ev efficiency

For my car (Renault 5) the official "WLTP" figures for the 90kW 40kWh and 110kW 52kWh versions are virtually identical, despite the bigger battery and possibly the more powerful motor being a bit heavier.

nib

The power rating doesn't make a big difference to range - just that more power is nippier.

What can affect things is if upgrading the trim level also includes bigger wheels, as they're less efficient than smaller wheels. That can affect range by about 10%.

Being lighter weight can give you an improvement in efficiency, but I doubt

Sometimes EVs use an LFP battery for the smaller size (as on the Renault 5), which is more robust but weighs more per kWh compared with NMC on the bigger pack (so the two versions might weigh about the same), but it seems here the Inster is using NMC on both packs

Inster 42kWh weighs 1380kg unladen Inster 49kWh weighs 1410kg unladen

So only 30kg in it - I doubt it's going to make much difference. You can compare the efficiency figures here:

Theo

About 50kg (weight range 5-8kg per kWh).

Slow day yesterday :-)

It's 30kg difference according to the official specs linked from my post. But yes, having even one passenger would increase the weight significantly more.

Theo

A full 'tank' of electrons presumably weighs the same as a 'flat' one

So it is. Relatively low battery weight it seems - about 4kg/kWh other things being equal, good stuff.

FWIW AI is sceptical - reckons some figure fiddling, athough does note the probably different chemistry of LR's battery.

Weight isn't really a thing with most EVs when comparing to their ICE equivalent. Heavier, yes, but only by 5% or so from the few I've had a look at. And that's looking like changing soon with low weight batteries in the pipeline.

Actually it is a few picograms heavier, E=mC^2 etc etc.

Low weight batteries have been here since 2000 They ain't gonna get much lighter

What is the basis of your assertion that larger wheels are less efficient? I'm not saying you're wrong (yet) but I just want to understand what you are saying.

Are you saying that larger wheels and tyres have a larger moment of inertia so that you use more energy to accelerate them, which you may not get back when you slow down again?

Or is it something to do with rolling resistance? When larger wheels are fitted to an EV, they are invariably accompanied by lower profile tyres so as the keep the rolling radius more or less the same and not interfere with the gearing. Are you saying that a lower profile tyre has a greater rolling resistance than a higher profile tyre?

It's very common on EV reviews and specs. Look up the rated mileage of different trims and the ones with larger wheels have a drop in range. (that should have been 'by up to about 10%' - the exact delta varies)

It's rolling resistance that makes the difference AIUI.

Theo

For the Inster - Long range 229 miles with 15" wheels Long range 223 miles with 17" wheels This is far below 10% (nearer 3%)

Solid state batteries - about 60% of the best currently available:

wide tyres have more contact area and absorb more energy in deformation, which is why bike tyres are so narrow

Yawn, Moire ecobollox.

Just take a course in electrochemistry

Plus the Long Range is the heavier car. I'd have thought that as far as wheels go it's mainly related to the width of the tyre, not the diameter.

'Bike tyres have to have a round cross section otherwise cornering would be somewhat interesting, this pusehes them towards being narrow. Big, powerful 'bike tyres are quite fat.

Look at your experience, What tyres do bicycles use, and why? Large diameter, narrow width, extremely low profile.

rolling resistance is down to the forces reducing deformation ...we only use tyres to stop wheels chattering on hard surfaces and give some grip

They said the same about CATL's sodium battery compared to lithium, but I've seen videos that show otherwise ...

Ultimately any stored energy that escapes in a hurry is a fire or explosion risk

Hydrocarbon fuel is good in that it is engineered to sit somewhere between peak energy to weight ratio (hydrogen) and peak safety (coal). And the fires can be put out with water because IC engines need air as well, to work.

Electric batteries contain all they need to make a lot of heat. They don't need air. And the more efficient they are the more capable of going bang they are. (Low internal resistance)

And electrochemistry defines the theoretical maximum energy density. Which is lithium.

Sodium will always be heavier,. That doesn't make it useless for large ground based batteries or car starting, but it does make it worse for car traction batteries