User avatar
garygid
Gold Member
Posts: 12466
Joined: Wed Apr 21, 2010 8:10 am
Delivery Date: 29 Mar 2011
Leaf Number: 000855
Location: Laguna Hills, Orange Co, CA

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 7:43 am

We need to get you set up for EV-CAN and CAR-CAN logging,
along with GPS data, all simultaneously logged into your PC.

That should greatly simplify your data gathering, and
allow yourself and others to explore and analyze the data.

Other than a Windows PC to run CAN-Do, you need:
1. A USB connected GPS "hockey puck"
2. An OBD cable with custom connector(s)
3. A 2-channel CAN logging interface system
4. A USB connection to the PC for the logging data

#3 and #4 can be done in several different ways,
and I am working on improvements.

I have supplied LEAF Logging Systems to several
groups of investigators. If interested, please ask
for details.
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

edatoakrun
Posts: 5222
Joined: Thu Nov 11, 2010 9:33 am
Delivery Date: 15 May 2011
Leaf Number: 2184
Location: Shasta County, North California

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 7:46 am

I begin every days driving with ~2000 ft total descent in the first 7 miles.

When I start off with a charge of no more than ~90%, regen does almost all of the required braking.

Interestingly, this is true Summer or Winter, as the increased friction of denser cold air very closely offsets the lower regen capability of a cold battery (4 bars on this drive for the first time this yesterday).

When I begin at higher SOC, I find opening all the windows on this part of my trip increases drag enough to spare my discs a lot of wear.

This is a lot less comfortable in the Winter than in Summer, of course.

I'm sure that throwing a small drag chute out of a window, and then pulling it bag in when I reach the Millville plain at ~500 ft., would increase my brake pad life significantly...
no condition is permanent

User avatar
TonyWilliams
Posts: 10091
Joined: Sat Feb 19, 2011 1:48 am
Location: San Diego
Contact: Website

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 11:02 am

garygid wrote: I have supplied LEAF Logging Systems to several
groups of investigators. If interested, please ask
for details.
Ok, let's talk about this at the next OC meet this Saturday. I need a better timing method... maybe lap timers like we use in racing.

I tried 3 runs this morning (keep in mind, climbing 600 feet over and over KILLS that poor battery... I can only do it maybe 8 times max), but on the third run, a friendly Sheriff's Deputy showed up to watch what was going on. So, I only got two runs:

Code: Select all

Sign#        Run1           Run 2
           Time-MPH        Time-MPH
 2           0 - 0            0 - 0
14     0:52.6 - 81      0:51.9 - 81
16     1:38.5 - ..      1:37.8 - 33
Peak GPS  125.9kmh         126.4kmh
My trial runs today were with the Michelin MXM4 tires, size 215-45-17, 36 psi. Stock LEAF (3350lbs / 1350kg) plus payload of me (220lbs / 100kg) and equipment (66lbs / 30kg) and the wheel / tire combination weigh more than the stock Ecopia tires (18lbs / 8kg).

Mass: 3654lbs / 1657.4kg
Relative Air Density: 96.68%
Wind light and variable (below 3 knots)

METAR KMYF 1453Z 11004KT 10SM SCT026 13/09 A3003

Elevation: 1100 feet - 335.28 meters
Air Temperature: 55.4F - 13C
Altimeter Setting: 30.03 inches - 1017 mbar (hPa) - 14.75 lb/in2 (psi)
Dew Point: 48F - 9C
Density Altitude: 1148 feet - 350 meters
Absolute Pressure: 28.856 inches Hg - 977.18 hPa - 14.1728 lb/in2 (psi)
Air Density: 0.0739 lb/ft3 - 1.184 kg/m3

User avatar
TonyWilliams
Posts: 10091
Joined: Sat Feb 19, 2011 1:48 am
Location: San Diego
Contact: Website

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 11:22 am

Boomer23 wrote:Is the "daughter in back seat" condition reproducible? :D
She was the timer.

DaveinOlyWA
Posts: 14470
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 11:49 am

TonyWilliams wrote:
Boomer23 wrote:Is the "daughter in back seat" condition reproducible? :D
She was the timer.
She is my hero! not only has she become invaluable in your quest to reveal the true meaning of the LEAF, she also puts up with you so we dont have too!!

;)
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 3500.3 mi, 96.95% SOH
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

tbleakne
Gold Member
Posts: 987
Joined: Wed Jul 28, 2010 12:05 pm
Delivery Date: 03 Jun 2011
Leaf Number: 2400
Location: Claremont, CA

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 1:14 pm

Herm wrote:If we had an accurate way to measure energy going in-out* of the battery you could find out how efficient regen is.

*that was a hint for Enginier.. a module with a good coulomb counter in it.
I too would like to see regen data from these great tests. Hopefully we won't have to wait for Ingineer.

The Gid meter already reports dynamic battery voltage that can be logged. Just like voltage drop (relative to OpenCircuitVoltage) is a direct measure of battery loss during discharge, the voltage shift up during regen should be a good measure of battery loss during charge. I agree we need either dynamic kW or current logged to plot how the loss varies with regen. Since this is dynamic data, perhaps garygid already has identified its tags.

Of course there are significant losses in the inverter and motor that would be in addition to the battery loss. If you do pairs of downhill runs in both Neutral vs Eco we can derive the total mechanical energy going into the regen system from the velocity profiles, which you are already deriving from your waypoint times. The difference between the mechanical and electrical measurements should be the regen efficiency.

My more crude measurements indicate I am getting overall regen efficiencies in the range 75-79%.

Abasile, who has a lot of downhill experience, has reported that the regen limit can cut back over time scales of fractions of a minute, and it can decline almost to zero as you approach 80% SOC. I have confirmed this latter effect on my recent trip to Idyllwild. Just like QC power tapers down as SOC rises, tracking the increase in battery charging impedance, it seems likely that battery regen losses will increase with SOC. All of this might complicate getting reproducible data.
LEAF Ocean Blue SL, "100 % Electric" decals, Delivered June 3, 2011
Sold June 2014 27K miles, 18% capacity loss, 1 bar, 5.0 mi/kWh.
Solar 4.6 KW DC with both string and micro-inverters.

User avatar
TonyWilliams
Posts: 10091
Joined: Sat Feb 19, 2011 1:48 am
Location: San Diego
Contact: Website

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 3:33 pm

Run 3 and 4, with 50 psi (vice 36 psi) in the Michelin MXM4 tires, plus about 60 pounds for a passenger. Air temperature is up to 68F / 20C, which should favor going faster.

The speeds and times were nearly the same.

User avatar
garygid
Gold Member
Posts: 12466
Joined: Wed Apr 21, 2010 8:10 am
Delivery Date: 29 Mar 2011
Leaf Number: 000855
Location: Laguna Hills, Orange Co, CA

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 4:45 pm

With the simple single-channel logging that the GID-Meter does,
logging the EV-CAN bus messages, we have frequent Pack
Voltage and Current, and times down to (probably) a few
milliseconds. That gives us Power, and ultimately, Energy.
True, we do not know how good the Current measurement is,
but the voltage has Ben verified, I believe.

We also get RPM (related by tire diameter to
speed), but I have not yet identified a trip meter,
which might be in the CAR-CAN data.

Adding GPS logging at the same time, one gets some
often useful information, about once per second.

If someone wants to play with the 3-bus plus GPS data,
I can post a log file of an 18 minute test drive.

There are even some GPS receiver devices that provide
data 10 times per second, up from the more usual
once per second.
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

tbleakne
Gold Member
Posts: 987
Joined: Wed Jul 28, 2010 12:05 pm
Delivery Date: 03 Jun 2011
Leaf Number: 2400
Location: Claremont, CA

Re: Rolling and Aerodynamic Drag Test Track

Wed Oct 24, 2012 5:18 pm

garygid wrote:With the simple single-channel logging that the GID-Meter does,
logging the EV-CAN bus messages, we have frequent Pack
Voltage and Current, and times down to (probably) a few
milliseconds. That gives us Power, and ultimately, Energy.
True, we do not know how good the Current measurement is,
but the voltage has been verified, I believe.
This is very good. I am sure the current measurement is plenty fine for our purposes. When I suggested some time ago adding some integration functionality for those of us without a data-logging Windows laptop, I seem to recall that was not practical because the software environment of your meter's processor did not provide a decent time-base with interrupt delays, etc. Is that still true ? In data-logger mode you have the time in your lap-top and even more accurate time from your GPS dongle.

Maybe some day data-logging to my iPad ?
LEAF Ocean Blue SL, "100 % Electric" decals, Delivered June 3, 2011
Sold June 2014 27K miles, 18% capacity loss, 1 bar, 5.0 mi/kWh.
Solar 4.6 KW DC with both string and micro-inverters.

Return to “Engineering”