What Wall Charger to Buy???

[HaulingAss]

A battery isn't considered cycled until it goes below 50.

And as pointed out, even at 350Wh/mi that's over 11k miles per plugged in 8 hours a day. That's more than enough for the average driver, even with some battery heating or cooling from the wall.

Cars on average spend 95% of the time parked. The median commute is 41 miles. Stay plugged in twelve hours out of the day on average and you have over 3k of extra miles charged per year, assuming no days off.

Don't underestimate the lowly Level 1 charge point.

-Crissa

The battery ages in fairly direct proportion to the power provided, all other things remaining the same.

This means each battery "cycle" is considered relative to the capacity of the battery. If a 100 kWh battery is dicharged and charged 10 kWh ten times, that is one "cycle" for general purposes.

There are a lot of small things like additional battery cycling and the fact that the car will be awake more hours when only using 120 volt charging that are less than ideal compared to more robust charging currents.

Less than optimal solutions can be made to work, they are just not optimal!

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[ajdelange]

So what's your take on the set up/ voltage requirements to be ready to welcome home your new CT???

It just occurred to me that an important aspect of the answer to that question is Tesla's new policy of NOT including a UMC with its vehicles any more so that if you don't have EVSE set up at home you will not be able to charge at home from any outlet in your house be it 120 or 240. Keep this in mind when (and if) the CT actually ever starts delivery. By that time Tesla may have reversed the policy. I hope so because I think everyone should have a UMC with the adapter kit on board whenever he is out and obout in his Tesla. Now I admit that I am on my second Tesla and have never used the UMC (except for some tests yesterday to rebut the absurd comments made about it at 120V) and as the public charging network expands it definitely provides less security but I still like knowing it's in the frunk.

While discussing the UMC I'll mention a feature of it that has not been mentioned here (that I recall) and that is that it accepts 16A from a 20A 120V receptacle. These seem to be required in some parts of a house (such as kitchen and garage) these days and are distinguishable from 15A outlets in that the neutral "pin" is T shaped rather than I shaped as in a 15 A receptacle. That allows them to accept the NEMA 5-15P (| . |) and 5-20P (| . -) plugs the latter being rated for 20A. The UMC has adapters that program it to tell the car how much it may draw. Thus to get the 16A you must have the 5-20P adapter which can be bought separately or one can buy the adapter kit which includes it. The only adapters that come with the UMC itself are the 14-50P and 5-15P. While 1920W may not seem much of an improvement compared to 1440W it is a 33% gain.

So you will have to buy EVSE, be it the UMC which used to come free with the car or a wall "charger" or some other portable solution. This gets us back to what I think the OP really wanted to know: how big should the wiring be? The answer to that is, IMO, as big as you are comfortable with financially. A factor to consider with the Cybertruck relates to its consumption of over 400 Wh/mi relative to the 200 -350 Wh/mi consumption of other BEV. Home charging is done to replace miles consumed in daily use. If I use 100 mi/day in an MX that means I need to replace approximatley 32 kWh each day. In a CT it might be 49. EVSE on a 60A circuit can do that in about 4.25 hr. EVSE on a 30A circuit would take twice as long (8.5 hr). Note that the corresponding times for the MX are 2.8 and 5.6 hrs using, respectively, the 48A from a 60A circuit and the 24A from a 30A circuit.

Most of you should be able to do the math for your own situations based on your anticipated daily use. Obviously having to add more than 100 miles per day in a vehicle that consumes 450 Wh/mi is going to drive you towards the larger wire size (and with it, more cost but do not give much credence to anyone who tells you that 50A is "astronomically" more expensive than 30A). Think about the future too. Will you acquire a 2nd BEV within a year or 2?

 

[ajdelange]

A battery isn't considered cycled until it goes below 50.

That's really good news because the batteries in my Powerwalls never go below 80% and thus never complete a cycle meaning that they will never reach their rated cycle spec and never need to be replaced! But clearly that's not the case. After 10 years they will hold appreciably less charge than they do now and will have to be replaced.

Cycle specs are sort of like EPA miles. They are more for comparison of batteries than for prediction of how long a battery will last.

There are many thing that hasten the demise of a battery the major one of which is loss of lithium. As a lithium ion has a less than 100% probability of completing its journey at either the anode or cathode it should be clear that round trip current would be a major factor in life span. But it is not nearly that simple. We know that temperature, which part of the charge cycle one is in, charge or discharge rate and even rest time have an effects. Current in the very bottom of the SoC range can destroy a cell, for example.

 

[Crissa]

Leaving batteries full also has a form of degradation. Why would you think that not completing a cycle would make it not happen?

• Time erodes batteries.
• Heat erodes batteries - tho only high heat.
• Not balancing cells erodes batteries.
• Time spent at 100%. The further you are from 50%, the more this happens.
• Time spent at 0%. But zero is worse, a couple days at 100% is a tiny amount, leave it at zero and it'll be dead.

-Crissa

 

[SwampNut]

Oh geez, so much misinformation in this thread. A charge cycle is any equivalent usage that adds up to 100%. Here’s the most succinct explanation in Wikipedia from the apple site. Going from 80 to 70% ten times is a cycle.

Apple Inc. clarifies that a charge cycle means using all the battery's capacity, but not necessarily by discharging it from 100% to 0%: "You complete one charge cycle when you’ve used (discharged) an amount that equals 100% of your battery’s capacity — but not necessarily all from one charge. For instance, you might use 75% of your battery’s capacity one day, then recharge it fully overnight. If you use 25% the next day, you will have discharged a total of 100%, and the two days will add up to one charge cycle."

You can also find this, and much more knowledge, on the battery university web site. I’ve spent hours reading. I have a LOT of lithium batteries in my house so I learned to care for them.

 

[Crissa]

Yeah, it varies by manufacturer, there's not a standard.

-Crissa

 

[SwampNut]

It’s the laws of physics, manufacturers don’t get to suspend them. It’s equivalent wear. I’m not referring to how a cycle spec claim is written, just the physics of wear.

 

[ajdelange]

Leaving batteries full also has a form of degradation. Why would you think that not completing a cycle would make it not happen?

I wouldn't. I'm just pointing out that the "cycles" specs given for many batteries does not, by any means, give the complete story. I was trying to make a little joke. You said my Powerwall batteries didn't ever cycle because they never dip below 50% and I was pointing out that they would, therefore, never reach their lifetime spec of X cycles, whatever X may be. I also went on to point out that they nevertheless would eventually expire because of calendar degradation, lithium loss due to fast charging, rest time.....

 

[ajdelange]

Oh geez, so much misinformation in this thread. A charge cycle is any equivalent usage that adds up to 100%. Here’s the most succinct explanation in Wikipedia from the apple site. Going from 80 to 70% ten times is a cycle.

Yes, and now the the bottomless font thereof has just given us some more.

No, a cycle is NOT any equivalent usage then adds up to 100%. A cycle is whatever the standards body that defines what a cycle is says it is. An academic paper reporting on degradation vs cycles will usually specify exactly what their protocol for testing is. For starters, in a battery, "empty" and "full" (the difference between them being 100%) is arbitrary. The standard will define that. I believe IEC has a standard for lithium. It defines a cycle as charge from V1 to V2 using a CCCV charging profile at C/r with a termination current of a ma (don't remember what V1, V2, r or a are) followed by a rest for some time (half an hour?) followed by discharge at constant current, C/R, back to V1.

Apple, Inc clarifies that a charge cycle means using all the battery's capacity, but not necessarily by discharging it from 100% to 0%: "You complete one charge cycle when you’ve used (discharged) an amount that equals 100% of your battery’s capacity — but not necessarily all from one charge. For instance, you might use 75% of your battery’s capacity one day, then recharge it fully overnight. If you use 25% the next day, you will have discharged a total of 100%, and the two days will add up to one charge cycle."

This isn't the definition of a charge cycle at all but rather Apple's attempt to explain to tyros such as yourself the basic concepts of battery operation. It would be extremely inadequate to, for example, compare the degradation of two phones.

Think about it. A battery manufacturer publishes a curve showing capacity vs number of cycles. User A runs 1 MWh of juice through his charging and discharging at 10C. User B runs 1 MWh of juice through his charging and discharging at C/10. According to your definition that's the same number of cycles. Do you think the two batteries will have the same capacity?

 

[ajdelange]

Yeah, it varies by manufacturer, there's not a standard.

Well yes there are standards for example the IEC standard I mentioned in my last post but they aren't often (that I have seen) referred to. For example when Tesla promises the "million mile battery" they don't put in the footnotes that it's that with respect to IEC - xyZ45 Rev.B. This is why, as I also noted, that academics tend to spell out what their protocol was when they publish results on new battery chemistries.

 

[Crissa]

It’s the laws of physics, manufacturers don’t get to suspend them. It’s equivalent wear. I’m not referring to how a cycle spec claim is written, just the physics of wear.

Yeah, and the specs are not physics. They're just rules that we wrote down. The spec you described is just straight watthours output, divided by capacity. But it's not standard to describe cycles that way. It can be any charge-discharge cycle of a certain percentage. Or times it gets to full. Or some mix of things.

(This is why standards are important to codify).

Do you think the two batteries will have the same capacity?

Literally no one has claimed that. It's called a Appeal to Extremes fallacy.

This is why, as I also noted, that academics tend to spell out what their protocol was when they publish results on new battery chemistries.

Or don't, because they're trying to game the system and get more investment for their project, which is why the 'new battery breakthrough' game is so frustrating. Even for academics.

-Crissa

 

[ajdelange]

User A runs 1 MWh of juice through his charging and discharging at 10C. User B runs 1 MWh of juice through his charging and discharging at C/10. According to your definition that's the same number of cycles. Do you think the two batteries will have the same capacity?

Literally no one has claimed that. It's called a Appeal to Extremes fallacy.

Call it what you will. The intelligent individual will respond to the question by saying to himself "Of course not - but those charge/discharge rates are absurd." But he will also understand where the instructor is going and, we hope, ask himself "Well how about 5C and C/5 or 2C and C/2?"

 

[Crissa]

Call it what you will. The intelligent individual will...

...call it a disingenuous argument. Because no one charges modern cars like that. They use sensors to calculate the temperature of the cells as they're charging and constantly change the rate to keep it at the optimal temperature.

It's not linear. Neither is degradation. Stop treating it as such, it's an analog chemical system.

-Crissa

 

[ajdelange]

...call it a disingenuous argument. Because no one charges modern cars like that.

We aren't talking about charging cars. We are talking about the things that effect battery longevity and proposing gedanken experiments to give us insight. I'm afraid we are discoursing on very different planes.

They use sensors to calculate the temperature of the cells as they're charging and constantly change the rate to keep it at the optimal temperature.

Don't know what you are talking about here. In a test protocol the current would be held constant and coolant flow regulated to hold temperature up to the point where the charging profile transitions to CV. The current then naturally declines as SoC increases. More or less the same in the car.

It's not linear. Neither is degradation. Stop treating it as such, it's an analog chemical system.

What does linearity have to do with it? Who said any thing was linear? I can't stop treating it as such because I never began treating it as such. But as a good engineer/analyst I have to say there is a good linear approximation!

I'm not familiar with any digital chemical systems.

Have to take that last statement back. I once had a device sold as a "Digital Titrator". Just a syringe with plunger driven by a screw coupled to a Veeder-Root counter.

 

[Crissa]

What does linearity have to do with it? Who said any thing was linear?

You did:

Think about it. A battery manufacturer publishes a curve showing capacity vs number of cycles. User A runs 1 MWh of juice through his charging and discharging at 10C. User B runs 1 MWh of juice through his charging and discharging at C/10.

"Well how about 5C and C/5 or 2C and C/2?"

So yeah. Did you forget your own argument? Somethingsomething higher charge rates should be more charging cycles because reasons?

No one said all charging cycles were made equally, lest of all ones that are out of spec by double or more.

We aren't talking about charging cars.

We aren't? I'm posting on a truck forum talking about traction batteries in cars.

I guess we're done, then.

-Crissa

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