EV Discussion thread

1961Nick

A critical factor that appears to be missing from the article is that low mileage ICE vehicles do a lot of short local trips so it's likely that a significant proportion of the total mileage will be with a cold engine & therefore the cold start extra emissions (CSEE) will be significant. Including that element when comparing the overall ICE v. EV emissions break even point could make a considerable difference.

JKenH

1961Nick said:

A critical factor that appears to be missing from the article is that low mileage ICE vehicles do a lot of short local trips so it's likely that a significant proportion of the total mileage will be with a cold engine & therefore the cold start extra emissions (CSEE) will be significant. Including that element when comparing the overall ICE v. EV emissions break even point could make a considerable difference.

You get a similar effect with EVs used for short trips (especially in cold weather) but it can take even longer to get a battery up to ideal operating temperatures. I have seen consumption figures of below 2 mpkWh from my Leaf over the first couple of miles of a run before ending up at twice that figure. Of course with short trips in an EV in cold weather a greater proportion of energy is used on the HVAC whereas in an ICE car you just shiver until there is sufficient heat from the engine to keep you warm. Perhaps some of these losses go unnoticed if the car does not record them. I don’t know if any EVs take into account the preheating energy used before you get in the car and turn on the “ignition”. 

1961Nick

ICE vehicles also have vampire drain but you're unlikely to notice because there's no convenient way of seeing the battery SOC. Obviously using an ICE to power the alternator to replenish the battery is pretty inefficient compared charging using mains electricity.

Sentry mode can consume a huge amount of energy if it's constantly being activated by passing cars & pedestrians. I use mine selectively rather than every time I park the car. It can be activated remotely from the app if you change your mind or want to have a look at the cameras.

JKenH

1961Nick said:

ICE vehicles also have vampire drain but you're unlikely to notice because there's no convenient way of seeing the battery SOC. Obviously using an ICE to power the alternator to replenish the battery is pretty inefficient compared charging using mains electricity.

Sentry mode can consume a huge amount of energy if it's constantly being activated by passing cars & pedestrians. I use mine selectively rather than every time I park the car. It can be activated remotely from the app if you change your mind or want to have a look at the cameras.

Negligible, though, otherwise our 12v batteries would go flat overnight. 

Grumpy_chap

JKenH said:

They probably arrived with yours on this ship.

That would explain why the "ready for delivery" car I ordered on 18th was not actually available to collect on the first date given, Friday 23rd and I had to wait the extra week to collect yesterday, 30th.  Ties in with the ship in port 25th to 28th.
That actually worked out well in the end as, last weekend, I was so busy with quarter-end reports for work that I would have struggled to have fitted in collecting the car as well.

I noted today, the SC offers are gone but the base discounts remain.  Based on past profiles, those base discounts will be removed in the next week once the "wash-up" orders from June have been placed this weekend.

I am dead chuffed with my car, though, and pleased with the price / package I secured.  For once, I seem to have timed things with fortunate coincidence

Hoping to swap over the number plates to the "personalised registration" just as soon as the V5 arrives in the post - likely to be Thursday based on the time for the Certificate of Entitlement to arrive.  Planning for a trip with Mrs G-C and Mummy G-C next Saturday.  It is 100 miles each way, so I believe and feel fairly confident I can cover that without considering a charge in either direction.

JKenH said:

Doesn’t your Tesla do that already with the Octovalve?

Aaah - yes, it would appear so.  I have the heat pump package "Cold Weather Feature" in Tesla phraseology. I hadn't heard the term "Octovalve" before but that seems to be part of the heat pump package and heating the cabin as part of battery cooling seems to be part of that package.  No experience of cabin heating yesterday as the car would have been cooling the cabin for comfort purposes.

I understand the latest Nissan Leaf also has a heat pump so, presumably, does something similar for cabin heating.

JKenH

Grumpy_chap said:

JKenH said:

They probably arrived with yours on this ship.

That would explain why the "ready for delivery" car I ordered on 18th was not actually available to collect on the first date given, Friday 23rd and I had to wait the extra week to collect yesterday, 30th.  Ties in with the ship in port 25th to 28th.
That actually worked out well in the end as, last weekend, I was so busy with quarter-end reports for work that I would have struggled to have fitted in collecting the car as well.

I noted today, the SC offers are gone but the base discounts remain.  Based on past profiles, those base discounts will be removed in the next week once the "wash-up" orders from June have been placed this weekend.

I am dead chuffed with my car, though, and pleased with the price / package I secured.  For once, I seem to have timed things with fortunate coincidence

Hoping to swap over the number plates to the "personalised registration" just as soon as the V5 arrives in the post - likely to be Thursday based on the time for the Certificate of Entitlement to arrive.  Planning for a trip with Mrs G-C and Mummy G-C next Saturday.  It is 100 miles each way, so I believe and feel fairly confident I can cover that without considering a charge in either direction.

JKenH said:

Doesn’t your Tesla do that already with the Octovalve?

Aaah - yes, it would appear so.  I have the heat pump package "Cold Weather Feature" in Tesla phraseology. I hadn't heard the term "Octovalve" before but that seems to be part of the heat pump package and heating the cabin as part of battery cooling seems to be part of that package.  No experience of cabin heating yesterday as the car would have been cooling the cabin for comfort purposes.

I understand the latest Nissan Leaf also has a heat pump so, presumably, does something similar for cabin heating.

The Leaf does indeed have a heat pump but the battery has no thermal management so no heat to scavenge.

1961Nick

JKenH said:

1961Nick said:

A critical factor that appears to be missing from the article is that low mileage ICE vehicles do a lot of short local trips so it's likely that a significant proportion of the total mileage will be with a cold engine & therefore the cold start extra emissions (CSEE) will be significant. Including that element when comparing the overall ICE v. EV emissions break even point could make a considerable difference.

You get a similar effect with EVs used for short trips (especially in cold weather) but it can take even longer to get a battery up to ideal operating temperatures. I have seen consumption figures of below 2 mpkWh from my Leaf over the first couple of miles of a run before ending up at twice that figure. Of course with short trips in an EV in cold weather a greater proportion of energy is used on the HVAC whereas in an ICE car you just shiver until there is sufficient heat from the engine to keep you warm. Perhaps some of these losses go unnoticed if the car does not record them. I don’t know if any EVs take into account the preheating energy used before you get in the car and turn on the “ignition”. 

The difference is that the coldest start of the day for an EV is first thing in the morning just after charging with very low carbon overnight electricity. A battery is much better at retaining heat than an ICE so subsequent restarts won't require much battery heating... or any in summer. It takes an ICE vehicle several minute to get the cat up to operating temperature.

1961Nick

JKenH said:

1961Nick said:

ICE vehicles also have vampire drain but you're unlikely to notice because there's no convenient way of seeing the battery SOC. Obviously using an ICE to power the alternator to replenish the battery is pretty inefficient compared charging using mains electricity.

Sentry mode can consume a huge amount of energy if it's constantly being activated by passing cars & pedestrians. I use mine selectively rather than every time I park the car. It can be activated remotely from the app if you change your mind or want to have a look at the cameras.

Negligible, though, otherwise our 12v batteries would go flat overnight. 

The initial vampire drain for ICE is significant but they start to shut systems down as the voltage drops - things like remote start will cease to function after 24 hours.

Grumpy_chap

OK, so I am trying to understand my "MPG" or miles/KWh for my drive home on Friday evening.
My understanding was that anything over 4 miles/kWh is good.

I collected the car, TM3 LR, with 90% battery charge.
Official range is 374 miles, so 90% means 335 miles.
My journey was 71 miles with lights, wipers, air con, motorway speed. 
70 mph where possible, but some roadwork sections at 50 mph.
Started at sea level, ended in London, so a slight overall elevation gain
Battery charge showing on arrival 69%

When I found the energy meter, it says average 181 Wh/mi.
Unless my maths is wrong, that would mean >5.5 miles/kWh.
Is that correct " 1 divided by 0.181" to invert from Wh/mi to miles/kWh?

The same graph shows estimated range at 292 miles.  
I read that as remaining estimated range.
It could mean estimated range on that full charge ("tank").

The notes said to accelerate more smoothly - consider chill mode.

I know 71 miles is a short test, but is that correct that I calculated such a high miles/kWh.
I feel I may have made a mistake somewhere.

EDIT:  Another way to look at this is start 90% charge, finish 69% charge.  That means 21% used.  Against range of 374 miles, that would be 78 miles so my 71 miles was under-par.

silvercar

Grumpy_chap said:

OK, so I am trying to understand my "MPG" or miles/KWh for my drive home on Friday evening.
My understanding was that anything over 4 miles/kWh is good.

I collected the car, TM3 LR, with 90% battery charge.
Official range is a little under 374 miles, so 90% means 335 miles.
My journey was 71 miles with lights, wipers, air con, motorway speed. 
70 mph where possible, but some roadwork sections at 50 mph.
Started at sea level, ended in London, so a slight overall elevation gain
Battery charge showing on arrival 69%

When I found the energy meter, it says average 181 Wh/mi.
Unless my maths is wrong, that would mean >5.5 miles/kWh.
Is that correct " 1 divided by 0.181" to invert from Wh/mi to miles/kWh?

The same graph shows estimated range at 292 miles.  
I read that as remaining estimated range.
It could mean estimated range on that full charge ("tank").

The notes said to accelerate more smoothly - consider chill mode.

I know 71 miles is a short test, but is that correct that I calculated such a high miles/kWh.
I feel I may have made a mistake somewhere.

Are you sure you were looking at the trip and not the total since last reset?

I'd say that you did very well. All your calculations look correct, though I thought the official range is 360 not 374. Tapping the 69% should flip between that and estimated miles. I would expect that 69% be about 250 miles. I think it will settle down after a few drives. And people have shown (real life testing rather than manufactures theory) that air con uses far less power than heat, so in Summer that's another reason why you get more miles for your £.