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But, how can they do that given the fact that the supercharger itself is limited to how much current it can put out? Especially considering that odds are (at least in populated areas) that you're going to be sharing the supercharger with someone else.
To me it makes way more sense to keep the charge profiles the same between the 60 and 75, and then simply top limit it. Ingineer did point out the drawback in that there is no 100% charge if it's top limited so how do they do cell balancing?
Canuck
Well-Known Member
I've been around long enough to know Tesla sales and service people are the last people to have reliable information.
Doing harm is one thing. Extending the life of your battery is another. We know that the best thing for lithium ions batteries, when it comes to longevity, is to cycle them around 50% as much as possible and, in fact: Lower charge voltages prolong battery life.
"Lower charge voltages prolong battery life and electric vehicles and satellites take advantage of this. Similar provisions could also be made for consumer devices, but these are seldom offered; planned obsolescence takes care of this."
But what if they leave some locked out at the top and some at the bottom? Isn't that possible? Then the no regen and not a dramatic drop off in SCing still make sense but you may actually be charging to 85% or 90% daily? Is that good for the battery to do consistently? That's at the top end of my "daily driving" slider for a reason.
So if 100% is 80% then you should arrive home with 20%, which has you cycling around 50% if you want to do what's best for your battery. But what if you usually arrive home with 40 or 50%? Is charging to 100% causing more degradation than charging to 80 or 90%? Yes. Is it an amount to be concerned about? I don't know, and maybe not. But what if your 80% is actually 85% or 90%?
People should understand that keeping more electrons in the battery than needed for cycles around 50% does degrade the cathode more than having less electrons in there. It's fine for you to tell everyone all is fine charging to 100% every day but it may not be and I don't see it as academic. I don't charge my 85 battery to 80% unless I need the extra range since I like to cycle it around 50% and I rarely come home with 20% left. If I had a 60, I'd keep the slider in the daily driving range unless I needed more range, or it was causing my cycles to go lower than cycling around 50%. All the research says that's the best for long battery life.
36 kw charging rate at 99% is crazily high!! 60 kwh Tesla is a bargain.Here was the top end at my local Supercharger just before I hit 100% the other day:
Superchargers are not that limited. Every 2 stalls of a Supercharger share a bank capable of delivering up to 135kW. Those are marked "A" and "B" on Superchargers. So when you begin the supercharging of a 14 module battery (75 or 60) you start out with 300V. So in theory you can got 430+ amps from the supercharger. However Tesla, in order to protect cells, starts supercharging on a depleted battery around 1.2C, so ~300 Amps, maximum. (If they started with 450Amps that would mean 6 amps per cell; 1.81C. Would drsatically reduce battery's life)
The increaes I'm talking about isn't drastic, maybe they added ~20-30 amps or sdded nothing at all. However they are more likely to start out with the same amperage but taper it way later. So a later taper on a 60 makes it reach 4.2V charging voltage per cell around 80% (60's 100%) and gets it there quicker compared to a 75 supercharging(early taper). If the intent was to fill all 75kWh of the pack like in 75, that ending part would take longer making no difference in the end. However with the 60 they don't care about the remaining 15kWh, so they just pump up to 80% as quickly as possible.
A 60D on 98% is getting 353V, 104 Amps. 353V divided by 84 groups in series is 4.2V, max voltage. However it is pulling a whopping 104 Amps. 104 Amps / 244Ah pack = 0,42C. When you take a look at when the old 85 pack was pulling that C rate from the Supercharger it turns out to be 81% SoC, another proof. (229Ah old pack *0,42C = 96Amps.) Also when the old packs reached max voltage of 4.2V they were pulling 0.34C, 80 Amps after 88%. 60D however reaches max. voltage with above 100Amp pull kind of proving they are applying higher overall c rates to get a quicker 80% (60's 100%)
I'm getting more and more sure about this.
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Chopr147
Active Member
Well, this issue was "settled" by consensus on another thread prior. I'm sure there will be another one. We love to argue the merits here 
Yeah sorry if I was adding old news. I was just stoked about the charge rate. Supercharged 3 times this weekend, and not once did my family get finished eating, etc. before the car was at 100%. That was really significant to me because the idea of only charging to 80% and then leaving the SC always made me a little conflicted.
32.5 kw charging rate at 100%, haha. It used to be extremely lucky if you get 4 kw at 99 or 100% state of charge.
@Ingineer, I'm a Chem.E. not an EE, so I had to refresh much of my recollection of E&M and circuits. But I'm having a hard time understanding how the charging voltage can equate to the storage voltage of the battery modules (which is what you are using to determine the cell voltage, correct?) if there is also a high current. All the SpC videos I've seen have the kW start high with maximum amperage and a coordinating voltage to apply the maximum kWs. The kWs then slowly drop as the amperage drops at a faster rate than the rate at which the voltage increases. If the applied voltage is viewed as electrical "pressure", similar to fluid pressure in a fluid-flow pipe system, then the applied voltage will always have to be greater than the battery voltage to have enough electrical "pressure" to push current (akin to gal./min.) into the battery, no? If I view it as a water pump filling a water tower, the pump can no longer fill the tower once the pressure in the tower equals the maximum pressure that can be exerted by the pump. So to continue to fill the tower, the pump has to be able to increase the applied pressure so that it is greater than that of the tower. Is it not the same for a battery?
I've tried looking on the internet for a couple of days, and I'm having a hard time finding anything clear on this. the closest I've come is this video showing a power source charging a capacitor where there is a multimeter connected to the capacitor showing the capacitor's voltage along with a display on the power source showing the voltage and amperage being applied by the charging power source:
This also matches the way an alternator charges a "normal" car battery:
Alternator & Charging System Checks (Alternator Testing)
The above seems to confirm that the voltage of the energy storage unit being charged (battery or capacitor) will always be less than the voltage being applied. As the storage voltage nears the applied voltage, the current will decrease. So holding the applied voltage at the maximum fill voltage of the battery allows the amperage to eventually drop to a "trickle" as the battery nears it's "full" voltage level. So, regardless of the voltage shown on the Tesla display, which is the voltage being applied by the SpC, it seems that the amperage reading (and thus also the kW reading) is the appropriate indicator for how close the battery is to full.
Please let me know if I'm missing something. I would also appreciate if you, or anyone else, knows of a good websites that explain how a battery charges in terms of applied voltage vs. battery voltage at a given time. I'm having a difficult time understanding how the two can be the same if there is current flowing into the battery. It that were the case, then it stands to reason that you would also have to be able to have a current flow from a lower-voltage source into a higher-voltage storage unit, and I just don't see how this is possible. Any enlightenment would be appreciated.
@Ingineer - Were you able to get some test 60s to test voltage? and do you still think it's not top-limited?
hybridbear
Active Member
gabeincal
Active Member
Reeler
Decade of Pure EV Driving
I had a 70D on order for February delivery. I was mad when Tesla wouldn't let me downgrade to a 60D. They are blowing out inventory cars such that I got a 75D for the price of a 60D in almost the same configuration I had on order.
I too will have a 60D when I set my charge limit to 80%!!!!!
I too will have a 60D when I set my charge limit to 80%!!!!!
I've had the car less than a week but have charged to 100% each work day so far. With 110 mile commute burning an ave of 325 Wh/Mile, I feel much better with a/100% charge. I live in the south bay & commute to the city. LMK if you want to connect to test out the voltages.
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