[Misc] Electric Cars

[Bozza]

Still in my first week of ownership but doing the Goring to Burgess Hill trip a couple of times, it seems like my mi/kwh figure is better on the way up which is A24 and cross country through Partridge Green and Twineham than the journey back which is A23/A27.

Do people find it generally the case that you get better 'economy' on slower routes or is it the impact of the regenerative braking that comes with roundabouts and country roads?

Yep. Faster speed = more air resistance = lower range.

A broad rule of thumb I read somewhere-or-other is you lose c10% of range for every 5mph above 40mph you do.

 

[Audax]

On return journeys when aiming to get home without a 'splash and dash' I find having Google maps or whatever satnav you use on with distance remaining and keep monitoring the difference between that and the GOM. If the difference is closing rapidly then modify your speed especially on motorways.

I've done this a few times. Really good advice IMO.

Largely it is just speeds. You get a lot more miles for your charge at 55mph than at 70mph.

Speeds, and also road types. Know what roads you'll be on and when. Motorways where traffic is flowing will eat range. A roads where you've got corners, junctions, etc and a little more stop-start and range will improve. More uphill than downhill and range will suffer (and vice versa).

Also, with EVs ... back off when following traffic. The less you have to brake-accelerate the better. Sit back far enough from the car in front that you can lift-and-coast to manage the gap rather than feeling the need to use the brakes and your GOM will thank you.

 

[Greg Bobkin]

Still in my first week of ownership but doing the Goring to Burgess Hill trip a couple of times, it seems like my mi/kwh figure is better on the way up which is A24 and cross country through Partridge Green and Twineham than the journey back which is A23/A27.

Do people find it generally the case that you get better 'economy' on slower routes or is it the impact of the regenerative braking that comes with roundabouts and country roads?

Yes, deffo speed, but also I would think the first bit of the journey would be hampered because the battery is cold, so needs to work harder. Hence why a lot of cars now have pre-conditioning. It's funny because a lot of people will say they want to get home as fast as possible, even if they have to charge – and yet if they dropped their speed a bit, they would have the miles to get home WITHOUT having to charge and it would STILL be quicker than stopping to charge.

I've had it a few times (just last week, in fact) where I thought I would be stopping at Pease Pottage, but because the M25 was busy, the average speed along it was such that I made up enough miles to NOT have to stop

This comes back to my wider point that I've probably said here (and certainly have committed to print), that many EV drivers drive more slowly (to eek out the miles) and are therefore more relaxed and – arguably – safer. I certainly am.

 

[alanfp]

Yup.

The car will travel at a steady speed (e.g. motorway) without using any energy (Newton's 1st law)... APART FROM having to overcome any resistance like friction and air resistance. Air resistance is proportional to the SQUARE of the speed, so the resistive force at 70 mph is virtually DOUBLE that at 50 mph.

Energy is used to accelerate the car (Newton's 2nd law of motion aka F=ma) but a significant amount will be recovered by recharging the battery when slowing down (if you can avoid using the brakes as much as possible).

And energy is required to go uphill, as that increases the car's potential energy (m x g x h) but on average this largely gets recovered by recharging the battery when going downhill to the same elevation that you started at.

 

[hans kraay fan club]

Yup.

The car will travel at a steady speed (e.g. motorway) without using any energy (Newton's 1st law)... APART FROM having to overcome any resistance like friction and air resistance. Air resistance is proportional to the SQUARE of the speed, so the resistive force at 70 mph is virtually DOUBLE that at 50 mph.

Energy is used to accelerate the car (Newton's 2nd law of motion aka F=ma) but a significant amount will be recovered by recharging the battery when slowing down (if you can avoid using the brakes as much as possible).

And energy is required to go uphill, as that increases the car's potential energy (m x g x h) but on average this largely gets recovered by recharging the battery when going downhill to the same elevation that you started at.

So you’re telling me that if I want to drive at 70 on the motorway, it’s best to do it right up close behind a big truck?

 

[Greg Bobkin]

So you’re telling me that if I want to drive at 70 on the motorway, it’s best to do it right up close behind a big truck?

'Best' is subjective (clearly it's not the safest method of driving!), but it can work if you're looking to maximise efficiency, yes.

 

[Bozza]

So you’re telling me that if I want to drive at 70 on the motorway, it’s best to do it right up close behind a big truck?

Probably not.

Because BIG trucks are limited to 60mph.