Soolim
Member
for 80 miles to SpC I will charge to 90% at home so that regen braking still works for the first few miles. A 100% SoC prevents the regen from working.
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Should I charge to 100% (night before trip) if my first supercharger stop is only 80 miles away?
- Thread starter GasKilla
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Canuck
Well-Known Member
I don't get your point. I know it charges faster at the bottom of the battery but when it starts to get full, it charges the same regardless of whether you put the electrons in at home or at the supercharger. So why would he want to arrive with a low battery and spend time at the supercharger when he could have got the bottom electrons at home and not wasted time hanging around a supercharger?
I guess that depends on your definition of "harm". Lower charge voltages prolong battery life. Cramming every last electron into a lithium ion battery will degrade the cathode it faster than if the battery was sitting at 50%, which is ideal for the life the cathode. But it won't do much "harm" if you drive the car right away, and the worst thing about a full battery is combining it with temperature, which Tesla controls so no worries there, but even just having it full is not ideal. That's why you should plan to have it charge to 100% right before you leave and try to not let it sit at 100% for extended periods of time.
I go to my cabin a lot and the supercharger is about 100 miles away. What I do, is charge to 90% overnight, then when I get up I slide the app to full charge while I shower and get ready to leave. It's usually under 100% by the time I leave but I don't need 100%, and it still makes my time at the Supercharger less while getting enough electrons for the final leg to my cabin.
iwannam3
Active Member
Isn't it a good idea to exercise the brakes from time to time? I remember reading about a guy who got a huge bill because his calipers and rotors were rusted from salt and lack of use?
if you read the original post, he's only 80 miles from his first stop, if he leaves home with a full charge he'll spend more time at the SpC charging the upper portion of the battery. the next SpC is 125 miles or so away, if you only charge enough to reach the next SpC, running the bottom of the battery your stops will be shorter since the lower portion of the battery charges faster than the battery when it is fuller.
I would charge 100% at home (no time penalty b/c overnight) and then drive extra fast to the first stop to reduce travel time, and lower state of charge for faster charging! So many variables. But for an 80 mile jump, it probably doesn't matter. Basically any choice will be within 5 mins of any other. Traffic lights will probably have a bigger impact than the difference between departing with 90% or 100%.
Yes and no. Yes, it charges slower at higher states of charge, but if you start a leg and charge sequence with more charge, you'll always have more charge after a given amount of time at the SpC. Not sure if that makes sense without an example...
In the OP's case, he's starting 80 miles from a SpC with a 240 mile rated 70D. If he charges to 100% and gets rated mileage, he'll arrive at the SpC with 160 miles remaining, at 66%. If he charges to 80% (192 miles), he'll arrive with 112 miles left, ~47%.
The car will certainly charge faster at 47% than at 66% - here's a time lapse video Bjorn put together. In it, when the 70D hits 179 km (112 miles) rated range, it is charge at 80 kW. At 256 km (160 miles, it's charging at 54 kW)
80 kW is obviously better than 54, right? But here's the thing:
If he leaves the Supercharger after 10 minutes, in the first case he'll have 236 km (148 miles) of rated range available for the next leg. In the second, he'll have 298 km/186 miles.
(Both based on Bjorn's time lapse. I had to stop with ten minutes because his charge limits were relatively low and the car stops charging less than 15 minutes after it reaches the 160 mile point.)
He gained more miles in the ten minute stop by arriving with less charge (36 miles vs 26 miles) - but he still has less overall range to work with.
The "arrive at lower states of charge" discussion is about sustained trips and was intended to be "don't waste time charging to higher levels than you need at a SpC in the middle of a trip, because you'll charge faster lower in the battery" - if the charging time isn't delaying your trip (happens before you leave, while you sleep, or while you eat,) from a time standpoint you're always better off taking the free miles.
gavine
Petrol Head turned EV Enthusiast
Good point, but could be moot if he lives close to the highway.
Same goes with range mode in the winter. No need to use kWh's warming the battery to allow regen, if you're jumping right on the highway anyway.
scottf200
Well-Known Member
I charge to 90% then about 2 hrs before I am planning on leaving I set it to 100% trip charging. I adjust the amps until the estimation time left to charge matches my time to departure. This has worked excellent for me and I don't need to leave my car at 100% for any length of time.
Why or why isn't there are time to depart setting in the car when you set it to trip and just let the car calculate (adjust amps) until it matches your time to depart?!?
Let me get this straight. In a theoretical world where every SC on a trip was 100 miles apart (and all other factors - weather, terrain are equal). I would be 'recharging' 100 miles at each stop. So charging time would be quicker if I always arrive with a 10 mile range left than with a 90 mile range left.
Basically, this has been what I was told by Tesla.
Basically, this has been what I was told by Tesla.
gavine
Petrol Head turned EV Enthusiast
But, you wouldn't "need" to add 100 miles at the SC if you started with more in the tank. Ideally, you want to reach your destination with a low state of charge which would mean that you didn't spend more time charging than necessary.
Yes, given that my destination is the next SC at 100 miles away, more in the tank at the current SC would make my charge time go slower.
This assumes an infinite trip where each SC is 100 miles down the road.
This assumes an infinite trip where each SC is 100 miles down the road.
This is true. But it is also a limited example.
If you have enough charging time when you aren't waiting for the car, you might get to skip a Supercharger entirely.
The point of the discussion is the you don't want to wait for the car to charge up to arrive with 90 miles of range - you'll lose less time if you charged to arrive with ten miles.
If you aren't waiting on the car, charge as much as you can so you won't have to wait for the car later. (With the usual caveat about not leaving the car sitting at 100% for long periods.)
In context, my definition of harm is any meaningful difference in degradation. There is absolutely nothing to show that sensible range charging practices on a model s (and ostensively, a model x) have any negative effects. Specifically, that means range charging only for longer trips, and trying to minimize the time spent at higher SOCs.
I realize we're basically saying the same thing, but too often I see owners swing pendulum way to the conservative side of the range charge discussion, and I'm trying to pull it back a bit. There shouldn't be any FUD for tesla owners regarding range charging. This thread is explicit proof that there is FUD.
Yes, perhaps I could charge higher to skip the next SC. But the time it would take to charge that higher amount above what is necessary to reach the upcoming charger would be slower than charging at the next charger to reach the second.
Rough examples... Chargers are 100 miles apart.
A. I'm charging from a low SOC to 120 miles (my distance to next SOC plus a buffer).
B. But if I charge to 240 (my distance to the second charger plus a buffer) it will take, not twice as long, but about 2.8 to 3.2 times as long.
However, if I stayed on track, it would be 2 charging sessions from a low SOC, both charging quickly.
From scenarios above
A. Drive 60 mph 200 miles (3 hours 20 minutes total). Charge twice about 20 minutes each stop.
Total 4 hours.
B. Drive 60 mph 200 miles (3 hours 20 minutes total). Charge once from low SOC to 240 miles about 1 hour 5 minutes)
Total 4 hours 25 minutes.
Rough examples... Chargers are 100 miles apart.
A. I'm charging from a low SOC to 120 miles (my distance to next SOC plus a buffer).
B. But if I charge to 240 (my distance to the second charger plus a buffer) it will take, not twice as long, but about 2.8 to 3.2 times as long.
However, if I stayed on track, it would be 2 charging sessions from a low SOC, both charging quickly.
From scenarios above
A. Drive 60 mph 200 miles (3 hours 20 minutes total). Charge twice about 20 minutes each stop.
Total 4 hours.
B. Drive 60 mph 200 miles (3 hours 20 minutes total). Charge once from low SOC to 240 miles about 1 hour 5 minutes)
Total 4 hours 25 minutes.
Just to clarify, that's not the situation that started this thread. The time it takes for the OP to get the initial charge--at home, the night before the trip--is free. It doesn't count toward total trip time. Regardless if OP can skip the first charger or not, total trip time will be lower if the car rolls out the garage with 100%. It doesn't matter how many miles are in the battery at the first charge. Its always faster to range charge at night.
You're talking about legs between superchargers, which is a different story. If superchargers are 100 miles apart, total trip time is minimized by only charging back up to 100miles (plus reserve) at each station.
roblab
Active Member
Really? You spend all this discussion time on how to save a few minutes. You ever choose Mickey D's over a nicer restaurant so you can save a few minutes? You never go to town, because you might have to wait at a red light? C'mon. Waiting a few minutes is not the end of the world. Even buying gas at Costco took time, and you had to pay for it! Oh, well.
Everyone can make up their own mind on the minutes that are important and the minutes that are not. For me, supercharger trips usually mean I'm going to see loved ones.
That you judge my preference of family over supercharging is a bit poor form.
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