Is Tesla Going to Muck Up the Lith Cell

George S.

Well-Known Member
There's talk that Tesla wants to build a mega-factory, just for lithium cells. One thing under consideration is to make the cells different from the current standard, which I assume being is used by ebike companies:

In addition, the cells Tesla currently use are a standard model called an 18650. If the company has committed to a unique design from Panasonic, it would presumably be at least a couple of years before it went into use to allow Tesla time for other manufacturers to ramp up production of the design. Even with the new supply agreement, the forthcoming $35,000 sedan some are referring to as the Model E will require perhaps another billion cells annually on its own. The agreement announced today makes no mention of that vehicle.

Seems like the cost benefits of more cells, more capacity, would be higher if everyone was making a standard cell. It's still more capacity. It's a little hard to believe a Tesla has around 6,000 cells about the size of a AA battery.

All the trends are super-positive for ebikes. More capacity at lower cost, one way or another. Everyone wants the battery to weigh less, cost less, and have more range.

http://www.forbes.com/sites/markrog...uggests-sales-could-quintuple-within-4-years/
 

Court

Administrator
Staff member
Thanks for sharing this George. It's exciting to hear about new developments in the battery space, just this year (2014) Easy Motion is putting larger capacity batteries into their pack without changing the shape or design so it's backwards compatible. It would be neat if this was also the case for the Tesla batteries but ultimately it's still a step forward. It makes me think about how iPhones got a new charging standard recently (rendering old dongles obsolete) but improved the speed of connection and reduced the space required at the port (possibly also reducing potential for damage). I'm sure Tesla is thinking about these things for their cars.

tesla-18650-battery.jpg

I've also been amazed at the idea of 6,000 individual cells. Just seems like a lot of extra metal, plastic etc. to "contain" the batteries. Like all of those individually wrapped cells would be wasteful vs. one large cell or something. That said, I've heard Elon Musk speak about the battery and he calls out the increased stability and heat dissipation of individual cells which makes sense. He was making a similar suggestion to Boeing when they were having issues with fire.
 

Court

Administrator
Staff member
Wow! That's a pretty serious claim there... I would love to have this confirmed. How cool would that be :p
 

Ravi Kempaiah

Well-Known Member
Riide ebike said they use the same kind of braking used in Tesla Model S. :)
If Tesla were to team up with BMC, then it is an extremely positive sign. Normally, companies like Tesla tend to focus on high-volume markets.
 

George S.

Well-Known Member
Thanks for sharing this George. It's exciting to hear about new developments in the battery space, just this year (2014) Easy Motion is putting larger capacity batteries into their pack without changing the shape or design so it's backwards compatible. It would be neat if this was also the case for the Tesla batteries but ultimately it's still a step forward. It makes me think about how iPhones got a new charging standard recently (rendering old dongles obsolete) but improved the speed of connection and reduced the space required at the port (possibly also reducing potential for damage). I'm sure Tesla is thinking about these things for their cars.

View attachment 468

I've also been amazed at the idea of 6,000 individual cells. Just seems like a lot of extra metal, plastic etc. to "contain" the batteries. Like all of those individually wrapped cells would be wasteful vs. one large cell or something. That said, I've heard Elon Musk speak about the battery and he calls out the increased stability and heat dissipation of individual cells which makes sense. He was making a similar suggestion to Boeing when they were having issues with fire.
Court,

Tesla has figured out a lot of stuff that carries over directly to ebikes:
Two examples:
  1. run the battery down only 50% on each cycle, battery lasts 3X as long (kind of huge)
  2. charge to 90% each charge cycle, battery lasts 2X as long
Tesla engages #2 with a 'standard' and a 'range' charge. Don't know if anyone does that in ebikes.

Best,
George
 

Ravi Kempaiah

Well-Known Member
George,
You caught the main point. Thanks for sharing here.
Although Li-ion batteries don't experience memory effect like SLA's, there is something called SEI (solid electrolyte interphase) which affects the performance.
By constantly topping off the battery whenever it plunges below ~50% and stopping at ~90% will reduce the stress and build up of SEI.
It is applicable for phone and laptops as well.

 

Court

Administrator
Staff member
That's awesome Ravi, it would be neat to make an app for phones that stopped charging at 90% instead of 100% and also somehow alerted you when the phone was getting below 50%. Something like that could help to extend battery life and might become very popular... Do you know how to make apps by any chance? Ultimately the manufacturers could copy this and just build it right in but it would be nice to know you were helping people extend the life of their hardware :)

Maybe something like this app but it would actually cut off charging once it reached 90%. I wonder if that's even possible or if hardware features aren't accessible through apps?

[edit] It looks like this feature might actually already exist in phones. Check out this article and the quotes below:

Climbing out of bed, about to start your day, you unplug your new smartphone from its wall charger and quickly check your email. You’ve left it plugged in overnight, and the battery gauge shows 100%. After a quick shower, you remember that you forgot to send your client a file last night. You pick up your phone again, but the battery gauge now reads 90%. A 10% drop in 10 minutes? The phone must be defective, right?

Interestingly enough, improvements in battery management technology have compounded the average user’s perception of this problem. Older phones were rather inelegant in their charging behavior; usually filling the battery to capacity and then switching to a trickle current to maintain the highest charge possible. This offered the highest usage time in the short-term, but was damaging the battery over the course of ownership. As explained at Battery University, “The time at which the battery stays at [maximum charge] should be as short as possible. Prolonged high voltage promotes corrosion, especially at elevated temperatures.”

This is why many new phones will “lose” up to 10% within a few minutes of coming off the charger. The reality is that the battery was only at 100% capacity for a brief moment, after which the battery management system allowed it to slowly dip down to around 90%. Leaving the phone plugged in overnight does not make a difference: the phone only uses the wall current to maintain a partial charge state.
 

George S.

Well-Known Member
George,
You caught the main point. Thanks for sharing here.
Although Li-ion batteries don't experience memory effect like SLA's, there is something called SEI (solid electrolyte interphase) which affects the performance.
By constantly topping off the battery whenever it plunges below ~50% and stopping at ~90% will reduce the stress and build up of SEI.
It is applicable for phone and laptops as well.

Ravi,

Batteries seem like the future, but electricity in general. Given the wattages you need for something like an ebike, you could have an almost optimal situation in a couple of years. If you put 1.5 kilowatt hours on a bike, you could charge to the 90% level. You could assume most people would not cycle them down below 50%. And you could have a huge range. You seem to be saying battery cycling will be more robust, anyway.


It's funny how, in the early days, the car transformed things. We got highways, motels, suburbs, garages, factories. It was wealth generating wealth. And then the car became too central. The highways were hard to maintain, the suburbs were too far out. Kids couldn't bike to school, or walk to school. To me an ebike culture is more likely to solve some of these problems than a Tesla. Anything that makes Americans a bit more active.


I like the idea of a huge battery manufacturing plant in the US. But I hope Musk is not believing his own very optimistic forecasts. Tough world.

George
 

George S.

Well-Known Member
That's awesome Ravi, it would be neat to make an app for phones that stopped charging at 90% instead of 100% and also somehow alerted you when the phone was getting below 50%. Something like that could help to extend battery life and might become very popular... Do you know how to make apps by any chance? Ultimately the manufacturers could copy this and just build it right in but it would be nice to know you were helping people extend the life of their hardware :)

Maybe something like (Link Removed - No Longer Exists) but it would actually cut off charging once it reached 90%. I wonder if that's even possible or if hardware features aren't accessible through apps?

[edit] It looks like this feature might actually already exist in phones. Check out this article and the quotes below:
Court,

They could make the darned battery user replaceable.:rolleyes:

George