I-Pace Benchmarking - Jaguar I-Pace EV400 Forum
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post #1 of 8 (permalink) Old 05-10-2019, 08:34 AM Thread Starter
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I-Pace Benchmarking

Picked this up from the UK board, interesting.

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post #2 of 8 (permalink) Old 05-10-2019, 11:58 AM
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94.2 actual battery size probably explains the 100% charging as default. It never exceeds a 90% charge.

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post #3 of 8 (permalink) Old 05-10-2019, 01:45 PM
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I agree with the concept, but I wouldn't trust that kWh number. Each cell has a nominal voltage of 3.6V at 50% of capacity. Times 108 = 388.8V, which is what they cite as the nominal voltage of the pack. Fair enough. But multiply that with the cited 238Ah capacity and you get 92.5kWh. So their own numbers are inconsistent.

I thought I saw in the JLR documentation somewhere that the capacity of each cell is 58Ah. Times 4 = 232Ah, not 238. 232Ah x 388.8V = 90.2kWh. But anyway:

The reason kWh don't always match up is that you can't directly measure kWh in a battery because at the SoC extremes there is an interaction between voltage and charge that is not fully understood. At very low SoC, voltage is lower; at high SoC, voltage is higher for these types of batteries, so the battery management system probably integrates a bunch of parameters to decide when to start and stop charging / discharging. Is there room for "more"? Surely, but that comes at the risk of greater cumulative damage over lots of charge/discharge cycles.
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post #4 of 8 (permalink) Old 05-10-2019, 02:59 PM
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When charged, these cells are ~4.2 vdc, sometimes higher. 108 kWh? when taken to peak voltage?

I have some LG Chem cells that have been sitting since 2013 from a junkyard Chevy Volt. They are 3.89. No idea on SOC. Chevy Volts only charge to about 68% SOC when brand new, full charge. They are 16.0 kWh with only 10.8 kWh usable.

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post #5 of 8 (permalink) Old 05-10-2019, 03:23 PM
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Quote:
Originally Posted by McRat View Post
When charged, these cells are ~4.2 vdc, sometimes higher. 108 kWh? when taken to peak voltage?
There you go, 108kWh!! A number to support our wishful thinking

Quote:
Originally Posted by McRat View Post
I have some LG Chem cells that have been sitting since 2013 from a junkyard Chevy Volt. They are 3.89. No idea on SOC. Chevy Volts only charge to about 68% SOC when brand new, full charge. They are 16.0 kWh with only 10.8 kWh usable.
Wow, they really had a huge buffer ... perhaps that chemistry was more susceptible to damage at high SoC?

For people's enlightenment I'm attaching a figure from a IEEE conference publication (Hannan et al 2018, State-of-the-Art and Energy Management System of Lithium-Ion Batteries in Electric Vehicle Applications: Issues and Recommendations) that explains the key concepts in this discussion.
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post #6 of 8 (permalink) Old 05-10-2019, 04:02 PM
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Wow, they (the Volt) really had a huge buffer ... perhaps that chemistry was more susceptible to damage at high SoC?
The Volt is unlike other cars.

The buffer size does some magic tricks no other car did at the time:
1) Allows 3.75C regen (60kW) when the battery is at 100% SOC, more regen than some large EVs have at 50% SOC.
2) Allows 7C discharge without affecting battery life
3) Allows the "84hp" gasoline engine to produce 149hp on demand at 0% SOC by running in series mode.
4) Allows extended downhill regen with a "full" battery.
5) Extends battery life to exceed virtually all plug in vehicles. Nearly 1/2 million miles on one car.

From your picture, the Volt never operates in the gray areas, and produces full rated power at 1% SOC. Below 0%, it reduces it's discharge rate since the gasoline generator is running.

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Last edited by McRat; 05-10-2019 at 04:07 PM.
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post #7 of 8 (permalink) Old 05-10-2019, 04:34 PM
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The Volt is a nice piece of technology, probably the best hybrid ever, but it sold like crap because it wasn't really what people wanted. Those who have drunk the EV koolaid know how nice it is to be ICE free on a vehicle, and those who want range and efficiency every day are better off with a Prius. In the end, there just wasn't that much market. The only reason there's a plugin market in Europe is because of all the EV only laws in inner cities.
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post #8 of 8 (permalink) Old 05-10-2019, 05:03 PM
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Quote:
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The Volt is a nice piece of technology, probably the best hybrid ever, but it sold like crap because it wasn't really what people wanted. Those who have drunk the EV koolaid know how nice it is to be ICE free on a vehicle, and those who want range and efficiency every day are better off with a Prius. In the end, there just wasn't that much market. The only reason there's a plugin market in Europe is because of all the EV only laws in inner cities.
I was focusing on the battery technology they used. Most Euro PHEVs are extremely short range and cannot complete all the EPA test cycles without the motor starting. But this is what the law favored. Example 2019 MB GLC350e, 0-9 miles All Electric Range, 25 mpg.

Even the Plug In Prius never had full power or significant EV range (AER 2012 = 0-6 miles, 2019 = 0-25 miles). The "0 to xx" means it could not pass all the EPA test cycles on electricity, it lacked the power necessary.

The Prius Prime had an AER range bump because California was going to stop HOV access for cars with under 22 miles of AER. You floor it, and it uses gas. Or you get run over. More than 12 seconds to reach 60 mph on electricity.

If you wanted 40 mpg full sized trucks and real SUV (seats 6 full sized adults or more, tows a car trailer), the only solution with today's technology and EV infrastructure would be something like the Voltec technology. Battery large enough for >75% of daily use, gas engine for interstate travel or heavy towing.

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