[bro1999]

OK, armed with some working Torque Pro PIDs, a no-connection fee raping upgraded EVgo membership, and some more moderate temps, I headed to the 125A ABB-made EVgo station near me. Could the 4th time be any better??

Since it was almost 70 today (what the hell happened to winter?), the HV battery was plenty warm (62.6F according to Torque Pro). SOC was 33% according to the station when I started charging.



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Immediately got a 38 kW/100 amp charging rate right after plugging in. It clombed up to around 45 kW/125A over the next 5-7 minutes. Saw a peak rate of 46 kW according to the car.

When SOC hit 53-54%, the Bolt ramped down to 100 amps and a 37-38 kW charge rate, where it stayed till the end of the 30 minute session.

So 33-66% SOC in 30 minutes. 20 kWh in 30 min for a total of $3 (10 cents x 30 min), or 17 cents/kWh.

I plugged in again for the heck of it, and charge rate went right to 38 kW. Staued there till it hit 70% SOC, when it ramped down to 23/24 kW and 60-61 amps. Stayed there through 81% SOC, when I finally pulled the plug after 20 more minutes. Charged 9 more kWh.

 

[Ladogaboy]

The ramp up still seems a bit slow, but the 45 kW rate is fairly consistent with my experiences. Also, my experiences are that the charge rate throttles down to 100 A at 55% SOC, but that is according to the charger. Was the 53-54% SOC reading from the Torque Pro readings?

 

[bro1999]

The ramp up still seems a bit slow, but the 45 kW rate is fairly consistent with my experiences. Also, my experiences are that the charge rate throttles down to 100 A at 55% SOC, but that is according to the charger. Was the 53-54% SOC reading from the Torque Pro readings?

Nope, the station.

Also, I'm wondering how long the Bolt would have held the 23 kW/60A charge rate past 80%. The station said 81% when I pulled the plug.

 

[llninja]

So 33 to 81% in 50 minutes... what did that do to the guessometer in terms of estimated range?

 

[bro1999]

So 33 to 81% in 50 minutes... what did that do to the guessometer in terms of estimated range?

Well, GOM readings would have been misleading, since I drove around for 20 miles with the heat (and defroster) on full blast to try and make sure the battery was running near its optimal temperature (and drain the battery as low as I could).

Basing the miles gained off the battery SOC% and the EPA range would be more accurate. 238 * (.81 - .33) = 114 miles of range gained in 50 minutes. And 33% SOC gained in 30 minutes.

If my charge level had been around 10% instead of 33%, I likely would have observed a “maxed out” charge of ~45 kW nearly the whole time during my first 30 minute session, which would have probably given me the “90 miles in 30 minutes” GM says we can get. I got 78 miles in 30 minutes using the EPA range.

Also, I actually saw the amperage reading spike above 125A briefly (125.X), which suggests the Bolt was limited by the stations 125A max output. I’m really curious what the Bolt can do if hooked up to say a 150-175A DCFC station.

 

[Ziv]

So approximately 45 kW charge rate up til 53%, then 37.5 kW charge rate til 70% and finally 28 kW charge rate from 70 to ?
Are there higher amperage chargers coming to Northern Virginia, Bro? I have almost stopped using chargers, so I am not out there scoping on the charging situation.

My take away on this is that you are really doing us a great service by documenting the charge speed of your Bolt.
And that I wish GM had designed the Bolt so it was easier for you charge faster, if the charger itself is/was capable of it.
Finally, I can't wait for public DCFC chargers to reach Tesla speeds. Heck, even getting beyond 50 kW real world to 75-80 kW real world charge rates might allow you to charge 40 minutes and get 50 kWh/175 miles of additional AER.

To infinity, and beyond!
Buzz

;-)

 

[PH2]

Much better! Chevy seems to be more conservative than necessary with the taper. A taper isn't really necessary on most Lithium chemistries until it passes an SOC of ~70%. Bro, are you happier with these numbers?

 

[Raymondjram]

"Since it was almost 70 today (what the hell happened to winter?)..."

What is "winter"???

Seriously, I never see any cold weather here. We still have "summer", with temperatures passing 80 degress every day. Yesterday it was 86 here, and today we expect even higher. Here is my local temperature:
http://www.accuweather.com/en/pr/bayamon/00961/weather-forecast/272113

With these temperatures, any EV here will get exceptional ranges, probably the highest in the nation.

 

[DonC]

Thanks for taking the time to share all this information. Interesting and helpful.

 

[hvacman]

Bro - great post. Questions:

That Torque Pro is a very handy tool. It looks like the battery temp got up to about 79 degrees F. During the charging session, did you happen to notice if the battery conditioning system pump ever came on to cool the pack, and if so, at what battery temperature did it come on? And if so, was it just the pump or did at some time did the AC compressor also turn on? Can your Torque Pro get that info next time? It would be interesting to figure out what the battery pack thermal window is before active pack heating or cooling is required, and when the AC compressor has to also engage to keep the pack TMS loop cool enough.

 

[Sean Nelson]

Chevy seems to be more conservative than necessary with the taper.

That's the way I'd want it! Considering that most of my charging would be at home, I'm fine with spending some extra time to coddle my battery when I'm on the road.

 

[Henry_FL]

That's the way I'd want it! Considering that most of my charging would be at home, I'm fine with spending some extra time to coddle my battery when I'm on the road.

The 70%+ SOC taper is more likely switching to constant voltage mode, and then would see a gradual decrease in the current draw, standard for how batteries take their charge, its not something the car commands.

 

[jsmay311]

I wonder if that minimum temp of ~70F for pulling the full 125A would be the same even at a lower SOC? Or if temperature-related charge rate limitations also vary with SOC?

Thanks again, Bro, for publishing the data. Very interesting stuff.

 

[Jeff N]

Nope, the station.

Also, I'm wondering how long the Bolt would have held the 23 kW/60A charge rate past 80%. The station said 81% when I pulled the plug.

Not much longer. I did a DC charge starting from about 18% SOC up to 89% and saw essentially identical rampdown transitions on a ChargePoint 125A station. My peak charge power was about 43 kW but I think that is due to the charger not quite proving 125A (someone commenting on the PlugShare entry for that location said it provided them a peak of around 111A as I recall).

I recorded my data minute-by-minute based on station and car readouts but did not have an OBD II reader hooked up. A driver of a new LEAF pulled up and started asking me about how to DC charge and I got distract and missed recording for several minutes but the transition from 23-24 kW to 15-16 kW occurred between 81% and 85% full.

 

[flyingsherpa]

Now you just need a button for "DCFC pre-heat" where it heats the battery to 70F-ish on your way to the DCFC station (assuming you have enough spare capacity to use for heat), to maximize charge rate and minimized time spent at the station. Doubt they'd ever give us that option, oh well...

 

[PH2]

The 70%+ SOC taper is more likely switching to constant voltage mode, and then would see a gradual decrease in the current draw, standard for how batteries take their charge, its not something the car commands.

Exactly, until that constant voltage point a taper isn't usually necessary for lithium batteries. Starting a taper as early as 55-60% likely doesn't do much for the battery, especially since it is charging between .7C and .75C on a '50kW' charger. Ref. BatteryUniversity.com From the snapshots it looks like the min voltage would be somewhere around 340volts; 340V*125A=42.5kW, which would make the ramp-up a little conservative as well.
On CCS the car's EVCC communicates with the SECC to establish operational parameters (i.e. max A, max V, termination current, max charging time, etc.) to work within specs for a car/battery pack as programmed as this varies greatly. Any component of the CCS system should be able to 'command' power rates based on input/programming. Ref ISO 15118.

 

[Ladogaboy]

The ramp down from 25 kW happens somewhere between 85-90% SOC, at which point it throttles to about 16 kW.

Also, bro... what is the function you are using for the HV Bat temperature? Mine won't register using the same functions provided for the Volt PID.