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Just want to clear up my language parsing.
Are you saying "the speed that an individual cell can be charged determines the pack charge rate"? (Interpeting statement as rhetorical question) If so, I agree.
pz1975
Active Member
Tesla has launched a stylish $45 portable charger for your phone
Now we see why there is a bottleneck in getting cells for the M3.
Now we see why there is a bottleneck in getting cells for the M3.
Gerardf
Active Member
Yes and no
Yes, the bottleneck are the cells. On the other hand you can do some tricks like putting more cells (or two 400 V packs) in series (so the charge current in each cell stays the same, but you get to a higher 800V pack voltage and thus more energy). Also has the advange of lighter charge cables.
Nothing would stop you then from switching these packs that are in series during charging in parallel.
Guess I now just increased the confusion ?
Optimistic Overview of Tesla
I don't follow this gentleman's offerings and apologies from lifting from SA, but here's a winner. Nothing new and mostly derivative, but nice overview of why most of us longs are hopeful.
Tesla: Not Approaching Terminal Decline - Tesla Motors (NASDAQ:TSLA) | Seeking Alpha
I don't follow this gentleman's offerings and apologies from lifting from SA, but here's a winner. Nothing new and mostly derivative, but nice overview of why most of us longs are hopeful.
Tesla: Not Approaching Terminal Decline - Tesla Motors (NASDAQ:TSLA) | Seeking Alpha
JRP3
Hyperactive Member
No. Two 400 V packs of X amp hours in parallel or series is the same amount of energy and charge time is not affected.
Yes and no
Yes, the bottleneck are the cells. On the other hand you can do some tricks like putting more cells (or two 400 V packs) in series (so the charge current in each cell stays the same, but you get to a higher 800V pack voltage and thus more energy). Also has the advange of lighter charge cables.
Nothing would stop you then from switching these packs that are in series during charging in parallel.
Guess I now just increased the confusion ?
Two packs in series only has more energy because you have two packs. Two packs in parallel have the same energy.
(2*400V*10Ah = 400V*(10Ah *2)
But yah, in series drops the charging current, which drops cable losses.
Boosting pack voltage also allows high motor RPM for a given winding..
Edit: @JRP3 types faster than I do.
JRP3
Hyperactive Member
Bob Lutz ranting again Former GM Exec Bob Lutz Says Tesla is 'Going Out of Business' » AutoGuide.com News
Yuri_G
Member
Someone should teach Bob about the S curve.
1200 more Model 3 VINs registered.
Model 3 VINs on Twitter
I don't think Tesla Semi has either an energy density or C rate design challenge. I think the design challenge is limiting degradation to enable enough battery cycles needed to do a million miles.
JRP3
Hyperactive Member
A 500 mile pack at 2000 charge cycles provides 1 million miles. The existing NCA chemistry could probably do that, if they are using NMC chemistry used in Powerpacks it's good for 5000 cycles.
Indeed! You hit that slow pitch out of the park and into the parking lot! Well done.
larmor
Active Member
That gives even more credence to this concept, as the military tech is at least 10 to 20 years ahead of what is currently available....
Not exactly. How fast a battery charges has much to do with the charging voltage up to the max charging rate the cell can chemically handle. A good example is the way car batteries can be 'trickle' charged. It is the charging electronics that determines the battery charging speed. Tesla Superchargers are designed and programmed to vary charging speed based on how much energy is already in the battery. It charges the battery at the fastest rate Tesla wants to cell to be charged at (to avoid degrading pack life) up to some % and then it begins reducing the charge rate as the battery gets progressively closer to 'full'.
But yes, the battery chemistry is the underlying factor in how fast it can be charged, should be charged, etc. Note: If the amount of power demanded by the # of cars charging at a location is more than the location can handle, then those cars are going to charge more slowly than they otherwise would at a location with more than adequate power to meet the load.
Bob Lutz knows about the S curve. He is just a jerk bad mouthing a strong competitor. He has been the Chairman of VIA Motors since 2011, and also he co-founded VLF Automotive in 2013. Both are EV companies. Of course he hates Tesla. I am not surprised media never mention that he is a competitor of Tesla.
I suspect he shorted TSLA too a few years ago. It's not going well for him.
Something occured to me, and it may have already been mentioned, but I thought I'd throw it out there:
The name "Megacharger". I think the name has been chosen quite specifically, like the "Gigafactory". "Gigafactory" was chosen because the factory is the first to produce more than 1 GWh of batteries per year.
In the same naming scheme, it makes sense for "Megacharger" to mean it's the first vehicle charger to exceed 1 MW. Whether that is 1.6 MW, 2 MW, 2.5 MW or 3 MW, who knows? But at least more than 1 MW.
The name "Megacharger". I think the name has been chosen quite specifically, like the "Gigafactory". "Gigafactory" was chosen because the factory is the first to produce more than 1 GWh of batteries per year.
In the same naming scheme, it makes sense for "Megacharger" to mean it's the first vehicle charger to exceed 1 MW. Whether that is 1.6 MW, 2 MW, 2.5 MW or 3 MW, who knows? But at least more than 1 MW.
Thumper
Active Member
Wild guess, Bob Lutz dies before Tesla.
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This is said with malicious intent, he wants them to fail probably because
He has something to gain . If you are looking for a motive,
Follow the money.
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