Why do public DC chargers not deliver rated KW?

[MM in SouthTX]

Looking at that area on Plugshare, it looks like you're pretty limited. If EA can't get Snappy's Market working reliably, I guess your only hope is Tesla opening up their network. But I'll believe that when I see it.

Yeah, I was staying 20 miles north of Columbus. I even left it at the Ford dealer next to Snappy’s for a day on their slow charger. That’s how I managed to get to Houston.

One day soon…but not yet around here. Thanks for the help.

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[davehu]

".... Going on the road is still quite complicated. Wife’s car with ICE for the road. Problem solved. Until we get a reliable network down here.

that's my plan. trying to plan a trip from Hot Springs, AR to Houston is very iffy. just not enough stations if your off the freeway which is they way we like to travel. My wife's Honda Pilot gets 28mph and will be our trip car for at least 2-3 years.

 

[hturnerfamily]

what I've found in 6,000 miles, and many stops at DC Fast Chargers, both when traveling, and WHEN TOWING... most any power unit delivers a lot 'less' than advertised, at least what we might 'assume' as the power output that we will be delivered.
I believe most of it is advertising the 'max' output the station can potentially provide, not that it actually WILL. Some of it has to do with the vehicle, yes, but I highly doubt that my last stop at the Chargepoint in Dothan AL, downtown, hosted by Dothan Utilities, was only providing 24kw because of my 'truck'... I surmise that it is the charge unit, whether not operational as it should be, or whether the owner, the utility, has actually 'derated' it's output.
I've never seen a 125kw 'shared' Chargepoint have an output of more than 70, no matter whether anyone else is there, or not.

We're in the 'infancy' stages of the national charging infrastructure. There is no government 'minimum standards' for this. There is no 'rhyme or reason' why many don't work as advertised. We 'might' see some standardization in the near future, at least let's hope.

and, this is not just us, Ford owners, it's everyone... well, except Tesla owners. Oh well.

 

[2wheeltraveler]

In Kerrville, TX we had a similar issue, 50kw charger only providing 29kw. We were towing out to Lost Maples and needed a full charge and the higher speed charger at the nearby James Avery has been offline since Feb leaving this our only option. It took 2 hours and 44 mins to go from 24 - 90%. Better than it could have been, but not ideal and it's unfrotunately validating my wife's fears of roadtripping in the Lightning.

I called charge point to report it and they said that the charger was capable of 50kw, but it was configured to run at a lower rate by "the owner"

 

[Calvin H-C]

With six years of driving a Focus Electric under my belt and having to use DCFCs on some road trips, including some relatively short ones due to the 100 mile range of the FFE, I've picked up on a few things.

As others have mentioned, the environment (mainly ambient temperature and if the vehicle has had some time to heat up or cool) and the SOC of the battery will dictate the maximum rate it can receive. That doesn't mean the charger will deliver that, even if it's rating is that or greater.

The rating on a DCFC really only means it's hardware (especially the cord and connector) is rated for up to that level.

A little math will tell you the power feed is not likely to provide what the units are rated for, possibly even if only one is in use. Many sites have banks of batteries so they can continuously charge at the rate their supply can handle, but have a stored supply available to feed to vehicles at higher rates when needed. Add to this, the site may limit what it draws from its supply when rates are higher.

This will limit what the station can deliver in total and showing up a little after others have reduced the stored supply will further limit what the station can deliver. Think of taking a shower just after several others have done so (and you have a tank water heater) - you will find your shower rather cold.

The fastest my FFE has ever taken a charge was 53 kW and it will sustain that rate up to about 88% SOC before beginning to ramp down, getting to about 20 kW by 95%. Given similar conditions, 48 kW is a more common maximum, if the site can deliver it.

I once stopped at an Electrify Canada site with no other cars charging and it ramped up quickly to about 48 kW. Then a Polaris 2 arrived and started charging and my DCFC dropped to 29 kW. I took a look at the DCFC for the Polaris and it was delivering 129 kW. That suggests that the location may have only been able to deliver 150 kW in total at that time, though given that my car could only take 49 kW, the other could still get 100. I would have to spend twice the time to get the charge I needed and because EC charges by the minute (most still do in Canada, though the rules recently changed to permit kWh fees), I would be paying double for that same charge. It occurred to me that EC's fee structure has a higher per minute fee above 125 kW, so perhaps their system prioritizes vehicles that can charge above that.

Saturday night, we were in the Buffalo area and I topped up my wife's Lightning using a ChargePoint DCFC rated at 62.5 kW. Given the conditions, the truck could take more, but the best the unit could do was 53 kW. It was free to use, so I can't complain.

I would be curious to know what the vehicle is saying it can take, either something on the dash display, or through some plug adapter that can eavesdrop on the communications. One charging network here in Canada, Flo, seems to regularly deliver less than what the vehicle can take given the conditions, in my experience. About a year or so ago, they changed the message sequence on their chargers to show what the vehicle is requesting, but I don't believe it. I consistently will have other chargers (EC, EA, ChargePoint, Shell Recharge, and Petro Canada to name a few) deliver 45-48 kW in similar conditions where a Flo charger will only deliver 37-39 (40 if I'm really lucky).

 

[biers]

TIL that Ford lets the FFE DC charge significantly faster from 80-88% than the Lightning with 3-4x the batter.

Even if we could have 60-75kw from 80-90% that would make the truck better for road trips.

 

[Yellow Buddy]

I have had my Lightning less than a week, and all I have at home is 120V charging so far. I took a trip around south central Texas, including Houston, and found that every station I went to delivered far less energy than advertised. For instance:

EA station in Columbus, the two 350 KW stations delivered 36 and 43 KW. The 150KW station delivered 135 for a short while then stopped, like 4 times.

EA stations on 59 south of Houston (Stafford, Sugarland) were not working.

EVgo at Cracker Barrel on I-10, 50KW station delivered 25KW.

EVgo at Whole Foods on 59 50KW station delivered about 44KW.

Here in Corpus Christi the two Charge Point stations are 62KW but deliver 27KW.

Am I doing something wrong, or is this a common experience? I should have the house set up to charge soon, but road trips are definitely not in the near future around here.

It doesn’t have to be hot out for the stations to throw a fault. A lot of the EA stations can throw a fault due to high usage, which causes them to overheat. They can even throw a fault due to power supply issues and the entire set gets limited.

It’s not likely to be an issue with your truck but an issue with the station.

As for the rated vs actual, it’s due to voltage differences. The chargers are rated in KW but the reality is they deal with Volts and Amps.

Our trucks are pegged to a hard voltage based on battery architecture. So we’re voltage limited, only the amperage varies. I don’t remember the exact numbers but some stations are limited to 300A for example but rated to 150KW meaning they’re 500V capable. But 400V * 300A = 120KW max in that situation. But if another truck uses a 500V architecture it would be able to fully utilize the 150kW output.

Edit: Should note our maxed voltage is pegged, didn’t mean to imply we can only charge at a set voltage.

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