Many recent posts about installing the fastest charger and why this might not be the best approach?

[dbsb3233]

More electric vehicles means lower rates for all rate payers so long as the electric vehicle is paying anything above the marginal cost of generation. This will invariably happen since most of the cost of delivering electricity is in the high embedded fixed costs of transmission and distribution.

To give an example, where I am a kWh might cost $.27. Of that amount $.05 is the cost of generation. So long as electric vehicle owners are paying more than this amount they are contributing to a reduction in the bills of other ratepayers.

In a time of demand destruction for electricity, electric vehicles are about all electrical utilities have going for them. In this regard the big problem for ratepayers is not discounts for electric vehicle charging, that's a positive, it's bypass by large companies.

That's not really true. You can't (fairly) assign all the embedded fixed costs to the TV and the oven and the porch light but not the BEV that's charging in the garage. It all adds to one's total usage, and the fixed costs fairly spread across all usage. Otherwise that game could be played for every product in the home. Does the dryer count, but not the computer? The furnace but not the lamps? The BEV but not the garage door opener? No, it all counts.

Time-of-day could come into play though. Since demand in the late afternoon and evening tend to be highest, electricity tends to cost more to generate then. And less in the middle of the night and morning. At least so far. Widespread BEV charging overnight could shift that around some. But that's a different matter than the fixed costs, that can only fairly be applied to all usage, not selective.

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[2Ponies]

How are you going to get from 20% or so to 90% in the single night before a long trip using an L1 EVSE?

I agree, no way from 20 to 80 on the MME.. I meant I can do it in my Leaf, it only has about 12Kwh capacity left. I will charge the MME overnight and add a few miles, defiantly not going to go from 20 to 80 at 110V. I will probably Keep the MME somewhere between 50% and 80% most of the time. It will not be my commute car yet, so it will have plenty of garage time to slow charge. I plan to drive the leaf into the ground as my daily commuter for a year or two more..

 

[SnBGC]

I agree, no way from 20 to 80 on the MME.. I meant I can do it in my Leaf, it only has about 12Kwh capacity left. I will charge the MME overnight and add a few miles, defiantly not going to go from 20 to 80 at 110V. I will probably Keep the MME somewhere between 50% and 80% most of the time. It will not be my commute car yet, so it will have plenty of garage time to slow charge. I plan to drive the leaf into the ground as my daily commuter for a year or two more..

Does not compute.
You are going to leave the MME parked and drive your Leaf instead?

I like my Focus Electric. It does what I need and has great features but it gets demoted to second string as soon as the MME arrives.
Sorry Focus......love ya.....but I hope you understand.

 

[2Ponies]

Does not compute.
You are going to leave the MME parked and drive your Leaf instead?

I like my Focus Electric. It does what I need and has great features but it gets demoted to second string as soon as the MME arrives.
Sorry Focus......love ya.....but I hope you understand.

I will get to drive it some days, if my wife gives me permission. LOL She just retired and it will be her toy at first, and she will not not putting to many mile on it. Besides, she says I already have a toy with my Shelby.

 

[SnBGC]

I will get to drive it some days, if my wife gives me permission. LOL She just retired and it will be her toy at first, and she will not not putting to many mile on it. Besides, she says I already have a toy with my Shelby.

You are a better husband than me. My wife gets the Focus Electric because her drive to work is only 3 miles each way so the car will be perfect for her. At least that is my story.....

 

[ClaudeMach-E]

I agree, no way from 20 to 80 on the MME.. I meant I can do it in my Leaf, it only has about 12Kwh capacity left. I will charge the MME overnight and add a few miles, defiantly not going to go from 20 to 80 at 110V. I will probably Keep the MME somewhere between 50% and 80% most of the time. It will not be my commute car yet, so it will have plenty of garage time to slow charge. I plan to drive the leaf into the ground as my daily commuter for a year or two more..

Once you'll drive the MME I'm not so sure you'll leave it in the garage.

 

[DBC]

That's not really true. You can't (fairly) assign all the embedded fixed costs to the TV and the oven and the porch light but not the BEV that's charging in the garage. It all adds to one's total usage, and the fixed costs fairly spread across all usage. Otherwise that game could be played for every product in the home. Does the dryer count, but not the computer? The furnace but not the lamps? The BEV but not the garage door opener? No, it all counts.

Time-of-day could come into play though. Since demand in the late afternoon and evening tend to be highest, electricity tends to cost more to generate then. And less in the middle of the night and morning. At least so far. Widespread BEV charging overnight could shift that around some. But that's a different matter than the fixed costs, that can only fairly be applied to all usage, not selective.

No idea what point you are trying to make in your example of a BEV, an oven, a TV, and a garage door opener. None of these represent fixed or embedded costs nor do they involve the assignment of costs.

You do seem to accept dynamic pricing. If demand is high at some times and low at other, raising prices during peak demand and lowering them at times of slack demand equalizes the use throughout the day and cuts costs for everyone. This isn't a subsidy for those who use electricity at the lowest times, it's a means of matching supply and demand.

Once you accept dynamic pricing then it shouldn't be difficult to understand the role of marginal cost pricing. If an airline has empty seats on a plane, then, in order to fill these seats, it should cut prices enough to fill the seats. The only restriction is that the price cover the marginal costs so that the sale of the tickets makes a contribution to the fixed cost of the flight.

Same principle holds with electrical pricing. Since the price of a kWh of electricity is dictated by the price of the last kWh purchased, to reduce peak demand and the concomitant high prices that follow, prices for off-peak electrical usage should be cut to shift demand. The only restriction on the price should be that it cover marginal costs, which is the price of generating the electricity, and that it makes a contribution to the fixed costs of transmission and distribution. Unclear why you think this pricing is unfair to those who use electricity during peak periods since this pricing reduces prices for these customers.

Finally, in CA outright subsidies to owners of electrical vehicles are a means of paying back the electrical customers who have generated carbon credits for the utilities. Electrical utilities accrue carbon credits based on charging electrical vehicles. They can sell those credits, but the PUC requires that they share some portion of the proceeds of those sales with their customers who have played a role in generating the revenue. No idea why you think this is unfair to those customers who aren't generating carbon credits and additional revenue for the utilities.

 

[Rhynri]

One thing I'd worry about from personal experience is that Ford properly handles cold battery temperatures... e.g. they do things like limit the discharge current when the battery is cold. Our Spark doesn't do that as far as I can tell... or I haven't seen it or felt it do that, rather. It'll let you take 120kW out of a cold battery. And that's one tiny battery to be beating up like that.

 

[dbsb3233]

No idea what point you are trying to make in your example of a BEV, an oven, a TV, and a garage door opener

It was illustrating the flaw in how it appeared you were attributing fixed costs (which actually aren't very fixed). Adding 10% to monthly electricity demand by buying a BEV doesn't just mean it can be counted at only the raw electricity generation cost with none of the infrastructure, maintenance, administration, and other "fixed costs" attributed to it. That additional 10% has all those additional costs too. Higher usage can easily mean more equipment, more generation plants, beefier transmission lines and transformers, upgraded service, etc etc (i.e. more "fixed" cost).

A BEV may increase your electricity usage by 10%. Installing air conditioning is the same way. Or a heated pool, or any other large draw. Overhead costs apply to all of it, not just the next item you add. Going from 1000 kWh a month usage to 1100 is still 1100 no matter what products are using it.

Again, that's different than if you're ONLY using electricity for something during a low demand period (and thus cheaper cost). That's an entirely different angle than TOTAL usage. It's true that many BEVs are charged overnight. But as charging stations spread, and workplace chargers spread, that's usually daytime charging. So it really depends on when each BEV is being charged as to whether it's a low cost or high cost time.

 

[dtbaker61]

In the distant past I seem to recall that when you got new rechargeable devices you were supposed to run them close to 0 and recharge full or batteries could take on a memory with lower capacity. Is that not an issue anymore if it was ever an issue at all?

Lithium cells do not develop a capacity 'memory' the way NiCad batteries do.... so, no, the LAST thing you want to do is run Lithium down to zero; in a multi-cell pack, this runs the risk of zapping whatever single cell might be a little shorter on capacity than all the others.

Lithium batteries prefer to be full, (but not overfull).

'Overfull' is what can happen if you charge a cell to 100% capacity when it's warm, and then it cools down. as the Lithium matrix cools and shrinks, it can't hold quite as many electrons. Being forced to release electrons internally rather than moving them out under load does a little damage, and will reduce capacity.... this is why long term storage recommends 50% charge... so cell temps can fluctuate and not damage cells. This is also why cells shouldn't be charged when < 32F or so (unless there is internal enviro control of the cell temp inside the packs like all good OEM battery packs have now). That enviro heat/cooling DOES self-consume some energy from the pack to keep the cell temps as close to 70 deg F as possible, which is optimal for Li cells.

'Over Temp' issues are caused by either overcharging (if the BMS/charger/regen fails to cutoff at proper upper voltage), or if you drive under maximum load continuously for too long (the minimal internal resistance causes internal heat, and more current = more heat, and the enviro system may not be able to keep up). This is why in race situations BOTH the motors and batteries may need supplemental cooling.

 

[dtbaker61]

One thing I'd worry about from personal experience is that Ford properly handles cold battery temperatures... e.g. they do things like limit the discharge current when the battery is cold. Our Spark doesn't do that as far as I can tell... or I haven't seen it or felt it do that, rather. It'll let you take 120kW out of a cold battery. And that's one tiny battery to be beating up like that.

high loads on a cold battery won't hurt it (not like Alkaline where cold vastly increases the internal resistance and voltage sag from Peukert's Law for Lead-acid).... in fact it's 'good' for Li as high loads will warm the battery up a little internally, which the sensors should regonize makes a little more room to charge or store regen energy.

 

[dtbaker61]

This may indeed work for you, but not for everyone. My TOU rate kicks in @ 8:00 PM, but in the summer I would prefer to start charging @ midnight. ...

If your TOU rates kick in at 8pm, why wouldn't you start charging at 8:15pm?

 

[Rhynri]

high loads on a cold battery won't hurt it (not like Alkaline where cold vastly increases the internal resistance and voltage sag from Peukert's Law for Lead-acid).... in fact it's 'good' for Li as high loads will warm the battery up a little internally, which the sensors should regonize makes a little more room to charge or store regen energy.

That's interesting, I didn't know that. Thanks! Since Tesla limits the amount of acceleration on a cold battery, I assumed it was for battery longevity.

Edit: Clarity

 

[shutterbug]

If your TOU rates kick in at 8pm, why wouldn't you start charging at 8:15pm?

Because summers in Arizona (Phoenix) are HOT. So I would want to wait until it's below a 100°.

 

[dtbaker61]

That's interesting, I didn't know that. Thanks! Since Tesla limits the amount of acceleration on a cold battery, I assumed it was for battery longevity.

I don't know the exact internals of the Tesla BMS/control system, but would guess that the current draw is limited on cold batteries for two reasons. One is cold Li voltage 'sags' a little under heavy loads, which means even MORE current is required for the same kW output. Most likely is is current limiting kicking in rather than simply because of temperature.

i.e. if pack is cold, and you call for max amps of current... you get less power output because voltage is a little lower than it would be at 70 deg F

This is why if you want maximum output from a cold pack... it's actually GOOD to do a couple 'acceleration events' under moderate/heavy load to warm up the cells.

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