Source: https://investor.gm.com/events/event-details/general-motors-ev-day General Motors EV Day Mar 4, 2020 from 12:30 PM to 2:30 PM EST General Motors Company will host a webcast for the investment community on Wednesday, March 4th, 2020 at 12:30 PM EST. Please join us to learn more about GM’s electrification strategy. The event will include remarks from management and subject matter experts, followed by a question and answer session. A webcast link and dial-in for the event will be available under the “Events” section of GM’s investor website. A replay of the webcast will be available following the presentation. Bob Wilson
Shortly after their battery expert bragged about their huge, pouch cell, I had something better to do. The reason why: large area pouch cells have a thermal management problem - it tends to have hot and cold spots on the edges and when any part of the large area fails, the whole cell fails. Large formats have isothermal challenges. mass of smaller, isolatable cells handles failures softly - fewer large format cells means if one fails, the pack is screwed. In contrast, mobs of smaller cells handle problems by isolating the failed cell and continuing the trip. I'll review the playback later but when I saw the 'hump' in one of their battery examples, I knew they were as clueless as their EV1 decisions. Bob Wilson
In order to look at battery, you need look at the minimum at : amount of charge it will hold (a proxy for range), charging time, deterioration over a period of time (longevity), size and dimensions etc. (this is being simplistic) GM seems to have been more interested in quicker charging times, a form factor that will allow it to be stackable (being rectangular you have a higher packing density) and hence better range. For that they have sacrificed longevity. The cylindrical form does have some advantages. There is some talk about thermal management, but they want to compete on range and charging time. Oh Well!!!! But BTW GM's share price jumped 2.5% on the news of their big investment in EVs, to $31.21, as of 3 p.m. in New York.
I appreciate their effort but battery thermal management is not trivial. I need to review the playback. The reason is our Tesla swing the battery temperature about 20C between 50C optimum charge and 30C optimum operational temperatures. This transition is where a thermal gradient can lead to a bad result. Bob Wilson
Just finished my review: Nickel Cobalt Managenese Aluminum (NCMA) vs Tesla Nickel Cobalt Aluminum (NCA) - we'll need samples for testing. Tesla 2170 cells are readily available wide coating of electrodes - they claim economies of scale, once the battery plant comes online smallest number of the largest cells - which means one cell failure leads to a bricked car. Those of us with Prius experience know how a single cell failure leads to problems. 100 Ah cell - @3.7 V, 3,700 Wh per cell 20 layers per cell flat bottom (long edge) connected to cold-plate - this suggests there will be a significant thermal gradient which means a mechanical strain between the cold plate and far edge. In our Model 3, the cells are warmed to ~50 C for charging but cooled to ~30 C for operation. The thermal gradient is from the rim to the core which significantly reduces the thermal, mechanical strain. zeolite - an ion holding material Bolt EV battery comparison - 25% weight reduction, 50% fewer connections vertical integration - a GOOD THING, GM is not outsourcing the critical technology What was omitted: Corvette EV - a Tesla roadster competitor Bob Wilson
I understand this Auto Line After Hours will be a hoot: Reporter Roundtable Christie Schweinsberg, Wards Intelligence; Joe White, Reuters; Gary Vasilash, AD&P; John McElroy, Autoline.tv LIVE March 5@ 3:00PM EST Bob Wilson
So here are a couple of images: Here are there different pack configurations showing GM's approach. Notice the inconsistent "modules" from the three pack configurations. But this is what 'raise my eyebrows': They have a center 'tunnel' of battery cells, not their 'module', to replicate the legacy drive shafts that screwed up cars since forever. DUMB! Bob Wilson
That is hilarious, a flat floor would have a better approach like these 2 American icons: https://www.hagerty.com/articles-videos/articles/2019/09/06/design-evolution-olds-toronado-from-cord-810
Did not want to start a new thread as it is related to this topic https://insideevs.com/features/403530/gm-put-tesla-out-business/ Op-Ed: GM Could Put Tesla Out Of Business Or Not (or not is my addition) This op-ed in fact criticizes the GM strategy and make some good points. Some other article claimed GM would be put Tesla out of business. This writer says no. And after Bob's (@bwilson4web ) great analysis, I cannot but agree. Dear GM Management: Congratulations on your EV Day event. It's great to see you make intimations of serious intent to move toward electro-propulsion. However, I do have some thoughts about what was presented. The thing that I find most crazy about your proposed EV strategy is that you are relegating yourselves to playing in Tesla's sandbox. You’re playing right into their hands. You're running the large battery pack, hope to get the cost down, race. You are hoping to speedily navigate the curve. Essentially you are trying to do the same thing Tesla is doing, and hoping to be able to do it as well or better than the market leader. A leader who has an eight-year head start. Does that sound smart? Here's the memo for you. You're not going to be able to beat them at their game. April will be a revelatory month. If Elon's recent comments on the "Third Row Tesla Podcast" are any shadow of what's to come, Tesla is going to rule the day its way................. ......Or, just keep playing Tesla's game Tesla's way for another 12 years and see how that works out for you. If you’re still around.
