mdh
Posts: 122
Joined: Tue Aug 02, 2011 3:09 pm
Delivery Date: 10 Aug 2011

Re: Better (reverse) SOC meter already in the car?

Mon Jan 02, 2012 12:31 pm

surfingslovak wrote:
TonyWilliams wrote:
evnow wrote:Actually the "gids" are not linear - at least near the top (and most probably near the bottom). I had a thread about it sometime back. That probably reflects the difficulty in getting a good measure of SOC near the top & bottom.
Agreed, it's not linear. My statement is the Gid data is perfect (for me) for an SOC meter. Just a teeny, tiny amount of math is needed on the top and the bottom to make it linear.
+1

I continue to gather data, and I'm quite impressed with the accuracy this method provides when trying to predict the remaining available energy, especially at a low state of charge. It's very good, but you are correct, the reverse SOC can in the best case be only be as accurate as a gid-o-meter would be.
I think I need a tutorial for dummies on how to best use this method. Can you make one :)?

tks

User avatar
surfingslovak
Vendor
Posts: 3809
Joined: Mon Jun 13, 2011 1:35 pm

Re: Better (reverse) SOC meter already in the car?

Thu Jan 12, 2012 10:33 pm

mdh wrote:I think I need a tutorial for dummies on how to best use this method. Can you make one?
Matt, happy belated New Year! This took a lot more effort than I anticipated, but here are my preliminary results.

The abbreviated version of my spreadsheet I linked to below is based on a dozen of battery cycles and about 500 individual odometer and energy economy readings. The majority of the cycles were 80% charges, but I went to 100% several times as well. Although I had to push the limits on occasion, I solemnly swear that no Leafs were harmed during the testing!

I'm happy to report that this approach is both practical and reasonably accurate, although it does take some work. But then, what doesn't? The data I've gathered indicates that one hour on the 120V charging display corresponds to 840 Wh on average. This value can go up and down, and I have seen lower figures especially when charging to 80%.

Turtle mode kicks in at 25 hours on a 100% charge and at 21 hours on a 80% charge. The very low battery warning comes one hour earlier, and there appears to be about 1 kWh of usable energy in the battery at that point. Low battery warning is generated at 21 and 17 hours respectively.

These readouts are quite consistent, and they can be used to determine the SOC nearly as well as Gary's meter, albeit with less granularity. As lukati and 91040 determined earlier in the thread, each hour corresponds to about 11.6 gids.

Please keep in mind that the mapping to battery bars is not quite finished, and it was only included as a point of reference. The tutorial is coming, I promise.

George

ImageImage
Last edited by surfingslovak on Fri Mar 30, 2012 12:31 pm, edited 1 time in total.

lukati
Posts: 288
Joined: Wed Aug 17, 2011 3:23 pm
Delivery Date: 07 Dec 2011

Re: Better (reverse) SOC meter already in the car?

Fri Jan 13, 2012 10:28 am

surfingslovak wrote:This took a lot more effort than I anticipated, but here are my preliminary results.
Definitely worth the wait! Looking great.

User avatar
DaveEV
Forum Supporter
Posts: 6237
Joined: Fri Apr 23, 2010 3:51 pm
Location: San Diego

Re: Better (reverse) SOC meter already in the car?

Fri Jan 13, 2012 11:56 am

surfingslovak wrote:This took a lot more effort than I anticipated, but here are my preliminary results.
Thanks for the work and the chart! I'm checking the chart against what's reported by Carwings and matches up for me (currently reports 8 bars, 7.5 hours 120V, 2.5 hours 240V). Was confused for a bit because Carwings reports time to 100% even though my timer is set to 80% 7 days a week.

User avatar
surfingslovak
Vendor
Posts: 3809
Joined: Mon Jun 13, 2011 1:35 pm

Re: Better (reverse) SOC meter already in the car?

Fri Jan 13, 2012 6:07 pm

lukati wrote:Definitely worth the wait! Looking great.
Thank you, much appreciated! I found the data analysis you did earlier in the thread very useful.
drees wrote: Thanks for the work and the chart! I'm checking the chart against what's reported by Carwings and matches up for me (currently reports 8 bars, 7.5 hours 120V, 2.5 hours 240V). Was confused for a bit because Carwings reports time to 100% even though my timer is set to 80% 7 days a week.
Yes, that's good to hear and thank you for your patience. Carwings has a number of quirks, and this is definitely one of them. It does not respect the 80% charge timer, and it always shows the time needed for a 100% charge.

I would like to refine both the model and its presentation. It will be crucial to have access to more data, and if you were able and willing to help out, that woud be much appreciated. I plan to make the spreadsheet available both on the web and in the form a mobile app. Beta testers would be greatly appreciated.

User avatar
surfingslovak
Vendor
Posts: 3809
Joined: Mon Jun 13, 2011 1:35 pm

Re: Better (reverse) SOC meter already in the car?

Tue Jan 17, 2012 9:19 pm

A new version of the chart is available on Google Docs. I cleaned up and reformatted the spreadsheet, and both the estimated usable battery capacity and energy economy can be easily accessed and edited. This should help tailor range estimates to your car and driving conditions. I did not have time to refine the underlying model, although I would like to do that in the not too distant future.

If you would like to edit the spreadsheet online, you can do that for the time being. It's important to demo the potential of this approach, but I might have to restrict access if things get out of hand. Obviously, you can always download a copy and use as you seem fit. Thank you to everyone who has sent a PM, your feedback and correction requests are greatly appreciated.


Image
Last edited by surfingslovak on Fri Mar 30, 2012 12:29 pm, edited 1 time in total.

User avatar
surfingslovak
Vendor
Posts: 3809
Joined: Mon Jun 13, 2011 1:35 pm

Re: Better (reverse) SOC meter already in the car?

Fri Feb 10, 2012 5:06 pm

The discussion initiated by Phil in another thread and the data presented there prompted me to update the spreadsheet. Version three is now available on Google Docs.

The revelation that Gids represented stored energy and corresponded to 80 Wh, allowed me to come up with an fairly simple model, which I used to replace the empirical data I've collected over the course of two months almost seamlessly. I feel much more confident about the data presented in the spreadsheet now, although the mapping to battery bars is still a bit iffy. I pulled up Tony's range chart as a reference, and tried to fix it, but ran out of time and had to admit defeat on that front.

The SOC column has been renamed to indicate that it's only an estimate, since we cannot reliably derive a true SOC reading from Gids or the hours on the charging time display. This estimate equates 300 Gids to 100% SOC, and it assumes that there is no additional reserve beyond the 4 Gids remaining in the battery when the car stops dead after turtle.

I've created a new column that indexes the energy available to the driver from 100% to 0. Perhaps this will be more useful than what we had previously. And finally, I've included a column with Gids. This is based purely on the assumption that each hour on the charing time display is 11 Gids. Surprisingly, this simple model, combined with the observation that there are 25 hours max on the display, delivers unexpectedly good results. It predicts 232 Gids for an 80% charge, where I typically observed 231. It also predicts the Gid value for LBW and VLBW quite accurately.

I moved the 25-hour mark down a notch to indicate that the car can enter power-restricted mode (announced by disappearing power bubbles) a bit earlier. This was driven by the model, which predicts very low energy at the 25th-hour mark. I observed this twice, most recently in January. On another occasion, I was able to drive a mile or two beyond this mark without any trouble. In any case, the car won't go very far once you see 24 hours on the charging time display.

Your feedback and correction requests are greatly appreciated.

Image
Click to open
Last edited by surfingslovak on Fri Mar 30, 2012 12:29 pm, edited 1 time in total.

shtimseht
Posts: 12
Joined: Fri Jan 21, 2011 9:10 pm

Re: Better (reverse) SOC meter already in the car?

Sun Feb 12, 2012 8:24 am

Thanks for posting these range estimation charts. I used them yesterday and they worked great. I noticed that there is another post that mentions a voluntary recall to update the calculation on the "time to charge" display.

http://www.mynissanleaf.com/viewtopic.php?f=27&t=7861" onclick="window.open(this.href);return false;

Anybody know more about this or have this service performed on their leaf? Did it make a difference in the carts predicted range?

User avatar
surfingslovak
Vendor
Posts: 3809
Joined: Mon Jun 13, 2011 1:35 pm

Re: Better (reverse) SOC meter already in the car?

Sun Feb 12, 2012 10:01 am

shtimseht wrote:Thanks for posting these range estimation charts. I used them yesterday and they worked great. I noticed that there is another post that mentions a voluntary recall to update the calculation on the "time to charge" display.

Anybody know more about this or have this service performed on their leaf? Did it make a difference in the carts predicted range?
Thank you for your feedback. Glad to hear that you found this information useful. If you saw any inaccuracies or room for improvement, please let me know.

User avatar
planet4ever
Posts: 4674
Joined: Sat Apr 03, 2010 9:53 pm
Delivery Date: 02 May 2011
Leaf Number: 1537
Location: Morgan Hill, CA, south of San Jose

Re: Better (reverse) SOC meter already in the car?

Sun May 06, 2012 9:39 pm

I've been ignoring your research on this, but finally decided it was time I paid attention. I have two questions:
  • Are the Gids shown the max, mid, or min for the time? e.g. if Gids=218, would you expect to see 1:30 or 2:00 for a 80% charge?
  • Your chart clearly shows an "80%" charge as 80% of usable. Phil (Ingineer) has told us that it is really 80% of SoC. (See this post.) That would put it at about 85% of usable. Has your testing shown convincingly that he is wrong for once?
Ray
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

Return to “Tips & Tricks”