JoeS
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Joined: Thu Dec 15, 2011 5:47 am
Location: Silicon Valley, California

Re: ChargePoint Charging Question

Sun Jun 02, 2019 7:05 pm

kevin1956murray wrote:"... and the highest 800 µs giving 48 A).[22]"
Interesting, as I've drawn as much as 70A from J1772 with my dual-charger Tesla S85. For example, I got close to that in Iraan TX https://www.plugshare.com/location/19815
kevin1956murray wrote:I have a theory that when a MiEV pauses, the Chargepoint software assumes that the car is done, and modifies the pulse widths of both cord's pilot signals so that more current can be supplied to the other cord, if a new session were to start on that other cord.
Agree with you, and that is almost exactly the question I posed to my ChargePoint acquaintance. Let's see what he comes back with. :geek:
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

JoeS
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Posts: 3762
Joined: Thu Dec 15, 2011 5:47 am
Location: Silicon Valley, California

Re: ChargePoint Charging Question

Sun Jun 02, 2019 11:22 pm

Burrowing down further into the details, on the January 2019 ChargePoint plot (February 2, 2019 post), is it safe to assume that the jump from 1.1kW to 3kW occurred when the car using the adjacent port unplugged? Fair to say that did something which allowed the i-MiEV charger to go back to full power draw?
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

kevin1956murray
Posts: 47
Joined: Sat Jan 19, 2019 1:29 pm

Re: ChargePoint Charging Question

Mon Jun 03, 2019 2:56 am

Looking back at that, I would say that it is very likely that the other car unplugging might have caused the station to adjust (and refresh) pilot signals, and that is what likely caused the charge going back to 3kW. Too bad that station has such low usage, otherwise others plugging out could often be my workaround to get away from the funky 1.1kw slow rate.

kevin1956murray
Posts: 47
Joined: Sat Jan 19, 2019 1:29 pm

Re: ChargePoint Charging Question

Mon Jun 03, 2019 6:12 am

Thanks to Joe S's digging into details, and the new theory that a neighboring car unplugging from a shared station might cause a MiEV charging to move from the funky 1.1 kW "post pause" rate back to 3 kW, it occurs to me that I might be able to replicate that in a controlled fashion.

I have the 2012 MiEV and a 2011 Volt, so I can use the Volt as the 'neighboring' car. So soon I intend to catch a time when the MiEV is down at 1.1kW, and go see if I can affect that rate by plugging the Volt in and out on the other cord, without touching the MiEV cord.

I plan to leave the Volt plugged in at least 10 minutes, since the 'trace' read points are only every 5 minutes (after the initial ramping up).

Hopefully the neighboring car does not need to be drawing more than 3kW, since that is all that the Volt will take.

JoeS
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Location: Silicon Valley, California

Re: ChargePoint Charging Question

Mon Jun 03, 2019 7:10 am

Kevin: check your Private Messages - I sent you a PM asking for the latest ChargePoint ticket number. Thanks.
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

kevin1956murray
Posts: 47
Joined: Sat Jan 19, 2019 1:29 pm

Re: ChargePoint Charging Question

Mon Jun 03, 2019 11:07 am

Today a drove a little extra, to discharge the battery enough where for sure it would pause during charging, and I plugged in at a dual cord Chargepoint station. I had planned to plug in my other car once the MiEV had paused and dropped to 1.1kW, but it turns out the other cord was put in use before I had a chance to do that. So then the experiment changed to just monitoring if the MiEV rate would go up when the "Find Stations" screen showed that the other cord was available.

So I monitored that, and oddly, my charging rate went back to 3kW a few minutes before that cord showed as available. (I intend to attach screenshots below). It is possible that that car had then fully charged, and then 5 minutes later the owner unplugged it. Or it could be there is a several minute delay on station availability updates, compared to charge rate data updates.

Anyway, the increase back to 3kW appears to be definitely related to the other cord changing from charging to not being needed.

I think when that happens, the Chargepoint dual cord stations adjust the pulse widths of the pilot signals, likely in a attempt to get more charge to the active vehicle. So when the MiEV pauses it charging, the station kind of gives up on it, and indicates to the MiEV that it will only give it 1.1kW. It will hold that way until the session physically reinitialized, or the station is rebooted, or until a car using the other cord stops needing a charge.

I plan to suggest to Chargepoint that they make the stations reanalyze each cord more often, since at 1.1kW the station should be able to sense that that car still wants to charge, and maybe could pull more than 1.1kW if the pilot signal were to allow it.

12:31PM when power came back: Both cords show still "in use":
Image

12:37PM after another 'every 5 minute' read point: Other cord shows as available:
Image

ChrisEV
Posts: 83
Joined: Tue Nov 14, 2017 3:47 pm
Location: GTA, Canada

Re: ChargePoint Charging Question

Mon Jun 03, 2019 11:38 am

I'm in Canada but my 2012 i-MIEV doesn't have this problem and I have tried many chargepoint units around the city. Is there a specific ChargePoint model# this happens at?

But my car has done the timeout many times at a ChargePoint station, it usually happens If I arrive with 20% or less, it will timeout at around 36%, ChargePoint will actually terminate the session remotely now if it goes on too long, about the time that the car pauses charging. Even though the CP app says the session ended my car resumes charging.

If it's only dual-chargers it may be that the voltage is too low, all the public chargers I've tried my car pulls 208V/14A. I've seen the voltage as low as 205V and the current is 14.1A at most if I recall.

I've seen comments on PlugShare in the area that the Leaf refuses to charge at some public stations that drop below 200V but I was able to use them no problem.

Just some ideas.
2012 i-MIEV SE Premium

kevin1956murray
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Joined: Sat Jan 19, 2019 1:29 pm

Re: ChargePoint Charging Question

Mon Jun 03, 2019 11:47 am

I do not know any Chargepoint station model numbers, but on all four dual cord Chargepoint stations that I have tried, all four very dependably change to just 1.1kW after the pause. The single cord Chargepoint stations dependably return directly to 3kW.

ChrisEV
Posts: 83
Joined: Tue Nov 14, 2017 3:47 pm
Location: GTA, Canada

Re: ChargePoint Charging Question

Mon Jun 03, 2019 1:33 pm

kevin1956murray wrote:I do not know any Chargepoint station model numbers, but on all four dual cord Chargepoint stations that I have tried, all four very dependably change to just 1.1kW after the pause. The single cord Chargepoint stations dependably return directly to 3kW.


These are the shared power stations correct? There's stations that will share 6.6kW of power between 2 cars and ones that will provide 6.6kW max to 2 cars plugged in.

I've used both, I don't think I've had the pause happen on the shared power variant now that I think about it.
2012 i-MIEV SE Premium

JoeS
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Location: Silicon Valley, California

Re: ChargePoint Charging Question

Wed Jun 05, 2019 9:19 am

OK, so here's where we stand. In a few email exchanges with this acquaintance, he, on his own and not part of any official ChargePoint response, preferred to take the empirical approach and first measure what the pilot is telling the car and how the car is responding. Evidently, there have been significant issues with other manufacturers (i.e., cars not complying with the J1772 spec) that this is the logical first step.

To that end, what I intend to do is, when running low on charge, seek out a dual ChargePoint station and plug in and monitor the charge (using the ChargePoint app) to see when I get a 'timeout' and what the response is after the 'timeout' goes away. If I can make the problem occur then I will contact my friend and we can get together so he can attach his instrument and we can measure the pilot and car's power draw. He's really interested in seeing what the EVSE pilot signal is commanding in our situation. Even though we're convinced it's the EVSE, this test will conclusively prove or disprove this supposition. Come to think of it, I'll ask him if they have a dual-port EVSE at ChargePoint's HQ as I can drive down there to do this test.

The hint by ChrisEV that the timeout occurs at 36% is a great clue, as I had previously never been able to understand when this occurs.

Independently of that, kevin1956murray, perhaps send an email to ChargePoint's customer service and simply ask for a status on that last open 'ticket' you have?

Now, during my email exchanges my friend said that if anyone is interested in measuring an EVSE pilot then here's a relatively-inexpensive kit to do that:
https://www.tindie.com/products/nsayer/evse-tester/
The issue I see is having to make a J1772 breakout cable to be able to tap into the signal while using the EVSE without actually opening up the box to do that.

'Nuff for now, as I'll be driving over 150 miles in my i-MiEV today and need to do my EVSE availability homework...
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

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