Thinking on completely draining the HV Battery Pack. Thoughts?

[Timeless Epoch]

Ok guys, a quick and dumb question or maybe a dumb and quick question. Anyway I had lunch at a Hilton Garden Inn yesterday. Found out afterwards they had level 2 chargers out in back. Went out to look at the charger and NACS handle. The station digital display read "16.64 KW AC MAX".

This has me wondering with the AC to DC conversion plus this 10% cell balance crud, what would be the effective battery KWH charge that would be added to my battery per hour from this charger assuming let's say for sake of argument, a battery level well under 80%?

I'm assuming the max rate would go down from 16.64 AC as it went over 80% and other levels as it got close to 100%. It would also use the Stellar style adapter plug. Thanks.

Your truck maxes out at 11.5KW gross in for level 2 charging.

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[RickLightning]

A whole bunch of misunderstanding here...

Level 2 chargers are either NACS or J1772. With NACS, you could use a Stellar adapter.

There is no "10٪ cell balance crud". You lose ~10% in loss between wall and vehicle,so 16.64 would be around 15kW. But you max at 48amps, so 10.5kW or so.

There is no slowing down at 80% with level 2. It slows down at 99%, and THEN may do cell balancing, staying at 99% for as much as 45 min or an hour.

 

[bc1]

Clear as mud so far. My guess at a recap from above not including plug style. Truck (2025 Flash with extended battery) internal charger maxes out at 11.5 kwh per hour on level II so no matter what any external charging source is, the max I can get is 11.5 KW per hour. With an approximate 10% loss through the power cord, I would only get 10.5 KW in an hour of charging assuming 48 amps. However, I see nothing in my actual knowledge as to anything about charging at 48 amps. I don't know what amp rate they are using or how they are arriving at 16.64 which is part of my question I'm hoping someone may or may not need to know to compute the final answer. I did not get a brand of charger except the serial number of each charging station starts with BAE if that is a clue. Sorry. Thanks.

 

[Timeless Epoch]

Sounds like you are pretty clear. Yes, your truck maxes at 48A at 240v, or 11.5KWh (at the evse).

How they are arriving at 16.64KW? One would assume they have an 80A charger that is throttled to around 70A, probably due to the circuit it is on.

 

[RickLightning]

Or, they have less than 240v.

240 x 80 = 19.2kW
207 x 80 = 16.6kW.... Ding, ding, ding.

But that's irrelevant due to your max.

207 x 48 x 93% = 9.24kW would be what you will likely get, because the amperage is the restricting factor (48amps), and the lower voltage is what will drive your total.

IANAE (I Am Not An Electrician)

Truck (2025 Flash with extended battery) internal charger maxes out at 11.5 kwh per hour on level II so no matter what any external AC Powered charging source is, the max I can get is 11.5 KW per hour.

The internal charger has no impact on DC level charging.

 

[TaxmanHog]

I'm assuming the max rate would go down from 16.64 AC as it went over 80% and other levels as it got close to 100%

At peak flow up to 97+% it should net 10.4 kWh on a 240 volt circuit to the HVB after approx 10% conversion loss AC/DC, then the last 3% of charging during balancing phae, it's a crap shoot as to the gross energy consumed to achieve 100% top off.

-edit-

As Rick points out the high likelihood that 3 phase energy at the hotel is limiting you to gross energy of 9.936kWh [48 amps x 207v}net to the HVB will be ~90% of this value or 8.942 kWh.

 

[bc1]

OK. Thank you very much guys. 9 to 10 KWH is expected in an hour then. This is a brand new just opened last October Hilton so I'm sure they designed 3 phase into it and not some ad hoc add on circuit at an old hotel. Next time I'm down there I'll stop by and charge for an hour just to see what it does give me.

Guess I wasn't thinking about the charging amps but then I probably wouldn't have been thinking about 3 phase either. After watching all variations of charging rates, I've lost track especially now that I plug in at home or else use a supercharger for 30-40 minutes.

So bottom line on a level 2 hotel charger should be 9-10 kwh per hour if the battery is under 80%. An overnight stay should bring one up to 90% at least.

 

[chl]

Please don't take this personally (as you're only referring to what's said in the reports).

While the general conclusion still stands (that it's better to have smaller / lower ammounts of discharge) the "facts" and the effects are a bit of an apples vs. oranges comparison here considering that they're talking about charge cycles and not throughput.
I mean, if you use 40% instead of 80% you'll charge twice as often, so in reality your battery will not last 2.5 times "longer".

It is also not an apples to apples comparison in that they charge the battery / cell to 100% in the 80% discharge cycle vs. say 30-70% in the 40% cycle and we know that charging to 100% is "bad" so how much of that loss is due to charging to a high SoC and how much is due to the depth of discharge ?
No-one changes their charge levels based on their anticipated use the next day or two, we all charge to 70-80-90% or whatever our default setting happens to be, so it would be more interesting to see a 80%-20% vs. 80%-40% vs. 80%-60% and then take overall throughput in mind. Is charging (i.e. ABC) 65%-80% every day better than 35%-80% every three days. Now add to that equation the effects of the battery sitting at higher SoC levels for more / longer time...

I suppose my point is that I don't think synthetic / lab tests tells the whole truth about charging behaviours and the longevity of our batteries, doing real life use-case tests would take years vs. weeks / months for the synthetic ones and I'm not aware of anyone that's actually spent that time (and money) to get those kind of results.

In the end I find this quite interesting, but I'm definitely not losing sleep over it.
I don't follow ABC (not so much by choice as by convenience), instead I charge when I need to, usually around 20-40% SoC and I charge to 80%, either way I'm pretty sure the truck will outlive me.

As a sidenote, have anyone in the EV world encountered a "battery diagnostics test" as a part of the tradein / appraisal process ? I mean, if you have a curb rash on your wheel you get money taken off your trade, but if the thing lived on a L3 charger to 100% all its life v.s. pampered / ABC L2 60-80% preconditioned, etc. But I suppose no-one cares about that kind of "invisible" wear/tear.

I get your points, this was apparently a lab study, but I think it helps explain why other real-world studies/surveys of EVs show their batteries lasting longer than originally predicted.

My main point is that I would not intentionally take my SOC to extremes unless absolutely needed, to a high level for a planned trip the next day for example. And with our type of battery, it is not apparently necessary for cell balancing as I understand it, or recommended by Ford.

Real world usage data shows EV batteries lasting longer than the labs tests would expect, and in the real world most of us EV owners do not go up to or above 95% or down to 12% or below like they might do in a lab.

I suppose my point is that I don't think synthetic / lab tests tells the whole truth about charging behaviours and the longevity of our batteries, doing real life use-case tests would take years vs. weeks / months for the synthetic ones and I'm not aware of anyone that's actually spent that time (and money) to get those kind of results.

I believe the study's results are consistent with real world use surveys done on EVs that I have seen in the past.

And this is probably why:

"It is believed that depth of discharge contributes to battery health is because batteries are more chemically stable near the middle of their state of charge. They are less likely to experience physical or chemical stresses near 50% than when they are charged all the way to 95% or discharged down to 12%."

I just cited that one study relating to depth of charge/discharge in lab tests it appears, but I believer there have been others that were based on actual EV's.

It is one reason why the anticipated EV battery recycling they expected did not occur at the rate they first thought.

Virtually all Nissan Leafs and early Teslas were lasting far longer that the companies expected.

That said...

Frequent fast DC charging is probably the biggest factor reducing battery longevity. The higher the power the shorter the battery lifespan due to greater stress on the battery.

Temperature is also a major factor, which is why active cooling is important in hot climates to mitigate that problem.

The length of time a battery sits at an extreme SOC (95% or above, or 20% and below) is another big factor.

And how often it is taken to those levels.
That is directly tied to the number of cycles and throughput.

I'm sure it is a combination of factors.

So I guess my main point is that I would not intentionally take my SOC to extremes unless absolutely necessary.

And with our type of battery, that is not necessary for cell balancing as I understand it, or recommended by Ford.

 

[chl]

Just saw this interesting study of over 22,700 EVs and battery longevity:


How long do electric car batteries last? The updated guide to real-world EV battery health
Analysis of over 22,700 electric vehicles, covering 21 different vehicle models, confirms that overall, modern EV batteries are robust and built to last beyond a typical vehicle’s service life.


https://www.geotab.com/blog/ev-battery-health/

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