Battery Degradation - 2014 vs 2015 Spark EV

[Planerench]

It is my understanding that the 2015 Spark EV battery was changed to a lighter LG battery and the gearing was adjusted for better highway performance. Since I have both a 2014 and 2015 and have run both on the freeway, my experience is that the 2015 gives slightly better performance on the freeway.

It's the other way around. Because the 2015/16 have less power (400ft/lb vs 327lb/ft) they put lower gearing in. This improves acceleration, likely making up for the power loss. But, it means that the motor is spinning faster at any given vehicle speed.

Put another way, the 2014 had so much power that it could operate in "2nd gear" all the time. The 2015/16 operates in "1st gear" all the time.

So 2015/16 should be worse on the highway since the motor should be less efficient at higher RPM.

I found this which substantiates what you said:

"Of importance here is that GM had tested two different final drive ratios in the Spark EV. One, a 3.17 ratio, was eventually adopted for use in the production 2014 Spark EV. The other, a 3.87 ratio, will come standard on the 2015 Chevy Spark EV.

But that 3.87 ratio for the final drive is a significant alteration. The switch to 3.87 should increase city range for the Spark EV. However, in announcing that LG Chem will be responsible for the 2015 Spark EV battery (no longer is A123 involved), General Motors suggested that no MPGe or range ratings will change for 2015"

Here is the link to the full article: https://insideevs.com/2015-chevy-spark-ev-highlighting-changes/

Everything I have learned of mechanics and electricity tell me that the 2014 should be better at freeway cruising and the 2015/2016 should be better in town, but it is hard to argue with a guy that owns both!

 

[Planerench]

I assume by “performance” we are talking about kw per mile.

 

[NORTON]

I assume by “performance” we are talking about kw per mile.

Exactly!
Or 'Instantaneous kW usage' to roll both cars, side by side, down the road at, ? pick a speed.
Sure, we only have a display resolution of 1 kW of 'Power'.
What if you had an accurate OBD-II way of getting some decimal points in that 'Instantaneous Power' number?

Will a '14 vs a '15 draw any more or less power to overcome The Drag of rolling down the road?
Sure the actual motors are spinning at different speeds, but does that matter in an EV?

 

[Planerench]

I wonder what would happen if you simply switched planetary gear sets?

 

[NORTON]

I wonder what would happen if you simply switched planetary gear sets?

My guess would be: Absolutely nothing.

This spinning permanent magnet rotor is effected by the power flow in the stator.
Free Spinning fast or slow there may not be much difference in frictional drag.

This is not like an ICE where it's always pumping pistons and air and sucks a lot of power to do that in relation to RPM.

 

[Planerench]

I wonder what would happen if you simply switched planetary gear sets?

My guess would be: Absolutely nothing.

This spinning permanent magnet rotor is effected by the power flow in the stator.
Free Spinning fast or slow there may not be much difference in frictional drag.

This is not like an ICE where it's always pumping pistons and air and sucks a lot of power to do that in relation to RPM.

If the 2014 electrical installation didn’t know it had lower gearing the result would be increased torque supplied to the wheels. As far as I can tell.

 

[Planerench]

Interesting note: my 2014 was delivered to me 10/4/2017 with 8801 miles on it. Manufacturing date was 3rd quarter of 2013. The rough battery capacity was 16.7-16.8kwh for the first couple months. I now have 13400k miles and the battery capacity is slowly getting better. I routinely see 17.2. I wonder if the computer is recalculating long term numbers based on regular use vs test driving or if exercising is actually relaxing the pack? The only time I see under 17kwh now is after long, hard runs such as hill climbing to the ski lodge.