Odd experience with DCFC

[JJMcCoySeattle]

Hi All

Partner and I tried a trip from Seattle to near Mt. Vernon in the Leaf yesterday, which necessitated a quick charge at the Aerovironment station in Burlington for the 60 mi trip home. I have to say, the range anxiety was not fun, and they need to put in more quick chargers at closer intervals before I'll attempt that again. We also have a Volt, and as much as I'd like to do trips like this completely gas free, the stress and the extra time involved with taking the Leaf out of town are just not worth it for me.

But I'm curious to get the group's feedback on 2 things. When charging for the way home:

1) the GOM changed its usual behavior, and its range estimates suddenly got a lot more conservative. (More realistic, but why the change?). The GOM has apparently reverted to its usual inflated estimates this morning after recharging on the L2. But it made for extra uncertainty on whether we had the range to get home. Anyone else experience this? Is it something to do with the DCFC? Did we maybe damage something?

Also,

2) The DCFC shut off a whole bar short of full. For comparison, after unplugging the DCFC I plugged into the adjacent L2, and the Leaf said it needed another 50 minutes to get to full, which we weren't so willing to wait for. Is there any way to get closer to full? Battery temp was fine.

The net result of not having that last bar and worrying about the range estimate was that we had to make an unscheduled stop at a L2 just north of Seattle for enough of a margin of safety to let me know we weren't going to turtle on I-5. Luckily, we were able to grab an ok dinner on foot near the charger, but we didn't know the area at all and it made for a much longer day than I had hoped.

Thoughts?

 

[davewill]

If you start below 50%, the LEAF itself stops the charge at 80%. That doesn't quite fit with your description of "one bar short" of full, it should have been two. That said, the charge rate has to slow as the battery approaches full whether on DC or L2, so staying on the DCFC all the way to 100% probably wouldn't have saved much, if any, time over switching to L2, that's why the car estimated 50 min just for that last bar. In fact, moving down the road and using up some battery before charging further likely saved you time overall because the L2 would have charged at full speed at that battery level.

 

[LEAFfan]

Actually, QC to 100% is quicker than topping off with L2. If you are below half on the QC screen, and choose '100%' on the QC screen, it will at times give you more than 80% such as you experienced. So to get 12 bars, override the 80% timer (if set) and charge again with the 100% setting. Since you were at 11 bars, it may only take about 15 more minutes. If your first charge stops at nine or ten bars, then it may take another 30 minutes. I found it's best and quickest to always choose '100%' if you need a fuller charge.

 

[JJMcCoySeattle]

Actually, these Aeronvironment QCs don't offer any choices like 80% or 100%.

The sequence was that the car cut off charging at 80%, and then I re-started (after changing the charging timer to accept 100%). The QC was reading out 93% at that point and climbed slowly. I'm assuming that the QC thought it reached 100% before the car did, which would be consistent with what others are telling me about the discrepancy between SOC estimates between the QC and the car.

I suppose I could have tried re-starting again to see if it would pump a bit more. That appears to have been my only choice. But I didn't want to force things.

In general, I'm realizing that the "quick" charge experience is really only valid for the first 80%, and after that the slowdown in charge rate for the remaining 20% is substantial.

Makes me think the State of Washington has missed the mark (for the Nissan Leaf, at least) configuring these "green highway" stations 60 miles apart. If that's the case then 73 mi EPA range * .8 * .9 (for heater, terrain and traffic contingencies) = around 52 miles is the widest that these things should ever be spaced apart.

 

[DaveinOlyWA]

They did not miss the mark. Ecotality did. They were supposed to install QCs from Olympia to Everett. The AVs were to fill the gaps. It should havr only been 25-30 miles to next QC but blink is a "bit" behind schedule.

Also, it is not faster to continue and fast charge past about 85% or so. So if someone ia waiting to use it the right thjng to do is let them and finish on L2

 

[JJMcCoySeattle]

That's not entirely surprising given how slow Blink / Ecotality / McKinstry was in completing my home charger. Hate to bitch about a free charger, but it's annoying when you have to prompt them for each step in their elaborate process, because nothing moves on its own.

Has anyone done a good blog / post run-down of the current state of play with the Washington program? I see Oregon is going forward with a lot more stations, but Washington seems to be falling behind.

I've used two of the 3 Blink locations in Seattle, and at each, I've had problems with at least one of the two plugs not working. At the Fred Meyers at Lake City way yesterday, the touch pad didn't work (so even if the plug was functional, you couldn't get at it). The Aeronvironment system inspired more confidence.

 

[DaveinOlyWA]

I will say I am more than a bit disappointed at the lack of public support for charging stations which is where OR shines. For the ones that do like Walgreens, I now go out of my way to patronize them. (I have a Rite Aide less than a mile from my home, but will drive an additional 2 miles to the Walgreens instead (although it doesnt have a charging station, its not the point) for any drug store needs.

I will say Fred Meyer in several locations in the Seattle area had wanted to put in QC's from Blink but changed their mind due to high costs of site development. guessing they simply did not have the power available or something. kinda strange for a store that large but...

 

[doug401]

I also charged up at the Aeroviroment QC at Burlington yesterday coming back from Anacortes. Although the anxiety you spoke of is familiar, it also is satisfying to overcome range challenges. Seattle to Burlington is a nice challenge in the Winter. A part of you should feel like you've climbed the mountain, been there... done that. All you need now is a QC in Everett and the whole discussion is mute.

I realized recently that I can QC and run my heater at the same time. But... from 3 bars to 10 bars took 50 minutes. Always trade offs. Also... you may have noticed the difference from the Leaf's state of charge, and what the DCQC chargers are telling you. Usually about a +10% difference shown on the DCQC. This is important to know when going the distance.

 

[kovalb]

1) the GOM changed its usual behavior, and its range estimates suddenly got a lot more conservative. (More realistic, but why the change?). The GOM has apparently reverted to its usual inflated estimates this morning after recharging on the L2. Is it something to do with the DCFC? Did we maybe damage something?

2) The DCFC shut off a whole bar short of full.

1) The range can only be estimated based on your previous driving. I am guessing you drive on surface streets at relatively low speeds for some distance before getting home. When stopping to do the quick charge you probably were fresh off the freeway. This would explain your experience. Low speeds = longer range, high speeds = shorter range.

2) The quick chargers measure SOC themselves and often read different from the vehicle. The last time I charged with a ECOtality DC-FC it did actually match the reading on my LEAF, which is not usually the case.

 

[DaveinOlyWA]

i havent done the stretch you did but did do 55 miles from Seattle to Oly and made it with plenty to spare. I simply drove 55. it took me a few extra minutes. better than sitting at the QC an extra 30 minutes to get a fuller charge. for me? its a compromise but not a big one to me. wear a coat, hat, gloves. some people bring blankets. I have a few in the car but dont like them when I am driving. I am not a cold sensitive person for the most part so I was ok and no, i did not get "run over" driving 55

last week, I had 3 70+ mile trips. my GID count runs 260-265 so if you want to get there, there is a way.

 

[Computerizer]

I've used the DCQC in Burlington twice. The first time I was at probably 60% when I started, and it put me all the way up to 99% (took an hour). The next time I was down to probably 25%, and it cut me off at 83% (took about half an hour). Both times it was about 34 degrees out and I started with 4 temp bars.

I didn't really notice a range change, but I didn't take the freeway -- I was taking back roads to keep my speed down.

 

[planet4ever]

2) The quick chargers measure SOC themselves and often read different from the vehicle.

Really? Different numbers we do know about, but how in the world could the QC measure SOC? The closest I can think of is a guess based on what voltage the battery controller is requesting. I guess it's possible they could get closer by measuring current at that voltage.

Ray

 

[brettcgb]

If you start below 50%, the LEAF itself stops the charge at 80%. That doesn't quite fit with your description of "one bar short" of full, it should have been two. That said, the charge rate has to slow as the battery approaches full whether on DC or L2, so staying on the DCFC all the way to 100% probably wouldn't have saved much, if any, time over switching to L2, that's why the car estimated 50 min just for that last bar. In fact, moving down the road and using up some battery before charging further likely saved you time overall because the L2 would have charged at full speed at that battery level.

In Nov 2012, I had to stop and do a DCFC to get back home. Being bored and a bit curious, I decided to record the elapsed times to reach 5% SOC steps. I started from about 38% SOC and had selected 100%, but the charger stopped at 90%. No matter.

L3 charging speed
SOC step - time (m:ss)
40 to 45 - 1:31
45 to 50 - 1:01
50 to 55 - 1:19
55 to 60 - 1:42
60 to 65 - 1:45
65 to 70 - 1:42
70 to 75 - 1:57
75 to 80 - 2:30
80 to 85 - 3:08
85 to 90 - 4:05

I crunched the data to make the following discovery. Charging when above 75% SOC slows quite a bit. The time to add 5% SOC in the 62% SOC range was 1:42.

I then compared Blinks records of my charging at home. I wasn't looking for a lot of accuracy, so I wasn't considering things like power that the EVSE draws to function. It seems that L2 charging draws 3.6kW (240V) right up to when the charge stops at 100% - the L2 charging power does not taper off as the L3 seems to do. (I expected the L3 to taper off, and thought the L2 might do the same.)

Not exactly an "apples to apples" comparison, but close enough.

 

[DaveinOlyWA]

2) The quick chargers measure SOC themselves and often read different from the vehicle.

Really? Different numbers we do know about, but how in the world could the QC measure SOC? The closest I can think of is a guess based on what voltage the battery controller is requesting. I guess it's possible they could get closer by measuring current at that voltage.

Ray

guessing there is a safety factor built in to prevent accidental overcharging

 

[brettcgb]

2) The quick chargers measure SOC themselves and often read different from the vehicle.

Really? Different numbers we do know about, but how in the world could the QC measure SOC? The closest I can think of is a guess based on what voltage the battery controller is requesting. I guess it's possible they could get closer by measuring current at that voltage.
Ray

guessing there is a safety factor built in to prevent accidental overcharging

The QC doesn't know anything about the battery's SOC - that is communicated to the QC by the vehicles on-board charger. The QC may display SOC as a numerical percentage ( xx% ). The vehicles GOM reports SOC as a low resolution bargraph, and may be following rules which dictate which bars to turn on depending on the SOC (like your cell phone signal strength "bars").

The On-board charger always monitors battery activity (and SOC) and controls the charging process. When charging from the QC, the on-board charger tells the QC how much power to deliver and when to stop. At such high charge rates, it's difficult to precisely know when to end the charge, and Li Ion batteries DO NOT TOLERATE OVERCHARING, not even a little bit. (Stories of aircraft and laptop batteries venting and flaming during overcharge come to mind.)

Better to be safe than sorry by ending the QC early.

 

[LEAFfan]

Brett, it is a whole different story QCing a 2013. First of all, whatever you set it to that is what you will get. The Blink QC matches the car's % exactly. It doesn't stop at 80% if you choose a different % even if you're below 50% and it will charge to 89-90% in a little less than 30 minutes unless it is hot out. Then, 2-3 minutes longer.

 

[KillaWhat]

For the ones that do like Wallgreens, I now go out of my way to patronize them. (I have a Rite Aide less than a mile from my home, but will drive an additional 2 miles to the Wallgreens instead (although it doesnt have a charging station, its not the point) for any drug store needs.

I drive almost 10 miles out of my way to go to Wallgreens, and we have the CVS evil empire here.
(you know... If you stand at one CVS, and look hard in both directions, you can probably find the Next 2 CVS's in the "Chain". In someplaces you don't need to look hard :roll: )

There is a nice sandwich shop 2 doors down.
I plan my trips around lunch.
I break even on the charge, but I'll patronize that Wallgreens.
I drop a couple hundred a month in there, and a $.09 per Kw around here I'm not hurting their bottom line.

We just finally got a Costco, and I was sure they were going to put an L2 in there... But they didn't.
Back to BJ's wholesale I guess.