The sweet spot

[Everest]

I was musing over the thread about IM5/6 consumption of around 2.8 miles/kWh and wondering if anyone has done a study to find the sweet spot in terms of battery capacity vs. range - or at least a graph plotting the relationship graphically.

In other words, are we really gaining much by increase of capacity beyond say 80kWh or is it just a law of diminishing returns? Obviously a 100kWh vehicle will be heavier, so there will be a loss of efficiency. But then that vehicle will be more expensive and hence need to be bigger and more lavishly equipped to justify the price, which in turn will make it even less efficient.

 

[LenEV2016]

I was musing over the thread about IM5/6 consumption of around 2.8 miles/kWh and wondering if anyone has done a study to find the sweet spot in terms of battery capacity vs. range - or at least a graph plotting the relationship graphically.

In other words, are we really gaining much by increase of capacity beyond say 80kWh or is it just a law of diminishing returns? Obviously a 100kWh vehicle will be heavier, so there will be a loss of efficiency. But then that vehicle will be more expensive and hence need to be bigger and more lavishly equipped to justify the price, which in turn will make it even less efficient.

I don't think you can look further than Tesla for the sweet spot of range, efficiency and power.

Tesla model 3 LR rwd 79kwh usable and 360 miles range on average.

Lucid are up there also but not in the UK yet

 

[Gomev]

I have never had a Tesla and probably never will (purely for car reasons nothing else) but I do admire their efficiency.

 

[tsedge]

It's also possible that Tesla and Lucid are pushing efficiency beyond the economic optimum. Both companies are technology-obsessed to the point of innovation before their existing technologies have matured in adoption.

The market will determine this over time. To me, we have some established norms already:

- Sub-40kWh: used for city cars and/or cheap end of the market. Perfect for a second car that doesn't need to do long journeys. Typically up to 150 miles of range (dependably).

- 40-70kWh: the sweet spot for a family car, with long journey capability and enough range (200-300 miles) for the vast majority of the population.

- 70-100kWh: big car territory, including SUVs, executive saloons/hatchbacks. Big battery partly for range (300-400 miles) but mostly for weight and performance.

Tesla's batteries are smaller than average for the equivalent car, because of their great efficiency, but this doesn't mean that's where the market will settle.

On the contrary, Tesla are likely to have taken it farther than most manufacturers will, so I'd expect the normal to settle somewhere above the average Tesla pack size.

We should remember that the best technology/efficiency almost never wins in the long term. It's the "good enough" all round offering at a low price that tends to win out.

Edit: This is also why ICE cars don't on average do 80+mpg. That would be possible technically, but it isn't where the market settled.

 

[MG Clive]

That's a very comprehensive analysis @tsedge

 

[Everest]

Great points. I suspect that , over time, your 40-70kWh range (possible 50-70kWh) will become the most common when it can be coupled with even faster charging times. Having said that, a larger battery pack will always be able to be charged (in terms of range) faster than a smaller one as each cell needs less energy put into it for similar distance.