this post was submitted on 25 Apr 2024
164 points (78.5% liked)
Technology
59569 readers
3825 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related content.
- Be excellent to each another!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, to ask if your bot can be added please contact us.
- Check for duplicates before posting, duplicates may be removed
Approved Bots
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Its kind of insane that EV manufacturers are making battery packs out of a lot of individual cells, rather than one integrated unit like this.
That's how battery chemistry works. Even this, if it is real, is a bunch of individual cells in a bank. There is no alternative; you can't have sufficient reactivity between dissimilar materials to generate the types of voltages required in a single cell. You need multiples of them in series to hit 200 volts, 400, 600, whatever is required by the vehicle's drive hardware.
Batteries, being containers for chemical reactions, are subject to the core concepts of chemistry. Namely, that increased surface area increases the speed of the reaction. You could make one enormous battery instead of multiple smaller cells, but you'd never get it to discharge fast enough to make it functionally useful.
Not a battery expert, but I think there are safety implications.
Not a China expert, but I'm pretty sure that's not a serious consideration there...
Like the other responses, the battery chemistry and design voltage are the major reasons for cell sizes, but also, smaller cells means they can be isolated if necessary.
In a Tesla battery pack for instance, each cell is connected by a single small wire that also doubles as a fuse. If there is an issue with the cell the wire will heat up and break. opening the circuit and separating that battery cell from the rest of the pack. This also means that a failed cell doesn't take out a significant portion of battery capacity. Other manufacturers do this as well, but not all, and some implement similar capability in other ways. This method functions as a sort of "passive" option since it doesn't require the BMS to make a decision to remove those bad batteries from the pack, physics just does it and the BMS adjusts to compensate when the cell no longer is connected.
Good battery management systems that handle things like charge leveling individual cells, can mean the difference between batteries degrading noticeably in a few years and the pack as a whole lasting a decade before that noticeable degradation. There are a lot of poor battery management systems on the market, EVs are no exception and if anything they make this issue more noticeable because of the increased usage.
Do you want to drive wit 3.7v? 🤣 even the smallest EV have over 3000W, so you would need a bit less than 1000A which would require giant cables
YMMD