arnis
Posts: 751
Joined: Sat Jan 23, 2016 3:21 pm
Delivery Date: 23 Jul 2014
Leaf Number: 015896
Location: Estonia, Europe

Same trip, incorrect average consumption, observations

Sun Jan 22, 2017 9:34 am

So I went for a drive today. 95.7km there and 95,7km back (59,5 miles), no elevation. (Google Maps data 92km, doesn't apply for calculations)
Started with 95%, 19.9kWh. Battery at 9,5C 9,5C, 6,9C. Ended with average 16,5kWh/100km, 1.6kWh left, battery at 16,2C 16,0C, 12,8C. Average heat gained 6*C. Outside temperature 1*C.
Charged on full speed 50kW charger. Got to 95% in exactly 40 minutes (from 7% to 95%).
Left charger after 58 minutes at 100% SOC, battery at 25.4C 25.5C, 20.3C. Average temperature gain during 1 hour session 9*C
Arrived home with 12%, 2.6kWh, average 16.4kWh/100km, battery at 26,4C 25,5C 19,2C (PS! temperature was absolutely stable down to 25% SOC, it went down 1C after charging session and stayed there).
Just drained the battery at nominal speed to verify range, ran back and forth near home. (PS! battery heated up to 28,9C, 28,5C 21,4C, this proves my previous observations that after LBW battery heats up extremely fast, this does not happen at very high SOC!!!)

Now if I look at both promised averages 16,5kWh/100km and 16,4kWh/100km, multiply it with distance travelled (95km), I get promised capacity loss of 15,8kWh and 15,7kWh.
When I went I started with 19.9kWh and ended with 1,6kWh, therefore 18.3kWh real loss (cabin was not preheated)
When I came I started with 20,7kWh and ended with 2.6kWh, therefore 18,1kWh real loss.
There is 20% inconsistency between promised energy usage and real loss. What's going on?
Data on speedo does include cabin heating. It levelled out at 350W during 90% of travel, cabin warm. Both directions took 1 hour 9 min (+/- 1 minute). Therefore energy loss due to heating less than 0,5kWh, outside temperature +1*C, cabin warm :shock:

Observations:
It was possible to travel around 100km in this scenario (1*C, wet road, full speed 90-100km/h GPS) from 100% down to turtle. Same road in summer I was able to travel 120km. Therefore 15% loss of range due to studded tires and wet road, most likely air density/humidity as well. Like I said heating required less than 0,5kWh, which is unbelievable actually.
Range didn't get better due to warm battery. It appears 10C is enough and there is no noticeable range gain due to battery being any warmer. Would be awesome to reproduce at colder chemistry temperature.
4 battery bars was enough to get Leaf to charge at really fast speed (105-120A). This doesn't happen with 3 bars, aka battery between 5-15C.
It appears that 25*C above ambient is equilibrium temperature (cooling due to driving and heat generation due to driving are almost equal).
Discharge below 1/4 will have noticeable higher heat generation, especially below LBW. Take that into account during hot summer, longer trips with DC charges.

I'm charging at the moment at 3.3kW. Will share cooldown data later.

EDIT: after 3 hour charge battery cooled down to 21,0C, 20,2C, 14,2C, therefore cooled on average 8*C, aka 3 degrees per hour
Another 2.5 hours and more cooling, down to 17,8C, 17,1C, 11,4C, therefore cooled on average 3*C, 1 degree per hour
Ambient still at 1*C.
Drove again from 80% down to VLBW, 7%. From 80% to LBW temperature was stable (cooled further for half of degree) but went up
from LBW to VLBW on average 2*C. 19,7C, 18,7C, 13,0C. Like I said, driving below 25% will generate a lot of heat.
Short range EVs <30kWh -- Medium range: 30-60kWh -- Long range: >60kWh
Charging: Trickle <3kW -- Normal 3-22kW -- Fast 50-100kW -- Supercharging >100kW

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