Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Toyota is recycling old EV batteries to help power Mazda's production line

thedrive.com

Post reply on HN
Print view View original

51–60 of 142 posts

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#51

Post by spockz »

londons_explore wrote: post #48
lillecarl wrote: post #43

Earlier quoted context omitted.

How do you achieve this with cells in series? Do you kill an entire row and put it on "maintenance voltage"? I know how balance charging RC batteries work but they're smaller scale and "single row". Also in RC car world it's generally preferred to have one cell per voltage step, I've had way more dual-cell(per series) packs fail than single ones. Though my experience is only 6s/~22v but it's "the same shit on a bigge…

No EV that I'm aware of has the ability to bypass a single cell in a series string. I have often wondered if it would be worth designing an EV battery that can permanently short out a bad cell in a string, perhaps by deliberately disabling balancing, letting the bad cells voltage fall to zero, and then perhaps having a single use 'bypass' that latches on. It wouldn't be a seamless user experience, because if you disc…

I guess you can put a relais/switch in for each cell in a series but then you need to account for voltage differences when taking them out. Either by over provisioning within the series and rotating in different cells. Or by have other strings take up the slack.

Either way you need some form of overbooking / compensating capacity.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#52

Post by hinkley »

zhyder wrote: post #4

Neat idea to mix batteries of different age and chemistries. I've wondered why EVs couldn't do that too with some power electronics and SW. If an EV battery could have multiple such modules, it'd: 1) Make it easier to carry a cheaper lighter less-natural-resources-consuming battery most of the time. Go to some "gas station" to rent and add more modules when taking a road trip 2) Make it cheaper to replace the 1 modul…

I believe we have a new generation of supercapacitors in R&D stage. There were some experiments done in the last year that showed that some assumptions about what makes supercaps work so well turned out to be wrong. I can’t recall the details but it turns out the foamy structure of charcoal is not the optimal structure. So that should result in higher energy density per unit volume.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#53

Post by kenhwang »

omega3 wrote: post #39
kenhwang wrote: post #23

Earlier quoted context omitted.

Toyota owns a de facto controlling stake in Subaru (~20%). Due to typical Japanese corporation by-laws, it only takes 33% share ownership for uncontested control of a corporation, and >50% of 33% means they'll never lose a vote for simple majority matters, which is basically everything except selling or dissolving the company. The 20% threshold is for a guaranteed seat on the board, which lets them put issues up for…

> Due to typical Japanese corporation by-laws, it only takes 33% share ownership for uncontested control of a corporation It doesn’t make any sense.

Think of it like how Zuckerberg only owns 13% of Facebook but has >60% of the voting power.

Japanese law allows corporations to only require 1/3 of voting shares present for quorum, and then a majority of those present to pass resolutions. It also allows cross-shareholders (like Toyota) to have special privileges over regular class shareholders (typically right of first refusal over any resolution).

In practice, nothing much will pass without the largest shareholder's approval.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#54

Post by bityard »

slt2021 wrote: post #37
pornel wrote: post #28

Those who TL;DRd - it's for the factory, not the cars! Old EV batteries are great for energy storage. A worse weight-to-capacity ratio doesn't matter for batteries sitting on the ground. A battery that holds only 70% of its original capacity is considered worn-out for EVs (and even replaced under warranty), but grid storage isn't driving anywhere, so any capacity left is still useful.

this is like picking up unfinished cigarette butts and making few finals puffs before burning your mouth. worn-out batteries can swell and fail spectacularly, with fireworks

I think you may be confusing worn-out batteries with damaged batteries, these two subclasses do not have the same properties

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#55

Post by hinkley »

stetrain wrote: post #22
zhyder wrote: post #4

Neat idea to mix batteries of different age and chemistries. I've wondered why EVs couldn't do that too with some power electronics and SW. If an EV battery could have multiple such modules, it'd: 1) Make it easier to carry a cheaper lighter less-natural-resources-consuming battery most of the time. Go to some "gas station" to rent and add more modules when taking a road trip 2) Make it cheaper to replace the 1 modul…

GM claims that this is exactly how their Ultium battery pack architecture works. It is made up of multiple modules each with their own BMS, and supposedly one module can be replaced without having to be a match in chemistry and degradation to the other modules. I'm unsure if that will actually work so well in practice, where you still need to charge all the cells simultaneously when doing DC fast charging etc. Also a…

You shouldn’t need to charge them all at the same rate. Put in some cells that charge slower, fast charge the rest and continue charging the slower cells until unplugged. Consider for instance fast charging the array to 70% instead of 80%, where 1/3 of the cells are charged to 50% and the rest to 80%.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#56

Post by bityard »

lupusreal wrote: post #25
bluGill wrote: post #2

had to check: toyota owns 5% of mazda which makes them the largest shareholder.

TIL Mazda isn't a wholly owned subsidiary of Toyota. I thought it was, now I wonder where I got that from.

Related: Ford once had a 33.4% stake in Mazda and there was a bunch of cross-pollination between the two companies at that time. My 2002 Mazda Protege was loaded with various parts bearing the FoMoCo logo. And Mazda engines/chassis powered a bunch of Ford cars world-wide.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#57

Post by hinkley »

smileysteve wrote: post #14
zhyder wrote: post #4

Neat idea to mix batteries of different age and chemistries. I've wondered why EVs couldn't do that too with some power electronics and SW. If an EV battery could have multiple such modules, it'd: 1) Make it easier to carry a cheaper lighter less-natural-resources-consuming battery most of the time. Go to some "gas station" to rent and add more modules when taking a road trip 2) Make it cheaper to replace the 1 modul…

Re: 1, ignoring the complexities, is really interesting but depending on the effort to change our battery banks quickly makes renting a car more feasible. And this highlights American traffic and sparseness. - plug-in hybrids have 10-13 mile range which is great for running a few errands (this is only slightly more feasible than in a golf cart or ebikes) - also great for last mile connectivity for mass transit n user…

I’ve done the math a couple of times and IIRC if we can get the charge density per kilo to about twice what lithium ion can do, you hit a point where a deposit battery that’s around 20 kilos has enough range extension to start being worth doing. That’s the weight of a large bag of kitty litter or a commercial bag or rice. Put a good ergo handle on it and most people should be able to lift a few of them consecutively.

But until one unit is worth about 8 miles of extended range, there would be no point. 3@25 or 30 miles might make it worth the trouble for a road trip, or camping.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#58

Post by reactordev »

pornel wrote: post #28

Those who TL;DRd - it's for the factory, not the cars! Old EV batteries are great for energy storage. A worse weight-to-capacity ratio doesn't matter for batteries sitting on the ground. A battery that holds only 70% of its original capacity is considered worn-out for EVs (and even replaced under warranty), but grid storage isn't driving anywhere, so any capacity left is still useful.

More often than not these bad cells can be removed, manufactured a new, and reinstalled. Not 100% but almost good as new.

Making your own cells is fun.

For Toyota, this is trivial and the energy storage these “left over” batteries provide, given a tinkering, is sufficient.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#59

Post by hinkley »

redwall_hp wrote: post #16
bluGill wrote: post #2

had to check: toyota owns 5% of mazda which makes them the largest shareholder.

Toyota also owns Daihatsu, which is a lesser known name in the US, but is a major maker of kei cars, which are huge in Japan and other parts of Asia. They also own Denso, which is the second largest auto parts company. And they partner with Subaru on some things, such as the Subaru BRZ and Toyota GR86, which are basically the same car with different badging.

They also owned a chunk of Mitsubishi Aeroplane and IIRC invested in Mitsubishi’s 787 manufacturing division.

Re: Toyota is recycling old EV batteries to help power Mazda's production line

#60

Post by Dylan16807 »

reactordev wrote: post #58
pornel wrote: post #28

Those who TL;DRd - it's for the factory, not the cars! Old EV batteries are great for energy storage. A worse weight-to-capacity ratio doesn't matter for batteries sitting on the ground. A battery that holds only 70% of its original capacity is considered worn-out for EVs (and even replaced under warranty), but grid storage isn't driving anywhere, so any capacity left is still useful.

More often than not these bad cells can be removed, manufactured a new, and reinstalled. Not 100% but almost good as new. Making your own cells is fun. For Toyota, this is trivial and the energy storage these “left over” batteries provide, given a tinkering, is sufficient.

Your own cells? Like you put together a lasagna of metal sheets and chemical goops and roll it up?
Post reply on HN