Poor mans SOC meter

[bernie82]

BATTERY CAPACITY RANGE TEST
7 MONTH OLD LEAF WITH 6000 MILES
BATTERY CHARGED TO 100%, BALANCED FOR 5 HOURS, & RECHARGED AGAIN TO TOP OFF.
RESET TRIP ODOMETER, TRIP COMPUTER MILES / KWH RATIO
DRIVING CONDITIONS: AMBIENT TEMPERATURE 45 degrees F, LEVEL TERRAIN
TIRES INFLATED TO 42 PSI
CLIMATE CONTROL, STEERING WHEEL HEATER, SEAT HEATERS, AND HEADLIGHTS ALL OFF
SPEED 60 MPH SET BY CRUISE CONTROL ON 99 FREEWAY FROM ELK GROVE TO STOCKTON AND BACK
**************************************************************
MILES FROM ODOMETER 79.6 AT END OF ROUND TRIP TEST
MILES /4.1 MILES /KWH ON TRIP COMPUTER
LBW CAME ON AT 8 MILES ON TOUCH SCREEN WITH 71 MILES ON ODOMETER
VLB came on with 76 miles on the odometer
I drove around the block a few times and turtle came on 50 feet from my garage with 79.6 on the odometer.

BATTERY CAPACITY ADJUSTMENT FOR AMBIENT TEMPERATURE
21 kwh * 94% = 19.74 KWH
TRIP BATTERY CAPACITY 19.74 KILOWATTS
MILES RATIO (4.1M/KWH) * 19.74 = 80.93
LEAF should have gone 80.93 to turtle with 21 KWH. It went 79.66
CONSIDERING 4.1 M/KWH COULD BE ANYWHERE FROM 4.1.0 TO 4.14 AND THE AMBIENT TEMPERATURE FORMULA MAY BE SLIGHTLY OFF AS WELL AS THE ODOMETER, I FIGURE THERE'S NO BATTERY DEGRADATION YET.

 

[TonyWilliams]

Wow, you've been paying attention!!!

One quibble. Was the car exposed to 45F prior to the test, or was it in a garage that may have been warmer?

 

[edatoakrun]

While your LEAF obviously has not yet lost significant battery capacity, the weak point in your analysis, IMO, may be in assuming your 4.1 m/kWh figure is correct.

The Arizona range test showed variations in reported m/kWh of 3.7 to 4.4 in a test which normalized most efficiency variables between the dozen LEAFs.

http://mynissanleaf.com/wiki/index.php?title=Battery_Capacity_Loss" onclick="window.open(this.href);return false;

So, either the LEAFS themselves varied a great deal in efficiency, the drivers’ efficiency did, the variables not controlled (such as battery temperature) must have been far more significant than expected, or the m/kWh reports of some of the LEAFs were inaccurate, as is very likely, IMO.

You might also want to read this thread, which reports my own range tests, similar to your own, and explains why I believe the m/kWh reports from my own LEAF may have varied significantly over time.

http://www.mynissanleaf.com/viewtopic.php?f=31&t=9064" onclick="window.open(this.href);return false;


Please continue to test, to watch for changes in either your range or your m/kWh over time. It sounds like you may have easy access to a constant-speed and near-level route, which many (like me) don't.

You may also want to utilize Carwings, both for the convenience and accuracy of kWh use data (rather than calculations using m/kWh from the dash or nav screen) and because the CW regeneration kWh reports are the only way I am aware of to assess variable driver efficiency, though yours would probably not vary much, if you keep it on CC for all the tests, on the identical route.

I have suggested many times, that new LEAFs (I started my own tests after most of a Summer and ~3,300 miles had passed) should be range tested and retested over time, to show actual loss of range and capacity.

But despite the Sturm und Drang over capacity loss, no one on this forum has actually made the effort to collect and report results from such a series of range tests, AFAIK.

 

[bernie82]

The leaf was charged outdoors before the trip. The accuracy of the M/KWH is irrelevant because the trip was done using cruise control set a 60MPH. Driving 79 miles at 60 MPH, it's safe to say my battery capacity is still close to 21KWH.

 

[LEAFfan]

The leaf was charged outdoors before the trip. The accuracy of the M/KWH is irrelevant because the trip was done using cruise control set a 60MPH. Driving 79 miles at 60 MPH, it's safe to say my battery capacity is still close to 21KWH.

Remember, 60mph is really 59.

 

[TonyWilliams]

The leaf was charged outdoors before the trip. The accuracy of the M/KWH is irrelevant because the trip was done using cruise control set a 60MPH. Driving 79 miles at 60 MPH, it's safe to say my battery capacity is still close to 21KWH.

The "real" economy at 60mph is closer to 4.2 miles/kWh for the usual parameter (level, dry, 70F, etc). You got 4.1 pushing more dense 45F air than 70F.

4.8 miles/kWh - 50mph
4.4 miles/kWh - 55mph
4.2 miles/kWh - 60mph
4.0 miles/kWh - 65mph
3.6 miles/kWh - 70mph

As we learned in Phoenix, unfortunately different cars can vary SIGNIFICANTLY in the economy reading under the same cruise control set speed (and checked with GPS for ground speed). But, your 4.1 number seems very reasonable.

But, you are right, the gauge really doesn't matter if you drove steady speed until turtle. I would certainly want a Gid reading (which you seem to be getting) and I'd also do a charge from an EVSE that can give you the total kWh. Then use about 85% efficiency to determine what went in the battery.

Hopefully all three sources point to a very similar number.

79.6 on the odometer

*** Battery 60F**** Temperature (it was parked in a garage at that temp)
21 kwh * 97.5% = 20.475 KWH

(4.1 miles/KWH) * 20.475 = 83.95 miles
LEAF should have gone 83.95 to turtle with 20.475kWh

It went 79.6 miles, or 94.8% of 83.95 miles.

Looks like about 5% degradation to me. I predict 265-270 Gids when the temps are "normalized". Don't try and compare a Gid reading with a cool battery to one with a warm battery... they will be off.