Road tripping and charging to 100%

[dweeks]

An efficient trip will have you charging to 100% when charging overnight, and to less than 80% in Superchargers along the way.
This is because charging speed will taper as your get closer to full.

You will get a note on your display if Tesla determines you have been charging higher than is good for your battery. You can adapt another strategy at that point.

I travel on business from Flagstaff, AZ to Phoenix and back about three times a month. Airline trip and the car is parked for 4 days usually.

2017 S100D.

Due to the altitude change, you can't make it round trip even if you leave Flagstaff at 100%.

I charge to 100%, drive the 154 miles to PHX, using about 125 rated miles. Parked for 3-4 days at the airport I lose several percent due to vampire loss; more when it's really hot or really cold in PHX, due to the BMS cooling or heating the battery while parked.

I stop at Cordes Lakes Supercharger, which is almost exactly halfway back. I usually have about 30% left. I only need to charge for 5-6 minutes to be able to drive fast uphill to Flag and still have 35 miles in reserve.

If I left the house with less than 100%, I'd have a longer charge at Cordes on the return.

 

[f205v]

I use 2 different strategies for long road-trips, depending on the time of the year.
Winter: charge to 100% before leaving, then charge what's needed for the next leg based on abetterroutplanner. Charge again to 100% during night.
Summer: only charge what's needed for the next leg, never 100%

There are 2 reasons for that: 1) winter range is 20% less than summer range, so starting every morning with 100% gives me peace of mind. 2) Battery degradation is worst when you combine high state of charge and temperature, therefore I avoid it as much as possible in hot days.

 

[doghousePVD]

I'm not sure why so many people think this, because it's easy to show this is always false. It will ALWAYS save you required charging time to depart for the day with a higher state of charge.

Scenario 1: Charge to 100% overnight, arrive at first charging station with 30% left. 80% charge needed to reach next charging station. Charge from 30% to 80%.

Scenario 2: Charge to 90% overnight, arrive at first charging station with 20% left. 80% charge needed to reach next charging station. Charge from 20% to 80%.

It might be small, it may even be inconsequential if you're planning for a longer stop anyway, but you can say with absolute certainty that all other things being equal, it takes longer to charge from 20% to 80% than it does to charge from 30% to 80%.

Most of the time when I stop at a SC on a trip (not local), it takes me (and family) longer to replenish the coffee and bio-break than the minimum required to continue the trip to the next SC. I plan all the stops using A Better Route Planner. On some long trips it saves an hour or two over the Tesla planner.

Charging all the way to 80%+ is often slower than making quicker stops to a lower charge level. Charging 10% to 20% is quick while 70% to 80% is slow.

 

[David Farmer]

Cars that are never charged to 100% get packs that are out of balance. Each battery has a slightly different internal resistance, and the BMS can only properly balance the pack when it is charged near 100%. I read somewhere that Elon recommended that the the pack should be charged to 100% a few times per year. Charging at a super charger is too fast for the BMS to be able to balance the cells, so charging to 100% at a supercharger should be avoided.

 

[Jonathantuba]

I don’t think charging to 100% causes any problems if you leave soon after. I have done 45k miles and often charge to 100% on frequent roadtrips. I have only lost 5 miles range so far which is quite normal and to be expected

 

[mswlogo]

I have no issue with 100% but if I do, I immediately use it. I would not recommend like charging to 100% and leaving it over night. How soon is “use it soon” is anyone’s guess. So I error on the side of zero. It can be little tricky targeting 100% to exactly when you want to leave. You could use the targeted time scheduling to finish when you plan to leave.

But I almost never leave exactly when I want on long trips. Ugh.

 

[David Farmer]

I agree, I was just encouraging the occasional full charge at a slow rate. I don't think that super charging to full balances the pack, and if the pack were out of balance, could possibly over charge an already high cell. The BMS is probably good enough to stop the charge when the first cell got to max charge, but then the rest of the pack would not be fully charged resulting in less than max range.

 

[dbldwn02]

I charge to 90-95% overnight at home/destination chargers and then kick it up to 100% when I wake up. It warms up the battery. I'm not worried about regen, but a warmer battery gets significantly lower watthours per mile.

Note: I only do this for road trips. Personally I only charge to 60-80% daily and 100% a couple times a year.

 

[TFCooper3]

Here's the stats on my scenario: 127 miles from home to the first supercharger, which will take me from 100% to 20% charge. I will spend 21 minutes charging to 68%. If instead I charge at home to 95% and arrive at the charger with 15%, I will have to spend 23 minutes charging. So I can avoid charging to 100% by spending two more minutes charging at the supercharger.
Am I better off just charging to 95% at home before departing and waiting two more minutes at the first charger(not really, because I doubt I will be ready anyway)?

Since it's at most a couple of minutes either way, this is really an academic question, but an interesting one. I'm guessing the lion sleeps better on a 95% charge. That's what I'd try, anyway.

 

[mswlogo]

I agree, I was just encouraging the occasional full charge at a slow rate. I don't think that super charging to full balances the pack, and if the pack were out of balance, could possibly over charge an already high cell. The BMS is probably good enough to stop the charge when the first cell got to max charge, but then the rest of the pack would not be fully charged resulting in less than max range.

I don’t think SC to 100% vs Home Charging to 100% makes any difference. SC throttles WAY down as it moves into battery balancing. Like 1kW for the last 1%. And that last 1% takes forever like 30 minutes or more. And if you slow charge at home which really takes a long time your more likely to let it sit at 100% longer than at a SC.

 

[faughtz]

Cars that are never charged to 100% get packs that are out of balance. Each battery has a slightly different internal resistance, and the BMS can only properly balance the pack when it is charged near 100%. I read somewhere that Elon recommended that the the pack should be charged to 100% a few times per year. Charging at a super charger is too fast for the BMS to be able to balance the cells, so charging to 100% at a supercharger should be avoided.

Authoritative source?

 

[animorph]

Before a road trip I charge to 90% the night before at my normal charging time. About 2 hours before we leave I start charging towards 100%. We leave whenever we're ready. This avoids letting the car sit at 100% for fours. Worst case it saves a few minutes at the first Supercharger.

I've read articles (Battery University?) about battery tests where batteries were stored for a year at various charge levels. A battery at 100% charge for a year has a large capacity degradation, even without cycling it. That's what we're trying to avoid. Who knows if a few 100% charges just before a drive has a significant effect.

On the road I'll follow the same 100% routine if it's convenient, like moving to the Supercharger when we come down for breakfast at a hotel. Otherwise it's 90% if we're not waiting in the car, or just enough to sit overnight and make the next Supercharger if there's no charging at the hotel.

 

[David99]

After Tesla severely crippled my battery and as a result my car's road trip abilities, I would recommend charging to 100% only when needed. Tesla is preventing my car (and many others) from charging to 100%. This means that's what they see as the most damaging and dangerous. I have charged to 100% many many times over the last 6 years. If I could go back in time I would probably only charge to 90% in general and only use 100% when the range is absolutely needed. Would that have prevented Tesla clipping my battery? I don't know for sure but I think so.

 

[A-Wimoweh]

I just wish Tesla would be more communicative about the root cause of these actions they have been taking lately. It might allow us with newer cars to modify our driving and charging behavior such that caps can be avoided.

 

[beatle]

I'll only charge to 100% if I'm on the edge of making it to my first stop. This paid off on my last trip. I charged to 100% and made it to my first SC with 17%. I was predicting I'd have plenty of juice, but there was a huge headwind for over half the distance to the first SC. My efficiency dropped into the low 70s whereas it was normally in the low 80s. I think I may have still made it to the SC even if I didn't charge to 100%, but the peace of mind was nice.

Of course I could have just stopped at an earlier SC and been okay, but the extra capacity was welcome to stay on track. If I'm targeting an arrival 25% SoC when leaving from 90%, I'd say that's enough cushion for me and I wouldn't bother charging to 100%.

 

[A-Wimoweh]

I think I'm just gonna charge to 90% instead of my usual 80% for this trip. Temps will be below freezing, but the roads should be clear and the weather nice. Not worth using up some of my 100% charges when there is really no danger of not making it due to lack of chargers, and I'm not really pressed for time.

 

[David Farmer]

Authoritative source?

About what? The unequal internal resistance, or lack of balancing while super charging?

Here is a link about internal resistance. If I find a good description of balancing I will try to link that here.
Internal resistance - Wikipedia

Battery balancing - Wikipedia
Note the reference to a Utube video that has a good description in the text, but the video is just a reading of the text.

More on balancing:
Battery Power Online | Why Proper Cell Balancing is Necessary in Battery Packs

 

[Zooomer]

charge to 95%, call it good

 

[gigawatt1010]

I have a 2016 Model S60D (yes, six-zero) with a whopping 205 ish miles of range, full charged. I've had it since new, and it now has a little over 100k miles, in 3 years. I put about 100 miles per day in my daily commute. We've driven it to Key West from NY, twice. Driven it up to Maine from NY. Driven it in many road trips.

I always charged 100% and just ignore the warning about battery degradation. 3 years, 100k miles later, it's still fully charging at 204/205 sometimes, 206 miles. Never really had range anxiety and wouldn't hesitate to take it on another road trip, but road trips are now relegated to the Model X.

I guess my lack of degradation is due to the fact that my Model S 60D is actually a 75D that is software limited. So I guess YMMV.

 

[VikH]

I charge to 90-95% overnight at home/destination chargers and then kick it up to 100% when I wake up. It warms up the battery. I'm not worried about regen, but a warmer battery gets significantly lower watthours per mile.

Note: I only do this for road trips. Personally I only charge to 60-80% daily and 100% a couple times a year.

I have started doing this as well. Good advice.

I have a 2016 Model S60D (yes, six-zero) with a whopping 205 ish miles of range, full charged. I've had it since new, and it now has a little over 100k miles, in 3 years. I put about 100 miles per day in my daily commute. We've driven it to Key West from NY, twice. Driven it up to Maine from NY. Driven it in many road trips.

I always charged 100% and just ignore the warning about battery degradation. 3 years, 100k miles later, it's still fully charging at 204/205 sometimes, 206 miles. Never really had range anxiety and wouldn't hesitate to take it on another road trip, but road trips are now relegated to the Model X.

I guess my lack of degradation is due to the fact that my Model S 60D is actually a 75D that is software limited. So I guess YMMV.

Your 100% isn't actually 100% though. You can charge to 100% everyday and be fine.