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Discussion Starter #1
As has been discussed, more businesses are installing KeyWatt brand semi-fast DC chargers - nominal 24 kW, 65A. I typically see 21-22 kW while using one (that figure from its display, not the car dash)

Yesterday I used one around 9PM (after dark) Ambient temp about 90*F. My initial SOC was 13%; final SOC 30%. Charge rate started at 21 kW and then tailed off to 18 kW, where it remained until I left.

I'm curious as to why that lower charger rate occurred...ideas, anyone?
 

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Don't have an answer, but a question or two. How long was the session? What was the total kWh transferred? Where was the charger installed?

I ask because I believe these medium speed DCFC deployments are going to be the backbone of the local public charging infrastructure in the future. They are at the nexus of speed, cost, usability, and flexibility that will serve both as opportunity charges, like the one you describe, or as primary charges for folks who may not have steady at home charging access. I'm really interested in understanding how useful the stations in that 20 kW charging speed ballpark are in situations such as stopping at the grocery, or picking up a quick charge in an apartment complex.

TIA for any answers,

ga2500ev
 

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I see from your other post that this is a Harley Davidson charger. 3 or 4 of them have popped up here in the metro Atlanta area. Mixed reviews both on availability and on accessibility including one hair raising post on Plugshare where the owner apparently threatened to call the police on a Bolt owner that needed a charge.

It looks like one thing HD shops may need to look into is charging money for charging and discounting the price to free for electric HD motorcycle owners. Adding a price typically takes charging from an opportunity to a need only usage.

ga2500ev
 

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Discussion Starter #4
I've used a half dozen or so of the medium speed chargers, and occasionally mull what it would take to install one at home.

Specifics of the particular session: 39 minutes, 12.40 kWh added at Harley Davidson dealer Baymeadows, Jax FL. Gotta love ChargePoint statistic records!

The one's I've used are KeyWatts at 2 BMW locations, the HD one cited earlier, and a Chevy Dealer's Bosch / Delta unit in Gainesville.

I'm not sure where these fit in to the future of public charging infrastructure - The vast majority of EV charging is now at home...most of the rest being rapid charging while on long road trips where speed is paramount.

Another segment is destination charging - L2s in hotels and at workplaces where hours of parking time are available.

If a charger owner / operator threatens to call the fuzz, fine...whatever. Leave and warn others on Plugshare...also leave a 1 star review on Google and wherever else one writes online reviews

Ga2500ev - interesting point - some thoughts on medium L3s:

1) May well form an optimal middle ground for EV adoption by folks unable to have L2 at home - renters, apartment dwellers, homes with inadequate electric service etc

2) These add useful amounts of charge during longer errand - type stops - grocery shopping, public libraries, big box stores. Obtaining 30-40 miles of range during a 30 minute shopping stop provides right at what the average daily driver needs.

Getting, say, 3 kWh / 12 miles of range from an L2 station during a 30 minute errand stop would generally be not worth the hassle unless one's car is very very low on charge.

3) Installation cost much less than faster stations - KeyWatt and Bosch have variants that run on single phase 208 / 240V circuit. Installed cost $20-30k maybe?

4) Less impact on host electric bills, though impact on demand billing must always considered.

5) Free isn't sustainable - should be supported by per-kWh (where allowed) or similar per minute rates. Might be attractive / conducive to EV adoption at cost per kWh no more than twice the at-home rate...much higher than that might ward off the budget-conscious. 6 to 10 cents per minute might be in range.

There are probably synergies available attractive to retailers - knowing one's car needs a bit more charge could encourage shoppers to linger - ALWAYS a good thing for retailers. Imagine also affinity card synergies - swipe to start charging at a lower cost using store credit card or membership card - get charging credits in exchange for shopping. Local retailers already have shop-for-cheaper gas deals...in the case of EVs, the retailer gets to "sell the fuel" without tanks and gas pumps and all that entails.

6) Battery degradation - many of us worry, to varying degrees, about accelerated battery degradation stemming from very fast charging. Medium speed L3s would seem to balance that concern against getting a useful amount of charge while shopping.

7) Medium L3s could represent a niche not now well served - Electrify America and EVGo are plowing millions into very expensive, complex high speed chargers. That's great - we need them for road trips. However, the cost and complexity of siting them probably means we won't ever have anywhere near many of them as we now have gas stations.

8) I'm less sure how well medium speed L3s would work for apartment complexes - their managers around here more often than not let dead couches and mattresses pile up for months at a time, never mind splashing out $20-30k to put in a charger...that said, the bigger problem would seem to be getting people to move cars after an hour or so after arrival.

L2s would probably make more sense for apartments - overnight charging in the parking spots nearest where electricity enters each building might be easiest to install.

Medium L3s might eventually make sense in low-end apartment complexes whose units lack washer dryer hookups - tenants spend 30-60 minutes at the central laundry building. If multiple electric dryers are installed, there's likely a fairly heavy duty electric service in place...For this to be worthwhile, EVs will have to have trickled down to the income demographic that uses central laundry buildings / laundromats...that could be a ways off.
 

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Outstanding post! Do you mind if I quote it in the future?

For apartment dwellers it's #2 and #3 that are the focus. Installation is going to be less than $20k. The units are running from $8-12k retail. And as you pointed out it's installable with the 208-240V infrastructure that's already in place.

The combo that makes it attractive for situations such as apartments are the costs and the flexibility. The problem with L2 is as you pointed out inflexible in terms of time. So what ends up happening is a much larger scale deployment of L2 to have nearly 1-1 service between L2 EVSEs and EVs. A single medium speed DCFC, especially with longer range EVs such as the Bolt, can gain significant range in limited time. For your example of 18 kWh in an hour, which is 72 miles at an average 4 mi/kWh, then someone can get 150 miles of charge in just a couple of hours and be set for a couple of days of local driving. So a medium speed DCFC could be shared among several EVs instead of trying to get a 1-1 match for overnight charging. The second item is always flexibility. There are times when folks only have an hour. Getting 60-70 miles of range in that hour is so much more useful than getting 20-25 miles using L2. BTW I don't think the laundry is as critical because the whole point of having a station on site in an apartment complex is that one can simply go home for the hour or two while charging the car, which is where the resident was likely going to be anyway.

In the end it'll probably end up being a mix of the two. But I feel that multi unit spaces having a significant or all parking spaces electrified with L2 really isn't going to work.

If the public charging infrastructure could expand to have just one medium speed DCFC unit in every parking lot, it would go a long long way to solving the public charging infrastructure problem in a much more cost effective manner than ultra high speed charging stations and much more flexible that the L2s we see in a lot of places now. So I'm real interested in seeing how this Harley Davidson experiment works out. As I said in my other posts, there are now 3 or 4 nearby medium speed stations to me because of HD.

ga2500ev
 

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Discussion Starter #7
Oh and I think I might have found the answer to my original question - why'd I get only 18 kW?

I downloaded a pdf product info sheet from Ies-Synergy - manufacturer of KeyWatts. They are listed to function at up to 50*C (122*F) but derate themselves above 35*C (95*F).

Turns out I was off a bit on what time I started the charge session - it was before 8 PM, sun was still out, and it had been a very hot day. I do remember noting how warm the unit was to the touch. My educated guess is that the unit reduced current supplied to my car owing to high temperature.
 

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Discussion Starter #10
The Bosch spec of 165 amps seems based on an absolute worst case scenario - 25,000 Watts at 187 volts (the absolute minimum tolerable voltage for a dual rated 208-230 load) divided by 0.80.

A 125-150 Amp circuit would likely suffice at typical home split phase voltage of 230-240.
 

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Discussion Starter #11
Yesterday I hit up the local Harley Davidson Keywatt again for about 40 minutes around dark. Once again it started at 21.5-ish, inched up to 22 kW, and then ramped down to 18-19. The unit's fan is quite loud while in operation, and the side panels with air louvers run too hot to touch - I can only imagine what that means for the elctronics within...

I'm looking forward to comparing results at other KeyWatt 25 kWs in future, and as the weather (finally) cools.
 

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Wow, timely post! I charged at a DCFC at our local HD dealer last night and also noticed the phrase “medium fast” on the center console. Fasted I got was 21 kW.
 
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