So i did a long drive, Orlando - Miami and was at 100% charged when I left. The car prompted me saying doing full charges will reduce the life of the battery and i should only do Trip charged (brings it to about 278 miles). Should I only do full charges when I know im going to driving almost the entire duration of the battery, and for city driving just charge it up to 278miles (90%)
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When to fully charge?
- Thread starter agarabaghi
- Start date
IMHO, only fully charge when you're going to use some of the battery right away. Leaving the battery sit at 100% will slowly damage it.
-J
-J
swaltner
Active Member
Lots of threads on this because there are lots of opinions on it. Boils down to if you charge to 100%, drive it “right away”.
My personal choice is to charge to 80% every day. On the day before a road trip, I let it charge to 80% as normal. Sometime after that completes, activate a scheduled charge to 100% to start about 90 minutes before my desired departure time the next day. That way, the car is just finishing up the 100% charge when i’m ready to leave. When I arrive at the destination, set the charge limit back to 80%. Repeat for any multi-day trips and/or the trip back home.
My personal choice is to charge to 80% every day. On the day before a road trip, I let it charge to 80% as normal. Sometime after that completes, activate a scheduled charge to 100% to start about 90 minutes before my desired departure time the next day. That way, the car is just finishing up the 100% charge when i’m ready to leave. When I arrive at the destination, set the charge limit back to 80%. Repeat for any multi-day trips and/or the trip back home.
Ulmo
Active Member
This is what I finally decided:
Never charge to 100% or 90% (and even avoid charging to 80%), unless I:
- Know I will IMMEDIATELY drive the car afterwards at a reasonable rate (not too slow, not too fast), so that I can calmly (low C rate) use up the remaining energy. That means, no up-mountain headwinds on a freezing raining snowing day, because you could either (a) use too much energy too fast (also is bad for battery) or (b) get stuck and use too little energy (but that's another problem, freezing to death, so there is a built in exception to that example).
- Know I need it. Even if I know that I will immediately drive the car afterwards as in #1 above, I won't just charge to a high charge level "just because I can". I use experience (modulated by weather), the in-car nav, and EvTripPlanner.Com to figure out the reasonable battery charge levels. I try to keep the battery as near as possible to 55%, and since I have to drive the car, for long drives, I like 80% to be my maximum and 25% to be my minimum, but for very long legs, I allow obviously a bit more on both ends to make it to the destination. Remember: 0% will brick a battery, whereas 100% will damage a battery; better to charge to 90% and drive soon down to 10% and charge than to charge to 80% and run out before you get to the next SuperCharger and get stranded and brick your car (warranty doesn't cover that, car ruined). Same for 100% vs 0%, but if you're looking at a drive that uses the full range of your car from 100% to 0%, I suggest you have planned wrong, and you ought to insert a charge in that drive to bring it down to a nominal 75% to 30% drive (or 80% to 25% in outside cases (90% to 15% in even more extreme cases)).
The next part is important:
If you read everything I wrote above, you may be tempted to average the charge level and have your swing charge amount be something like 35%-80% every day, and since you are "avoiding charging to 80%", you don't worry about charging right away when you get back; that would be a mistake!!! Here's why: on a cold day you do two extra stops that you don't even remember (pick up some coffee, get a piece of chicken, a quick detour on the road because of construction, whatever), and you unwittingly arrive home with 14% state of charge. Then, by the "avoid high state of charge" rules you might have inferred from the above, you leave your car at 14% for the rest of the afternoon, evening, night, and morning, and then not only in cold will you have the secondary problem of trouble re-heating the pack to get its charge up and might never even be able to leave the next morning, but you will also have the primary problem of having damaged your battery by leaving it at a low state of charge; don't do that either.
Unfortunately, Tesla does not have a "double charging" and "tripple charging" option in their sheduling; what should be done is as soon as you park:
- Get the battery up to a safe minimum state of charge. (I am scared to state a %; I'm thinking 30% to 35%? Someone correct me. Too high, and electricity is too expensive. Too low, and it still is a low state of charge for too long.)
- Wait until electricity rates get lower and/or more electricity is available to charge the car, then bring the car battery up to about halfway state of charge.
- Stop charging again until the estimated start of charge time that you will be done charging right before leaving the next morning after completion of charge (to your target charge level) and start charging at that time.
You will see what I mean as you try to mete this out. After a while, you will get a feel and experience for what works best in your situation, and it will become, like I said, second nature. But this is all the stuff you should think of as you figure out what that should be.
Ideally, everyone charges at work in the day time with solar power when the sun is giving us energy and that solar energy is the cheapest; if that is your case, then this paragraph applies (note that for whatever reason, this is extremely rare, but in terms of civil planning, should be 100% of us, so if you have any decisions in the matter, that should be what you do). That would mean your pack is charged when there is enough heat to charge it, too. In that case, being home you could just bring the charge level up to a safe "overnight" charge level once you get home. The same ideas would be at play at work: charge at first to get the battery up out of low states of charge (nominally, most commutes would allow you to arrive at work with a "safe" level of charge, but some commutes are longer); then before you leave from work, another charge target for your commute home starting state of charge. You would target always having a 55% state of charge when you got home overnight, which is perfect. Plan for a higher state of charge before leaving work for errands, and top up to your target overnight charge level (say 55%) overnight (or earlier if very low state of charge when you arrive home) at home after extra errands or weather. The average of all this is that charging in the day from solar energy at work is best for the battery, best for cost, and best for you, since the two shifts when your car isn't at work are spent near perfect state of charge (around 50% to 55%), and the only shift your car is not at that state of charge is after you drove to work, the pack is hot, it's being charged, and when you're about to leave from work again. Like I said, for whatever reason, this opportunity is rare; you'd basically have to be your work's boss and owner, buy the solar panels and inverters yourself, have them installed, and wire the Level 2 EV chargers into the output of the solar system, and not exceed the solar system output. Another problem is that you would want to never exceed the sunlight available from such a system because that gets into expensive power overage charges from your utility, and for some reason, EVSE's (the chargers) don't automatically offer this avoid-excess-power setting, but they should. You can fenagle some solution some way.
If your commute means you have a lowish state of charge when you arrive home, then that probably means your commute is so far that you are using more than your full range of the car every day, then plan to charge up when you get home at the right time. I can't tell you what this would be. If I arrived home with 25% state of charge every night and that was during peak rates in the evening, I'd say ok, I'll wait until 11PM (PG&E EV-A cheapest rate time most of the year) and then target my leaving home state of charge for the next morning starting at 11PM. If I arrived home with only 15% state of charge, I'd be afraid to leave it like that if I arrived home at 5PM and lowest rates were not for another 11PM-5PM=6 hours, so I would probably right away as soon as I pulled in charge it full speed up to about 25% or so, then stop it (manually), then have scheduled charging do the rest at 11PM (most times of year), and finish at the "leave for work" state of charge % in the morning.
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ucmndd
Well-Known Member
A single charge to 100% shouldn't provide that message.
Periodic charging to 100% is no problem. Best to not leave it sitting at 100% for days.
And 80% maybe a better steady state number
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