Tesla made $1.6 billion in Q3, is switching to LFP batteries globally • Hacker News Board

Re: Tesla made $1.6 billion in Q3, is switching to LFP batteries globally

#61

Post by andruby » Fri, Oct 22, 2021, 6:07 AM UTC

tzs wrote: post #56

andruby wrote: post #47

Earlier quoted context omitted.

You can't discharge lead-acid as deeply as LFP without destroying longevity. So that 150Ah, probably only has 75Ah of useable capacity. The LFP battery will also last for ~5000 cycles, after which it'll still have ~80% capacity, and thus is still valuable. Lead acid only has a life of 500~1200 cycles. In other words: you'll have replaced the lead acid battery 4~10 times before you need to replace the LFP. IIRC, lead…

> The LFP battery will also last for ~5000 cycles, after which it'll still have ~80% capacity, and thus is still valuable. Lead acid only has a life of 500~1200 cycles. In other words: you'll have replaced the lead acid battery 4~10 times before you need to replace the LFP. What happens if you keep using the LFP battery after that? Does the capacity continue to fall to zero, or is there some point it levels off and y…

The curve seems to be pretty lineair. So I think you can do another 5k cycles and have 60% left, once more for 40% etc. A quick search didn’t reveal a full curve chart to zero though. I know that a lot of cheaper LFP cells on aliexpress are used “grade B” cells, eg cells that had an original capacity of 120Ah that are resold as 90Ah cells after their first 5k cycles.

There is a chart for 3k cycles here: https://www.ctechigroup.com/deep-cycle-life-lifepo4-cell-3-2...

Re: Tesla made $1.6 billion in Q3, is switching to LFP batteries globally

#62

Post by MrDunham » Sat, Oct 23, 2021, 2:52 PM UTC

jjav wrote: post #55

MrDunham wrote: post #11

Earlier quoted context omitted.

Completely agree. I had a thermodynamics teacher in college say “in the history of transportation we’ve never switched to something powered by lower energy density [than the previous mode of transportation]" in other words “energy density wins the day".* That was running through my head when I read they were switching to technology with lower energy density but, to your point and to the article's point, it’s really a…

> But the secondary selling point was never having to go to a gas station again when I am just barely going to make the meeting and forgot to fill my gas tank the night before. Curious example since that's one of the drawbacks of an EV. If you forgot to fill the gas tank and have to stop, you'll be 5 minutes late. But if you forgot to charge the EV, now you're looking at several hours late (or give up and call a cab)…

So I have actually been in (close to) this situation.

i’ll address a couple of things though… First, since you plug-in every day at home it is very very rare for me to forget. Second, the total available range is still close to my old gas cars which means I need to have forgotten for many days in a row which in the last nine months has never happened.

BUT, I did say that I was low on energy on a day I needed to make a long drive…

Backstory was I was intentionally draining my battery over a period of about a week without charging (trying to recalibrate the gauges... very rare to do).

In the morning on a day I needed to make a three hour round-trip drive I realized I was at 20% power.

So I hightailed it to the nearest Tesla supercharger, plugged in, pulled out my laptop (I'm sitting on a giant battery... powering a MacBook is no issue) to get some work done, and 20 minutes later I was at 80% (enough for 200 miles - or my entire round trip).

So the power issue was caused semi-intentionally and entirely my fault but also it took very little time to solve it. It would be a bigger issue for somebody who isn’t near a supercharger (and no 220 line at home as they'll go 0->full overnight) but again it is very very easy to remember to plug-in at night and many/most people would generally need to forget to charge for at least three or four days before it becomes an issue.

Re: Tesla made $1.6 billion in Q3, is switching to LFP batteries globally

#63

Post by MrDunham » Sat, Oct 23, 2021, 2:53 PM UTC

cinntaile wrote: post #14

MrDunham wrote: post #11

Earlier quoted context omitted.

Completely agree. I had a thermodynamics teacher in college say “in the history of transportation we’ve never switched to something powered by lower energy density [than the previous mode of transportation]" in other words “energy density wins the day".* That was running through my head when I read they were switching to technology with lower energy density but, to your point and to the article's point, it’s really a…

He said that before we had EVs I presume.

Before we had good EVs (If I remember right electric vehicles at the time had something like 60 miles of range... I might be off, though. That was about 14 years ago)

Re: Tesla made $1.6 billion in Q3, is switching to LFP batteries globally

#64

Post by jjav » Sun, Oct 24, 2021, 8:07 AM UTC

MrDunham wrote: post #62

jjav wrote: post #55

Earlier quoted context omitted.

> But the secondary selling point was never having to go to a gas station again when I am just barely going to make the meeting and forgot to fill my gas tank the night before. Curious example since that's one of the drawbacks of an EV. If you forgot to fill the gas tank and have to stop, you'll be 5 minutes late. But if you forgot to charge the EV, now you're looking at several hours late (or give up and call a cab)…

So I have actually been in (close to) this situation. i’ll address a couple of things though… First, since you plug-in every day at home it is very very rare for me to forget. Second, the total available range is still close to my old gas cars which means I need to have forgotten for many days in a row which in the last nine months has never happened. BUT, I did say that I was low on energy on a day I needed to make…

> Second, the total available range is still close to my old gas cars

If the range is so huge, I see it might not be an issue.

We have a Fiat 500e, so forgetting to charge overnight (or if the timer didn't go on as intended for whatever reason) means a guaranteed crisis in the morning as there's no way to get to work.