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TickTock
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Location: Queen Creek, Arizona
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 8:31 am

Using two diffrent canbus logs (one as I drove the car from GOM=6 to dead (discharge) and the other logged during a charge to 100%(charge)) I was able to plot battery voltage versus gids across the full range (keep in mind my 100% charge stops at 244 NOT 281 like most of you). I was able to empirically establish that the ESR of the battery (and any wire between the sense point and the battery) to be about 70mOhm since any value higher or lower resulting in larger variation in the formula (battery_volts-battery_amps*esr) during my discharge log. I also labled the points where I recieved LBW, VLBW, turtle, and dead. As you can see once you get VLBW, you are past the knee and really need to stop driving or you can degrade your weakest cells by over discharging.

Image

Stoaty
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Leaf Number: 3871
Location: West Los Angeles

Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 8:57 am

TickTock, thanks for posting this. I was going to do a similar graph with my SOC meter, but you saved me the trouble. I expected more of a shoulder at the top end, though.
2011 Leaf with 62,000 miles given to Nephew
2013 Tesla Model S85 with 251 miles rated range at full charge
Leaf Spy Manual
Battery Aging Model Spreadsheet

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TickTock
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Delivery Date: 31 May 2011
Leaf Number: 3626
Location: Queen Creek, Arizona
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 9:00 am

If you can send me the logs, I'd be happy to generate the plot. I think it would be good to get another set of data from a more "normal" battery since mine seems to be an outlyer.

Herm
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 9:01 am

Thanks Tick
Not a good idea discharging past the first warning.. the fact that so many people do it routinely means Nissan is doing a very good job matching cells. Will the cells remain matched as they age?

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TickTock
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 9:06 am

Stoaty,
If you prefer, I posted some perl code here if you want to save some time figuring out the log format:

http://www.mynissanleaf.com/viewtopic.php?f=44&t=6088

I'm using strawberry perl and notepad++ (both free).

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TickTock
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 9:25 am

One more datapoint. I also integrated the battery_volts*battery_amps*delta_time during the charge from 28 gids to 100% (244 gids). I got 18.2kWh actually going into the battery. My wall power meter read 19.9kWh for the same charge cycle. This comes to 91% charging efficiency. We've pretty consistently been coming up with ~85% total efficiency using the miles_driven/dash_efficiency compared to the wall power. So it looks like the driving efficiency is about 93%. Given the error bars, I'd call it ~92% efficiency each side. Some pretty good engineering on Nissan's part.

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surfingslovak
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 9:56 am

Awesome data, thank you for sharing all this!

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TonyWilliams
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 10:01 am

Truly great data! Thanks!!

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TickTock
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 11:25 am

Thanks to garygid for for providing the hardware and support!

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garygid
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Re: Only 18 KWh Usable Energy for MY Leaf--Retest Shows 20.3

Sun Oct 16, 2011 11:54 pm

Thanks.
A means of getting good data into the hands of the technically
curious (and capable) was one of my goals.

As interest grows, I hope we will have many good insights.
See SOC/GID-Meter and CAN-Do Info
2010 Prius, now for sale
2011 LEAF, sold in 2015
2018 Tesla Model 3
2014 Tesla S, Model 3 in 2019
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Solar PV: 33 x 225W -> 7 kW max AC
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