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Using batteries at the Supercharging stations has been an interesting plan for some time. The only issue of course is the cost of the batteries, but I wonder if Tesla could use older used batteries that have been swapped or turned in for new ones?
Batteries certainly lose capacity both due to cycles and time, but if they are cheap enough, there's not a lot of downside to just stacking up more of them for a stationary application. The Li ion aging curves I've seen seem to show a decreasing rate of charge loss over both cycles and time, and with a steady supply of used batteries, perhaps use at Superchargers for a few years could be a step in the battery life cycle before final recycling.
Batteries certainly lose capacity both due to cycles and time, but if they are cheap enough, there's not a lot of downside to just stacking up more of them for a stationary application. The Li ion aging curves I've seen seem to show a decreasing rate of charge loss over both cycles and time, and with a steady supply of used batteries, perhaps use at Superchargers for a few years could be a step in the battery life cycle before final recycling.
Francis Lau
P-1456
It is funny you mention this, I met a Tesla employee that works in the Fremont factory and he said that they don't waste anything and that they use battery packs that not good enough for the MS for the solar-enabled supercharger stations.
stopcrazypp
Well-Known Member
Just to temper this a bit, here's the direct quote from Straubel:
It's certainly possible. 10 minute charging was demonstrated 6 years ago by charging a 35kWh Altairnano pack with a 250kW Aerovironment charger.
http://green.autoblog.com/2007/05/3...ssfully-quick-charges-altair-nanotechnologie/
It's certainly possible. 10 minute charging was demonstrated 6 years ago by charging a 35kWh Altairnano pack with a 250kW Aerovironment charger.
http://green.autoblog.com/2007/05/3...ssfully-quick-charges-altair-nanotechnologie/
Vger
Active Member
I also recently heard from a very credible and experienced Tesla employee that the cars are capable of charging a lot faster than the SuperChargers are currently enabling. In fact, he implied that the existing SuperChargers are not yet at their limits-- that they can in principle go above 120 kW. He stated that Tesla is ramping up the SuperCharging gradually to collect data from the cars and their batteries and make sure they are on solid ground each step of the way.
It is nice to be riding a fast horse in this derby!
It is nice to be riding a fast horse in this derby!
stopcrazypp
Well-Known Member
The superchargers are rated for up to 133kW input if you look at the label (480V*160A*3^0.5). Apparently this is true of both the 90kW and 120kW versions (some people who have taken a picture of the UL label for the older 90kW version say the ratings are the same for both).
The bottleneck will probably be the battery or the connector/connector wiring as the superchargers can always be upgraded independent of the cars, but those two can't be.
Charging in 5 minutes equates to a 6C charge rate.
I wonder what changes in battery chemistry will need to be in place to accommodate that... it's pretty aggressive for most lithium ion cells I know about... but it's interesting to contemplate what sort of special sauce Tesla is aware of coming down the pike.
stopcrazypp's post is on-point I suspect. I'd bet we are close to the limits of what the conductors in current[1] cars are capable of handling at the 120KW rate already...
[1] See what I did there?
I wonder what changes in battery chemistry will need to be in place to accommodate that... it's pretty aggressive for most lithium ion cells I know about... but it's interesting to contemplate what sort of special sauce Tesla is aware of coming down the pike.
stopcrazypp's post is on-point I suspect. I'd bet we are close to the limits of what the conductors in current[1] cars are capable of handling at the 120KW rate already...
[1] See what I did there?
Does anyone know what the wire gauge is on the cables from the charge port to the battery? (The DC connectors). This would tell us the maximum current that can go through and figure out the max power that can be delivered based on the battery voltage.
Can't see the designations, but some pics of it are visible on Al Sherman's Charge Port thread.
While beefy, I'd guess that they aren't large enough to handle much more than the 300ish amps or so that a 120KW supercharger is likely to supply...
Current lithium polymer batteries for r/c can handle at least 12C charging. That property however seems tied to cells with high discharge rates also (up to 50 or 70C) - and to increased weight as well. I'm pretty sure the tesla panasonics aren't designed for that sort of discharge rate.
But at least we know it is possible, today, albeit at likely reduced energy density.Also 6C rate for example wouldn't yield 5 min full charge. Current tapers off rapidly after a point. I would think you would actually need around 12C rate for a 5min full charge.
bollar
Disgruntled Member
Yes. I think Tesla considers an optimal charge to be ~80% at the Supercharger. On the new SC page, they mention that charges beyond 80% are much slower than the first 80%.Ah yes... Good point about the tapering... Although Tesla seems to refer to the 90KW SC's as being able to charge the car in "about an hour", so perhaps George is using "idealized" numbers...
Supercharger | Tesla Motors
Isn't 1 hour divided by 5 minutes equal to 12, not 6?
i.e., shouldn't you need at least 12C to get from empty to full in 5 minutes?
stopcrazypp
Well-Known Member
Right you are... as stopcrazypp states, he mentioned 10mins as the upper limit, and that's what my feeble brain latched on to despite what I wrote. Thanks.
So a 12C charge rate is even MORE aggressive... will be interesting to see if that actually develops
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