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Mini-QC Rapid-Charger (RC) Project for LEAF QC Port

Posted: Fri Jun 21, 2013 7:23 am
by garygid
The general goal, that many have speculated about, is having a "small",
portable, not-too-heavy, 240v (standard split phase), not-too-expensive
DC charger for Rapid-charging our QC-equipped LEAF vehicles.

In Public places, 240v 50 amp service is not uncommon, like at
RV parks, and not difficult to have at home. With the higher-power
service available at some homes, 240v at 100 amps is obtainable,

Thus, 12 to 24 kW of input power is generally available, so we
hope to be able to dump 10 to 20 kW into a QC compatible port.

Thus, the Robomo Project took shape, and is making progress.

If you have experience that would help, want to participate or
just offer suggestions, we encourage you to let us know.
It is better to post any questions of general interest, so
that the posted answers can benefit all readers.

We intend to deliver our work into the public domain, and we
request that our collaborators endorse this same philosophy.


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.

Current Status of each area:

1. We think that we have a basic understanding sufficient for very
controlled laboratory experiments. An AVR-CAN board is being
programmed to control a DC power supply, and communicate
with the vehicle's QC port.

2. A plastic handle and pin-holder has been 3D printed, but
I am struggling with getting the pins made. Not difficult,
but I have been a bit dizzy recently.

Later, it would be nice to get the insert-ends silver plated.
Who knows a good way to do this?

3. We have a DC power supply that we expect to use for
some carefully designed feasibility experiments.

However, in designing our own experimental power
supply circuits, experience with toroidal transformer
design and winding would be useful.

4. The first experiments are broken into several types:

A. Controlling the Power Supply, both when un-loaded,
and when delivering power (just modest power to start).
AnAVR-CAN board is being programmed to interface
with the power supply, and regulate its output
voltage and current.

B. Communicating well with the Vehicle.
An isolated module to control the 4 handshake signals
and the CAN communication is being constructed
and programmed, at this point based on the AVR-CAN
development board that I use in the GID-Meter.

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:24 am
by garygid
A Plug for the QC Port:

Goals:
1. Short term, get something to safely hold and align
the pins (2 big for power, 7 small for handshake) to
allow us to begin experiments involving the vehicle.

2. Long term, provide a method by which interested
folks can obtain a very inexpensive cable-end connector,
for their own experimental usage. No, not UL listed.

Progress:
First, reasonably accurate dimensions were needed,
and I think that we are doing well in that respect, at least
sufficiently well to make something that fits the LEAF's
QC port socket.

A 3D model was attempted on SketchUp, but it appears that
the free version is primarily suited for modeling shells,
or entirely solid objects. Maybe there is a way to model
internal voids within the solid, but I am not an expert in
using SketchUp, so I might be missing something.
However, a derived STL file could be used to drive
a 3D printer, I believe, with the appropriate settings
in the "slicer" for external walls and internal filler.

Another 3D model was made using Binder (?) and used to
print a 4-section 3D-Printed "plug" which will be sufficient
to hold the pins for our first experiments. No, it does not
yet have the latch and interlock, but that is being worked on.

Printed in PLA plastic, in a nearby country. :D

The handle is in two halves, connecting to a pin-retainer plate,
which attaches to the rear of the plug (pin holder part) that
mates with the QC socket.

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:26 am
by garygid
The pins for the plug

A. The two 9mm diameter Power Pins

These are the easiest to make, using a small lathe, since
the material is sufficiently rigid to allow easy machining.

For our initial experiments, we are using stock 1/2 inch
diameter copper alloy rod, 2-3/4" long, with a hole drilled
about a half inch into one end to receive the power wire.

The pin is one piece, with a 3/8" diameter body, leaving
a 1/4" wide, 1/2" diameter retaining collar, and a just-shy
9mm mating-pin part, about 1-1/8" long, with about 1mm
of 45° taper at the tip. The "body" extends 3/4" from the
collar to the wire end, and 5/8" from the collar toward the
very smooth 9mm mating section of the pin.

B. The seven 1/16 inch diameter Signal Pins

Here, the mating part of the pin is about 5/8" long, and
only 1/16" diameter, so not strong enough in brass to
machine, at least by me. So, I plan to make the pin
in 3 sections, a body, a collar soldered onto the body,
and the mating part, soldered into a hole in the body.

So, I bought some 3/16" diameter stock brass rod for the
body of the pin, and 1/16" diameter brass rod for the
mating section. A 1/16" diameter hole drilled in one end
of the 2-1/8" long body will receive the 1/16" diameter rod
to form the 5/8" long mating part of the pin, resulting
again in a 2-3/4" long pin.

A hole drilled in the other end of the body, about 1/16"
diameter and 1/4" long, will provide for soldering in
the signal wire.

Then, some "thick" wall brass tubing, with
3/16" ID and 4/16" (1/4") OD can be cut into 1/4" long sections
to slide over the body and get soldered in place to form the collar,
again located 3/4" from the wire-attachment end of the body.

For me, cutting the tubing nicely and squaring up the
walls to form a nice collar is still problematic.

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:27 am
by garygid
Communicating with the vehicle's QC port

There are 4 handshake signals, a Ground, and two CAN
bus lines, in addition to the two big power pins.

We have observed the 4 handshake signals, and they
seem to match what is described in open literature.

etc...

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:27 am
by garygid
Controlling the Power Supply

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:28 am
by garygid
Power Supply design

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:30 am
by garygid
Experiments:

Future:

Planned:

Under Construction:

In Progress:

Done:

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:30 am
by garygid
Miscellaneous FAQ:

1. Are you planning on selling this or will it be an Open Platform?

We intend to deliver our work into the public domain, and we
request that our collaborators endorse this same philosophy.

There are no specific plans to produce a UL listed product,
or even sell all the parts for a kit.

We are primarily interested in helping to provide the supporting
knowledge to everyone, and making one for our own (non-UL) use.

We are carefully staying away from reading, obtaining, or using
any proprietary documents. We are observing what is there.

So, OpenRobomo, perhaps?
Is that "Power to the People"? :o

2.

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:31 am
by garygid
Miscellaneous #2

Re: Mini-DC charger Project for QC Port

Posted: Fri Jun 21, 2013 7:31 am
by TickTock
Nice! I'd like to participate. In my case, I have a 384-536V unregulated, 12kW *DC* source available (i.e. solar). What are you using to regulate? Can it take DC in if it is sufficiently above the "ask" voltage. I can do 12kW at 384V but the power tapers down above that so maybe I can only get to 80% without having the overhead of a high power DC-DC converter.

[Edit: Oops, sorry - didn't mean to steal the Misc. #3 slot)