diamond.g
Active Member
Wouldn't supercharging destroy the battery life without active cooling? To be honest I am unsure how good cooling just the bottom of the pack would be for high rate DC charging.
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Overall, everything that reduces complexity is in general a good thing. I'm torn whether or not 25% degradation in 8 years is good or bad. Mind you, average age for cars in this part of the globe is around 12 years or so.
Closest I've come to the buzz saw (
) I've come is via youtube videos, so no denying the fact that you have more information than me regarding how it behaves 
As Elon has discussed many times, Tesla is intent on removing the barriers to EV adoption. Two of those are:
- The trepidation folks have over battery longevity
- The barriers to long distance travel
Longevity and associated capacity degradation are directly tied to the temperature envelope the battery operates in. Liquid cooling for thermal management helps in this arena.
Long distance travel is addressed by Superchargers. These are likely the greatest thermal loads on the battery, as li-ion cells generate more heat when charging than discharging, and Superchargers are the highest charge rates the pack will experience. This is why you'll hear the thermal management system working overtime when supercharging in any sort of warmer weather.
Barring some radical new battery chemistry, I don't see Tesla risking the reputation of the technology by compromising on thermal management.
What's more, we know they are considering a larger cell format. For a cylindrical cell, the larger it is, the less the surface area to volume ratio. This impacts how effective cooling can be, particularly air cooling.
Assuming the new cells are 22700 format, as compared to today's 18650's, that represents 61% more volume per cell, but only 32% more surface area. If anything that implies a greater likelihood that air cooling would be less effective, and that they'd retain some liquid cooling system.
- The trepidation folks have over battery longevity
- The barriers to long distance travel
Longevity and associated capacity degradation are directly tied to the temperature envelope the battery operates in. Liquid cooling for thermal management helps in this arena.
Long distance travel is addressed by Superchargers. These are likely the greatest thermal loads on the battery, as li-ion cells generate more heat when charging than discharging, and Superchargers are the highest charge rates the pack will experience. This is why you'll hear the thermal management system working overtime when supercharging in any sort of warmer weather.
Barring some radical new battery chemistry, I don't see Tesla risking the reputation of the technology by compromising on thermal management.
What's more, we know they are considering a larger cell format. For a cylindrical cell, the larger it is, the less the surface area to volume ratio. This impacts how effective cooling can be, particularly air cooling.
Assuming the new cells are 22700 format, as compared to today's 18650's, that represents 61% more volume per cell, but only 32% more surface area. If anything that implies a greater likelihood that air cooling would be less effective, and that they'd retain some liquid cooling system.
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While less degradation is certainly desireable, if the options were, for the same price:
A) simpler systems, 60 kWh (+10%) battery that degrades to 45 kWh (-25%) in 8 yrs
B) more complex systems, 55 kWh battery that degrades to 47 kWh (-15%) in 8 yrs
I'd definitely pick option A.
Dan Detweiler
Active Member
Been doing it for four years in my Volt. To me that is the reassuring sound of long term battery life. I will gladly put up with it...in my Volt and in my Model 3.
Dan
Trail Runner
Member
Reeler
Decade of Pure EV Driving
I am on my 4th Leaf. Two 2011, one 2013, and a 2016. I use the last two currently. I think there have been 2-3 battery iterations since the 2011 version for Nissan. I think the most recent ones are better, but probably won't own them long enough to find out.
Reeler
Decade of Pure EV Driving
Looks like LG/Bolt and BMW have a far simpler and effective system than the Model S/X. Let's hope the Model 3 is not saddled with the Gen1 kludge in current Tesla models.
Didn't have time to go through the article in detail, how well does that system work with battery heating in cold temperatures?
I'd assume that Model S's and Xs get gen2 system before the 3 is out, and as a consequence the 3 will also have gen2 system.
Reeler
Decade of Pure EV Driving
JeffK
Well-Known Member
I don't see the other manufactures using such high current for charging and discharging... Therefore whatever they are doing is irrelevant and/or inadequate for a performance application. In addition, most probably need better cooling solutions because they have a lower surface area to volume ratio for the cells.
Yes, Tesla is not yet a tech leader in battery thermal management which is surprising given their business. In addition to the LG/Bolt/BMW system, there are other prospective systems such as GCoreLab's out of Singapore which may be even lower cost.
diamond.g
Active Member
True, but it needs to be noted when comparing these things is that one is comparing something that exists today (and can be upgraded) to something that isn't even in existence yet.
diamond.g
Active Member
And with that e-tron they could be using complicated cooling system for the BMS, we don't know yet.
You are speaking present tense with LG/Bolt and BMW. While there's evidence that BMW is using it in the i3, it's likely a bit early to determine how effective it is. The article only hypothesizes that the Bolt will have it, so it's definitely too early there.
As for kludge? Please.
The dual-loop design also allows waste heat from the drive unit or the pack heaters to use the same plumbing to also warm the batteries in cold weather, avoiding separate systems to have to be integrated in to the pack. Unless, of course, the BMW an LG designs intend to forego cold temperature thermal management.
The roadster pack has shown exceptional performance from an energy retention standpoint. The Model S appears to do at least as well, if not better. The other players really don't have much of a track record yet, so calling Tesla's proven design a kludge seems a bit much, no?
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