that Tesla also uses.
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I've been tracking the car since day 2 of ownership using Teslamate, it was delivered with a little under 50% SOC, just checking my first charge which was to 100% (I wanted to do a quick battery calibration run but didn't get the chance in the end to run it almost empty and back to 100%)
Teslamate:
Energy added: 43.21 kWh
Energy Delivered: 44.50 kWh
Efficiency: 97%
Average charger power: 7.2 kW
Start Soc: 44%
End Soc: 100%

Hypervolt:
Energy Used: 46.51kwh

That gives end to end, 93% efficiency..

Nothing so far in the data (including how it's tracking approximate battery health by looking at reported miles added/soc/energy used) seems to indicate a gross efficiency disparity, it's always well over 90%..

I agree 97% may be a bit optimistic, I think the 94% value is about right

We have GaN based onboard chargers showing 97% as of last year: https://www.flandersmake.be/en/insi...ctric-vehicles-energy-efficient-board-charger, and 98.5% here: https://eepower.com/new-industry-pr...eference-design-has-36-higher-power-density/#
 
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