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TickTock
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Contact: Website

Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 10:19 am

Interesting. So it takes however much current a particular delta_V results in (probably with a max I limit).

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JeremyW
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 10:59 am

garygid wrote:Since the Chademo vehicle expects the input current (thus power) to follow
its requested current, and there "appears" to be no provision for providing
substantially less (or more) than requested by the car, or abort the charging
session.

True, there is a negotiation (kind of a mating ritual) at the beginning of the session,
before any charging actually starts, and part of that is the QC machine saying how
much voltage and current it can supply, and then the car wanting a demonstration
of the voltage "dance" from the QC machine. If the ritual is satisfactory (to both
sides), charging begins with a relatively fast, but controlled (by the car) ramp up
of the charging current, done at the present battery voltage, of course.
The charger sends out the maximum current avalible every 100ms (along with its other parameters). I haven't seen any that dynamically adjust during a session though. It should be possible.

The car requests the charger do an insulation test by having the charger ramp to 500v while looking for leakage current with the contactor to the battery open. After no leakage current is detected (and the charger goes to 0v), the car closes the contactor and the charger ramps up.
Former 2012 SL leasee 6/23/12 - 9/23/15
Former Fit EV leasee.
Now driving Spark EV and Model 3.

LEAFfan
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 11:46 am

KillaWhat wrote:
picked up on an earlier comment indicating the car requests a particular voltage but thought that was strange. I would have though the car would request a particular current (and just have a max voltage safety setting)
I have just started looking at the DCQC, so If I'm off here , my apologies.
I have watched my meter system while the Car was QC'ing, and it seems to me that it "pivots" around the Max KW output of the charger.

As the Voltage of the charging pack increases, the current output decreases accordingly.
I take it that this is why it takes almost no time to get to 80%, but it has been noted that QC'ing beyond that is not time effective.


That's not accurate for the 2013's. I can QC to 90% in 30mins. or less.

So I assume that the system is adjusting the output VOLTAGE to remain above the pack voltage, but not drastically so.
2013 LEAF SV Del. 2/28/13
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klapauzius
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 1:02 pm

Are you planning to build a DC source from scratch or are you going to use an off-the-shelf component?

This is very exciting! I think it would great if the system could take AC input e.g. from a regular J1772 EVSE .

KillaWhat
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 1:49 pm

I take it that this is why it takes almost no time to get to 80%, but it has been noted that QC'ing beyond that is not time effective.


That's not accurate for the 2013's. I can QC to 90% in 30mins. or less.
I don't know everything about how the DCQC is controlled. YET

The level 2 is completely controlled by the system onboard the vehicle.
I have built some custom L2 EVSE, and I can tell you, there is NO intelligence in there.
It's a glorified Light switch with the ability to abort if some criteria occur.

The L3 charging on the other hand seems to be controlled by the external charger, with the car reporting some data that the Chademo can use to make adjustments.

I doubt that the 2013 has any significant changes in the DC charging system that would affect it's operation over the 2012 design.

I have a pretty nice metering system, and can watch the car's internal data as it charges.
The only DCQC I have access to is a Blink Chademo, and it will not offer me the option to go beyond 80%.
(anybody know what that is about?)

My car can charge from 25% to what the charger thinks is 80% in 14 minutes.
The initial current is very high, but at 13 minutes it is down to 25% of what it was when I initiated the charge.

I'm not holding you to the 30 minute estimate number, but lets assume for now that it's accurate.
That would mean that it took as long to go from 25% to 80% as it would to go from 80% to 90%.

This is in keeping with that tapering as voltage increases I noted, even if the times are not set in stone.

Just a note: The Blink I have access to stops my charge at 72% (by meter) even though it thinks its 80% (showing on the Blink)
I'm interested to see if that changes when I get the update done.
Black SL Delivered 3/14/2012
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TickTock
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 3:06 pm

garygid wrote: We intend to deliver our work into the public domain, and we
request that our collaborators endorse this same philosophy.
Sweet! :D [thumbs up]
garygid wrote: The Robomo Project breaks down into several sub-projects:

1. Understanding the QC interface, handshake signals, and CAN communication.
2. Construction of a plug that is sufficiently pin-compatible with the LEAF's QC socket.
3. Obtaining or building a suitable, controllable DC power supply.
4. Doing some very careful, well-controlled experiments.
Sounds like there are several different types of power supplies folks would like to use. Perhaps a key element of the Robomo Project should be:
2.5. Develop a QC controller with parameterized code and a generic power supply interface that can be bolted onto any power supply meeting the minimum requirements.

I think there is a lot of value in having such a component that could be common to everyone exploring this space and it seems to be in keeping with the spirit of the project you set out.
We could

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JeremyW
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 4:39 pm

KillaWhat wrote:The L3 charging on the other hand seems to be controlled by the external charger, with the car reporting some data that the Chademo can use to make adjustments.

I doubt that the 2013 has any significant changes in the DC charging system that would affect it's operation over the 2012 design
To be clear, the charger is controlled by the car over a CAN link. The charger is dumb the car is smart. ;)

The 2013's are better at estimating time remaining and SOC, and send these bits of info to the quick charger. The blink is only reporting what it gets from the car. For once it's not blink's fault! :lol: I also hope the update addresses this, although I'm not exactly holding my breath.

You can select "100%" by going into other settings (or other selections, cant remember the name at the moment) when presented with the 70 and 80% options.
Former 2012 SL leasee 6/23/12 - 9/23/15
Former Fit EV leasee.
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kubel
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 5:07 pm

I don't have QC on my LEAF, but I really like the intent of this project. I have nothing to bring to the table of any practical use, except free cPanel/apache/php/mysql web hosting on a VPS if desired. Feel free to PM me and I'll hand over keys to an account. Otherwise, I'm just looking forward to seeing what comes out of this.
2012 Nissan LEAF SV
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Leased 5-17-2012, Returned 1-15-2016


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garygid
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 5:16 pm

Ten times per second the car sends, among other things, the
current value that it expects the QC to provide.

When the battery gets fuller, the car starts requesting less current.
When the car requests zero (0) current, the charging session ends normally.
Other than error conditions, it is up to the car to decide upon the charging
profile, and to determine when to end the charging session.
Of course, the user can push the STOP button at any time.

We have posted a CAN-Do compatible log of the QC-CAN bus during
a QC session, which was ended by the car at 80% SOC, as I recall.
In the log, one can follow the commands from the car to the
QC device, and the responses.

The QC device really has no idea how big or how full the car's battery is,
or what type of battery chemistry is involved, or even what type of car it is.

The car does send a "progress" type value to the QC machine,
but it is not yet clear to us just how this number should be scaled, or
what it is supposed to represent. It appears that the QC machine
usually uses this value to display some kind of progress indicator.
See SOC/GID-Meter and CAN-Do Info
2010 Prius
2011 LEAF, 2014 Tesla S85
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garygid
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Re: Mini-DC charger Project for QC Port

Sat Jun 22, 2013 5:50 pm

To get started we bought a battery charger kit that should be
able to charge at about 10 kW. The charger was designed to
charge a dumb battery pack, using a pre-specified constant
current up to a certain voltage, then maintain the constant voltage
as the current decreases, and then (at some point), quit charging.

It is about one cubic foot, and air cooled. However, it will
just be used for testing the interface and protocol, and be
replaced by another design later.

We are are working on substituting a different controller, that
can control the charger differently (as needed for a QC session), and
is able to do the 4 handshakes and the QC-CAN bus communication
with the LEAF.

The first version of this Robomo controller will likely be run from an
isolated power supply that can be grounded to the car's "ground"
(usually the chassis) and be optically isolated from the charger itself.
See SOC/GID-Meter and CAN-Do Info
2010 Prius
2011 LEAF, 2014 Tesla S85
2018 & 2019 Tesla Model 3
PU: SDG&E
Solar PV: 33 x 225W -> 7 kW max AC
Craigslist: Xm5000Li Electric Motorcycle

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