DaveinOlyWA
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Oct 15, 2012 6:58 am

Phil; any thoughts of internal losses after power is delivered in the battery; heat, etc? what percentage? even a ballpark figure would be appreciated
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 (build 10/2016)"low water marks" 27,000 miles.363GID Ahr 79.13Hx95.17%kwh28.1QCs238,L2's 251
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drees
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Oct 15, 2012 10:36 am

DaveinOlyWA wrote:Phil; any thoughts of internal losses after power is delivered in the battery; heat, etc? what percentage? even a ballpark figure would be appreciated

NREL LEAF Teardown and Detailed Testing
Energy from the wall from dead to 100%: 25.414 kWh
Energy from the onboard charger to battery: 22.031 kWh
Energy from the battery during discharge: 21.381 kWh

Of the energy pumped in to the battery, you get 97% out.
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DaveinOlyWA
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Oct 15, 2012 10:46 am

drees wrote:
DaveinOlyWA wrote:Phil; any thoughts of internal losses after power is delivered in the battery; heat, etc? what percentage? even a ballpark figure would be appreciated

NREL LEAF Teardown and Detailed Testing
Energy from the wall from dead to 100%: 25.414 kWh
Energy from the onboard charger to battery: 22.031 kWh
Energy from the battery during discharge: 21.381 kWh

Of the energy pumped in to the battery, you get 97% out.


Thanks for that!!
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 (build 10/2016)"low water marks" 27,000 miles.363GID Ahr 79.13Hx95.17%kwh28.1QCs238,L2's 251
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tbleakne
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Oct 15, 2012 12:15 pm

drees wrote:
DaveinOlyWA wrote:Phil; any thoughts of internal losses after power is delivered in the battery; heat, etc? what percentage? even a ballpark figure would be appreciated

NREL LEAF Teardown and Detailed Testing
Energy from the wall from dead to 100%: 25.414 kWh
Energy from the onboard charger to battery: 22.031 kWh
Energy from the battery during discharge: 21.381 kWh

Of the energy pumped in to the battery, you get 97% out.

I trust this result of 97% for overall average battery efficiency, but it is an average, because how you drive affects the battery discharge loss. As I have posted several times, the discharge loss as measured by the voltage sag under load is approximately 1% per 10 kW of delivered power. 20 kW is 2% or 400W, 30 kW is 3% or 900W, etc.

Similarly I believe the battery charging efficiency varies with charging rate. The difference may not be noticeable between L1 and L2, but it becomes important at L3 rates. The loss at a given L3 current rate also goes up with increasing SOC because the battery pack's charging impedance rises.
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jpa2825
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Oct 15, 2012 1:12 pm

If you are trying to make an argument to spend the $ to get an L2 charger / 240v outlet with EVSE Upgrade, can you very roughly & broadly assume a pickup of 15% efficiency of wall to wheel (90% v. 75%)?

If so, do you then simply run your calculations to show how many less kW you pull to charge the LEAF * the $/kW your energy provider is charging you to determine how valuable this efficiency is to you?

Without knowing what my next car will be, I am finding it hard to invest $1k + wiring (or even less via EVSE Upgrade) when the 120v existing outlet in my garage is meeting my needs (but restricting my flexibility).
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davewill
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Oct 15, 2012 4:28 pm

jpa2825 wrote:... Without knowing what my next car will be, I am finding it hard to invest $1k + wiring (or even less via EVSE Upgrade) when the 120v existing outlet in my garage is meeting my needs (but restricting my flexibility).
Sounds like a vicious circle. You're not using the car to it's potential because of L1, therefore, you're less likely to buy another EV next time, therefore you're reluctant to spend money on L2, therefore you're not using the car...
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DaveinOlyWA
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Oct 15, 2012 4:50 pm

With 120 volt charging you cannot use more than about 75% of your range on two consecutive days. It simply charges too slowly
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 (build 10/2016)"low water marks" 27,000 miles.363GID Ahr 79.13Hx95.17%kwh28.1QCs238,L2's 251
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dglaser
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Apr 29, 2013 9:02 am

I am so happy to know about these findings! Based on the information that Phil collected, is it correct to assume that the 6.6 kW Level 2 charging on the 2013 Leaf would be closer to 95% efficiency (i.e. 6.3/6.6=.95)?

BrockWI
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Mon Apr 07, 2014 7:41 pm

jpa2825 wrote:If you are trying to make an argument to spend the $ to get an L2 charger / 240v outlet with EVSE Upgrade, can you very roughly & broadly assume a pickup of 15% efficiency of wall to wheel (90% v. 75%)?

If so, do you then simply run your calculations to show how many less kW you pull to charge the LEAF * the $/kW your energy provider is charging you to determine how valuable this efficiency is to you?



This was my thought from the get go. I might have some math wrong here and correct me if I do. The problem here is it isn't just the 15% loss on the straight charging, besides that lets look at 5 days of charging for a 40 mile commute. Assuming you can run, lets say 4 miles/kwh that is 10kwh a day, so to speak. Now charging back up from level 1 you need to charge for approximately 9 hours at 300w / hour loss or 2700w lost on an overnight charge. That same charge at 6.6kw would take at max 2 hours or 600w lost. This same trip repeated 5 times a week turns in to 13.5 kwh lost for 120v charging and just 3 kwh for the 240v charging or a savings of 10kwh a week or 40kwh a month. To me that adds up pretty quick and we run closer to 80 miles a day, doubling all this.

Not to mention the ability to throw 6 kwh or 20+ miles in over lunch or dinner and keep using the leaf instead of pulling out an ice.
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DaveinOlyWA
Posts: 12313
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Re: Leaf Charging Efficiency - Lab Test (and Idle power draw

Tue Apr 08, 2014 7:13 pm

dglaser wrote:I am so happy to know about these findings! Based on the information that Phil collected, is it correct to assume that the 6.6 kW Level 2 charging on the 2013 Leaf would be closer to 95% efficiency (i.e. 6.3/6.6=.95)?


probably closer to 90-91%. I am getting right at 90% running at 4.8 kw. i tried 5.76 for 4 days charging at least 15 kwh a day and saw no real change
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 (build 10/2016)"low water marks" 27,000 miles.363GID Ahr 79.13Hx95.17%kwh28.1QCs238,L2's 251
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