Cell Suppliers & ESS Thermal Management for Proterra, BYD Buses

[MikeMcD]

Hi all,

I thought I'd kill two birds with one stone in this thread.

I am pretty active in keeping up with regular EVs and am generally interested in the technology. I have an extensive background in Li ion batteries so that's useful here.

Anyway, I am now trying to get up to speed on the state of electric buses. I have a lot of familiarity with New Flyer but would like to know how other OEMs like Proterra and BYD compare in terms of their technology. I have scoured the internet but unearthing any specific information, especially as a non-customer, has been difficult. I was wondering if some of the fanboys on this site could help me out.

Specifically, I am curious about the cell suppliers and battery thermal management for these two OEMs. BYD I know is a battery manufacturer who makes vehicles based on their technology. As I understand, they use LFP chemistry only, which is weird considering the energy density needed to achieve range for this application. Given the more stringent asks from public transport regulators for range, I would think they would want to start manufacturing NMCs (possibly the upcoming 811 chemistry) soon? Anyone know if this is a thing, or will they stick with LFP?

For Proterra, I believe their supplier is LG Chem (from which they build packs). Anyone know their technology pathway to improve energy density in the coming years?

Second part is thermal management. Proterra's site indicates they have active thermal management. I have not been able to decipher is BYD takes this into consideration, though. Can anyone confirm their method (if at all)? It wouldn't surprise me if they don't have their dedicated BTMS, especially considering LFPs give off significantly less waste heat compared to NMC.

I understand this is a mouthful but this could be a good conversation, especially since there appears to be a lack of topics re: Ebus tech. Thanks very much in advance for any input!!

 

[Domenick]

I'm not familiar with the temperature control BYD uses in its buses. I've got to imagine they doing something, though. Overall, I found their approach to be lacking. They've made a number of sales because they probably have an extremely competitive price, especially compared with Proterra. However, their vehicles, in some situations at least, haven't been living up to their claims.

Some of this I believe has to do with their battery choice. LFP isn't especially energy dense, and so to get the range to compete, they end up being extremely heavy. I recall they one article mentioning they were having trouble climbing hills on some routes.

Albuquerque just canceled its deal with them as well, citing safety and structural concerns. Here's another piece from earlier this year talking about lots of mechanical problems.

Sorry if I couldn't answer your actual question, but maybe this will help.

 

[Pushmi-Pullyu]

Certainly an interesting topic, but I'm afraid I can't answer any of your questions.

Until recently I thought BYD had a good reputation for building and selling BEV buses, but a couple of recent articles have made me question that. I see Domenick already linked to two articles on the subject. Here are a couple more:

From InsideEVs (News): "Albuquerque Plans To Reject And Return BYD Electric Buses"

From the L.A. Times: "Stalls, stops and breakdowns: Problems plague push for electric buses"

* * * * *

I have no doubt that LG Chem will continue to improve the energy density and lower the cost of its EV cells, but they certainly are not going to tell anybody exactly what improvements are in current development. Those details are held closely as trade secrets.

​

 

[Pushmi-Pullyu]

Second part is thermal management. Proterra's site indicates they have active thermal management. I have not been able to decipher is BYD takes this into consideration, though. Can anyone confirm their method (if at all)?

A quote from a 2018 BYD press release:

All BYD electric buses will be equipped with the latest advanced generation BYD Iron-Phosphate batteries including thermal management system
​

But that doesn't help much, since it doesn't say what type of BTMS is used. We will hope it's liquid cooling, but it could be forced air, or possibly even something passive like merely installing radiator fins around the pack.

​

 

[MikeMcD]

Excellent responses, guys. Thanks very much!

I knew coming into this that my ask was a lot. It seems like I would have to be a legit customer in negotiations with these players to get a sniff of their tech details.

 

[Domenick]

Excellent responses, guys. Thanks very much!

I knew coming into this that my ask was a lot. It seems like I would have to be a legit customer in negotiations with these players to get a sniff of their tech details.

Buses are a very important part of electrification, so it's great to have discussion about them

As a side note, this post about Chile getting 100 buses from China's Yutong has been crazy popular this week, mainly people clicking from outside the US.