Li-ion is not Lead acid. Li-ion batteries actually count charge cycles based on a 100 percent discharge even when it's summed over multiple sessions. For example, if you discharge a battery to 50 percent one day, charge it back to 100 percent, then discharge it 50 percent again the next day, that is counted as one "cycle" of the battery. If you are at 80%, then discharge to 70%, charge it back to 80%, and repeat that 9 more times, that is 1 discharge cycle. And referencing that chart, this means if you keep your DoD to 10% then you can do this repeatedly for a total of 4700 full discharge cycles (aka 47000 10% depth-of-discharges). So the shallower the discharge the best for a Li-ion battery.
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Li-ion is not Lead acid. Li-ion batteries actually count charge cycles based on a 100 percent discharge even when it's summed over multiple sessions. For example, if you discharge a battery to 50 percent one day, charge it back to 100 percent, then discharge it 50 percent again the next day, that is counted as one "cycle" of the battery. If you are at 80%, then discharge to 70%, charge it back to 80%, and repeat that 9 more times, that is 1 discharge cycle. And referencing that chart, this means if you keep your DoD to 10% then you can do this repeatedly for a total of 4700 full discharge cycles (aka 47000 10% depth-of-discharges). So the shallower the discharge the best for a Li-ion battery.
From everything I've read and all the consumer products I've used, mid cell/pack, frequent shallow cycles (vs deeper less frequent) can dramatically slow the degradation of the battery, maintaining peak performance for years to come. Tesla has made this about as intuitive as possible with the slider. the more time the pack spends at 50% the better (that's why the slider doesn't go below 50%).
Here's what I do: when convenient I leave the slider at 50% and top up just before leaving as needed. in the winter, this has the added benefit of warming the battery for better regen as well. to top up, I try and time it for enough of a charge do what I need to do and have me back in the stable around 40-50% SOC (I generally try and avoid going below 30% as a common practice). For longer trips, I err on the side of charging extra vs discharging deeper into the pack, especially when it's colder out. It's generally accepted that charging the battery to full is no big deal if you need to as long as you don't leave it there for long. you also need to pick a practice that is not stressful, so I suggest adjusting accordingly. we know that the main thing that kills batteries fast is heat, and Tesla has done a very good job with their temperature management system so you really don't need to worry, Tesla's taken care of the big stuff.
I plug it in every time I get home, even in between little trips. My schedule fluctuates a lot so I often don't know when I park how long it's going to be till I need to leave again or how far I will need to drive on the next trip. having it plugged in not only assures shallower charging cycles but it also assures it's plugged in so all I need to do to add to the charge is use the phone app. for a variety of reason's I have concluded that plugging in pretty much all the time when at home and keeping the slider default at 50% is the best practice.
Here's what I do: when convenient I leave the slider at 50% and top up just before leaving as needed. in the winter, this has the added benefit of warming the battery for better regen as well. to top up, I try and time it for enough of a charge do what I need to do and have me back in the stable around 40-50% SOC (I generally try and avoid going below 30% as a common practice). For longer trips, I err on the side of charging extra vs discharging deeper into the pack, especially when it's colder out. It's generally accepted that charging the battery to full is no big deal if you need to as long as you don't leave it there for long. you also need to pick a practice that is not stressful, so I suggest adjusting accordingly. we know that the main thing that kills batteries fast is heat, and Tesla has done a very good job with their temperature management system so you really don't need to worry, Tesla's taken care of the big stuff.
I plug it in every time I get home, even in between little trips. My schedule fluctuates a lot so I often don't know when I park how long it's going to be till I need to leave again or how far I will need to drive on the next trip. having it plugged in not only assures shallower charging cycles but it also assures it's plugged in so all I need to do to add to the charge is use the phone app. for a variety of reason's I have concluded that plugging in pretty much all the time when at home and keeping the slider default at 50% is the best practice.
I would definitely set the slider to 50% and leave it plugged in and monitor it via the phone app periodically to assure it doesn't dip below say 40%.
Well your first article explains how you should avoid large DoD. Then puts out a chart that shows while 50% DoD is better than as 100% DoD, 25% and 10% could be are actually worse than 50% and could even be worse than 100%. It seems doubtful to me that they are talking partial charge cycles. Not to mention that the graph would imply a 50% DoD is better across the board than a 25% DoD, or 10%. So I read it as 'complete discharge cycles'. Which is a common term when talking about batteries.
And using that logic I came up with an order of magnitude of improvement. 3750-4700 is an order of magnitude better than 300-500.
This is confusing language. But this graph is showing cycles as you presume, not what I was talking about. It serves no real purpose to do it this way as one can not gather meaningful data with an axis who's axes has a variable (not even linear variation) value. Remember this also a Pb-Acid battery, but it shows about 2x improvement at 1% DoD versus 100%. And a 15% improvement at 50% DoD versus 100%. So no not a order of magnitude. But at least constant improvement as DoD decreases.
Also in the same article there is this:
But also other verbiage that is somewhat contrary as well.
But for Li-Ion cells smaller DoD is better for battery health. Always charge as much as is practical. Personally I find charging at work a hassle, so I don't bother, even though I have the opportunity. I always plug in when home, but my timer only charges after 11:15pm, when really cheap electricity is available. So I only charge once a day.
The quote from that article above addressed this, when it said: "... it is typical for all cell chemistries including Lithium-ion."
Citation please?
probably too anecdotal for you but by applying shallow mid cycling, I got 5 years of pretty intense use out of my first iphone and 4 years so far on my lap top. It's very nice to replace a phone or lap top not because the battery crapped out but simply because you want to take advantages in improved technology. I work from home and can manage plugging and unplugging my phone and lap top, treating them as i do the Tesla and Leaf. my wife, in comparison, leaves both her computer and phone plugged in and max charged overnight. she's been through several i-phones and a couple lap tops in the same period. the average consumer would find it too tedious to do this the way most consumer electronics are configured but Tesla has apparently found enough evidence to create a very elegant solution for making it simple. I forget which update it was, but the addition of that slider was both very welcome and proof enough for me that it's worthwhile.
IMHO, if the price difference were substantial, use the HPWC or a clipper creek CS 100 and charge full blast, timing it to end close to the end of the off peak time, limiting the time the car sits at high SOC or just don't worry about the effect, charge when it's cheapest and enjoy your car :~). The battery management system on the Tesla S is well beyond anything battery university or anyone else has tested long term. I suspect that Tesla has tackled most of the biggies pretty well. the poll that plug in america did on long term ownership of the Roadster suggested that charging habits had little effect on battery life, that the roadster holds up pretty well over time, so don't stress out about this stuff, do what you can within reason and to the extent your circumstances allow.
I time it so that it ends about the time I leave. That leaves the battery at the lowest SOC for the longest period of time and warms the battery up before driving. No TOU here, but if there was my leaving time is before the TOU ends.
I try to avoid driving below 50% SOC except on trips, but then I don't worry about doing a range charge or running low. So far the lowest I've managed to go is 30 miles rated range left.
Haven't done any long term storage, but when I do I'll set the slider at 50%.
Assuming the Model S' battery management is at least as good as the Roadster's, it's really not worth worrying about overmuch. The two important things are to not leave the battery at either high or low SOCs for a long period of time. Kind of like health: If you smoke, then that's all you need to worry about. If you don't then there are some other things you can do.
A search != citation.
So far I've not seen anything supporting the premise you've put forth.
However I have provided some specific quotes that outline that two smaller charges roughly equate to a single larger charge of twice the amount (I.e.- two 30% charges equal one 60% charge).
Ok, off topic but I have a newbie question.
Is it cheaper to charge faster at 40 amps or slower at 25 amps. It's the same price (.14) no matter when I charge. Or does it matter?
I have a nema 14-50 with 50 amps, i was pulling 40 amps once plugged in but lowered it to 30 with the adapter issues.
Is it cheaper to charge faster at 40 amps or slower at 25 amps. It's the same price (.14) no matter when I charge. Or does it matter?
I have a nema 14-50 with 50 amps, i was pulling 40 amps once plugged in but lowered it to 30 with the adapter issues.
There might be some difference, but it's going to be small: $8.01 for a full charge instead of $8.00. Many of us charge at lower than 40 amps (I use 32) because it keeps the house wiring cooler, is easier on the grid (neighbours tend to get testy if you cause a power outage), and may aid in keeping the pack balanced (to really balance the pack, charge at 6 amps at 240V). Studies on the Roadster show that between 32 to 40 amps is the most efficient. Not yet enough data on the Model S.
cheaper to charge at 40amps than 25. thought not by much. However, it is MUCH cheaper than vs 110V. see this thread for details: Higher amp charging is more efficient??
Merrill
Merrill
So would like some input on the best charging cycles, if I read this post correctly you should do many small charges rather than fewer large charges. I do not commute and drive usually 10 to 15 miles 4 times a week. I have been starting at standard charge 175 miles and waiting til I get down to 50 or 75 miles and then charging. Should I be charging more frequently and for less time each charge.
yes.
don't wait. just plug it in every day and keep it plugged in. if you don't really drive far, then just keep your slider set to around 50-65%. if your at 60%, and you go run a few errands and come home and your at 55%, just plug it in. the shorter the depth of discharge, the better. three 5% depth of discharge cycles are better than one 15% depth of discharge cycle.
Merrill
Merrill
So if my thinking is correct you charge more at a less percent of total so you keep the soc from being always at a high state. So all this is supposed to help with long term battery degradation.
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