awolfe63
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Fri May 27, 2011 8:16 pm

Update:

Nissan tested my car - but I have received little feedback. The dealer indicated that a Nissan engineer would call me but despite 2 reminders, it has not happened. The communications through the dealer were unhelpful. They said that the problem was that I had the timer set to 80% and if I wanted more range I should just set it to 100%. I knew that. My concern was my total battery capacity.

However, since then I have done some more testing and my results are very similar to everyone else's.

Ran battery down to 0 bars, "---" on miles-to-go, very low battery warning.
Charged on 120 through a Kill-a-Watt to 100%.

Kill-a-Watt read 25.95 kWh. Pretty similar to what others have seen. If the charger is 85% efficient, that is 22kWh usable. It definitely is not near 18kWh as I had feared. As others have noted, both the bars remaining and the miles-to-go appear to be very non-linear.

Also - I got about 6-7 more miles when the readout read 4 miles-to-go and Carwings reported that I still had a range of 2.

DaveinOlyWA
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sat May 28, 2011 6:07 am

awolfe63 wrote:Update:

Nissan tested my car - but I have received little feedback. The dealer indicated that a Nissan engineer would call me but despite 2 reminders, it has not happened. The communications through the dealer were unhelpful. They said that the problem was that I had the timer set to 80% and if I wanted more range I should just set it to 100%. I knew that. My concern was my total battery capacity.

However, since then I have done some more testing and my results are very similar to everyone else's.

Ran battery down to 0 bars, "---" on miles-to-go, very low battery warning.
Charged on 120 through a Kill-a-Watt to 100%.

Kill-a-Watt read 25.95 kWh. Pretty similar to what others have seen. If the charger is 85% efficient, that is 22kWh usable. It definitely is not near 18kWh as I had feared. As others have noted, both the bars remaining and the miles-to-go appear to be very non-linear.

Also - I got about 6-7 more miles when the readout read 4 miles-to-go and Carwings reported that I still had a range of 2.
hate to burst your bubble, but many of us have found the 120 volt efficiency to be around 75% so you would have around 19.5 KWH used.

the charger has set overhead beside charging inefficiencies. have talked with several friends of mine who are familiar with small motor controls and systems and estimates vary but i am looking at a charging efficiency of probably 88-90% then a set overhead for the charge management (which should be small) and cooling system which is small but still significant.

so the longer the charge time, the greater the hit on the overall charging efficiency. most have seen 85-88% on 240, around 75% on 120.

having run several timed tests over the past few weeks i am charging around 1350-1380 watts/hour so the charger overhead is about 350 watts.

so on a set charge at 240 for say 7 hours we are looking at about 21000-2450 watts dissipated to overhead. if charging around (pure guess here since i dont have one) 3300 watts which is a figure tossed around, real terms are probably slightly less so set overhead at that would be 88%

with the trickle down charge rate, the efficiency would be lowered and that probably how many are seeing the lower 85%.

so there is other advantages to not charging to 100%.
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 3500.3 mi, 96.95% SOH
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gascant
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sat May 28, 2011 10:22 am

Ingineer wrote: I would assume the LEAF's on-board charger is somewhere from 80%-90% efficient. I seriously doubt it's over 90%! So take that into account as well. The energy going in is always more than coming out!

-Phil
Wow, if it's that bad, then it explains the difference between my driving mi/kWh and consumed mi/kWh. I just posted on that in the "Owners what range" thread. I have 2 weeks worth of data.

The solar energy industry would never survive if inverter efficiencies were in the 80-90% range! Oh, wait, maybe our on-board inverters also lose 5%?
2011 LEAF SL brilliant silver + QC
DRL's, Seat Heaters, Horn, LEDs and EVSE upgrades
Over 24,300 miles gas-free
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LEAFguy
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sat May 28, 2011 4:15 pm

planet4ever wrote:I won't bore you with all the data, but here is the bottom line for this post:
  • Starting condition: Fully charged with unmodified Nissan L1 EVSE, reset trip odometer and m/kWh meter in dash.
  • Ending condition: 42.0 miles, 5.0 m/kWh, 7 SoC bars (fifth one lost at 39.9 miles).
  • Recharge: To full charge (after 3 charging lights in the car went off), same L1 EVSE through Kill A Watt, 11.04 kWh.
(42.0 miles) / (5.0 m/kWh) = 8.2 kWh
(8.2 kWh) / (11.04 kWh) = 74%

Either Dave's and my Kill A Watts are both grossly inaccurate, or the m/kWh meter in the dash is grossly inaccurate or the charger is grossly inefficient at 120v.
This was mentioned long ago in this thread, and is something that few have considered (it seems) since that post (regarding wall to wheels power usage):

Power comes out of the wall, through the Blink (or L1 EVSE, or Clipper Creek, or whatever), through the onboard charger into the battery (converted from AC to DC). Power comes out of the battery, through the inverter, into the motor (converted from DC to AC). Both the charger and the inverter have losses. The total losses approximate 74% based on the above example.

My belief is that none of the discussion in this thread matters - in the real world. What matters to me is energy use per mile. How far did I drive, and how much electricity did I use to recharge. I don't really care what the battery capacity is - usable or otherwise. Based on real-world observations, I can make a reasonable determination how much further I can drive.

Said another way - I don't care if my car has an 18, 19, or 20 gallon gas tank. Based on my driving style, I can see how fast I am depleting my gasoline supply by looking at the gas gauge. While the LEAF offers only a crude equivalent to the gas gauge (12 bars), if over 2 months worth of driving, I average 5 to 6 miles per bar, I can reasonably expect to continue to get 5 to 6 miles per bar. I don't really care how big the "tank" is. There should be a way to turn off the miles remaining display, as it is worse than useless, inspiring false confidence - especially in those expecting it to be accurate.

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evnow
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sat May 28, 2011 5:40 pm

LEAFguy wrote:Said another way - I don't care if my car has an 18, 19, or 20 gallon gas tank. Based on my driving style, I can see how fast I am depleting my gasoline supply by looking at the gas gauge. While the LEAF offers only a crude equivalent to the gas gauge (12 bars), if over 2 months worth of driving, I average 5 to 6 miles per bar, I can reasonably expect to continue to get 5 to 6 miles per bar. I don't really care how big the "tank" is. There should be a way to turn off the miles remaining display, as it is worse than useless, inspiring false confidence - especially in those expecting it to be accurate.
I find it impossible to keep track of how many miles I get per bar. But using all the information here - I now have a very good idea of my range based on the m/kwh I'm getting in any trip.

Starting at 100% charge, just multiply the m/kwh with 20 (or 21). You get a good idea about the total range you are getting.
1st Leaf : 2/28/2011 to 5/6/2013
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JessEV
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sun May 29, 2011 12:43 am

Hi, I'm cross posting this here:

http://www.mynissanleaf.com/viewtopic.p ... 043#p97043

Basically, I'm seeing 2.2 to 2.5 miles/kWh resulting in a total real range for me of 50 miles.
OR, the battery pack isn't 24kWh.
I will be measuring tonight what goes in to the pack from the walls (assuming 75% eff on my L1) to bring it back up to 80%. This will be interesting.


Jess

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evnow
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sun May 29, 2011 1:03 am

JessEV wrote:Basically, I'm seeing 2.2 to 2.5 miles/kWh resulting in a total real range for me of 50 miles.
OR, the battery pack isn't 24kWh.
Or your assumption about bars is wrong.
1st Leaf : 2/28/2011 to 5/6/2013
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JessEV
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sun May 29, 2011 1:27 am

evnow wrote:
JessEV wrote:Basically, I'm seeing 2.2 to 2.5 miles/kWh resulting in a total real range for me of 50 miles.
OR, the battery pack isn't 24kWh.
Or your assumption about bars is wrong.
Yes I was going to add that explanation tomorrow... But since you mentioned it :)
My assumption is that each bar represents 2kWh since there are 12 and it is a stated 24kWh battery. The bars could also represent charge on a non-linear scale or somehow offset by some buffer at the bottom of the scale.

After 8.5 hours of charging on L1, I have recovered 7 bars. At 1.33kWh * 8.5 I got 11.3kWh from the wall. With the 25% loss that others have stated I'm at 8.5kWh into the battery. So now things are looking like each bar is only 1.2kWh?? Or if it's only a 15% loss for L1, then it's 1.4kWh per bar?? Either way it does seem 2 is wrong.

So now I'm left wondering if the battery pack is 12 bars x 1.2 = 14.4kWh? (No way)
or
There is a reserve not shown in the bars...

Anyone taken it all the way to dead stop after the AC bug fix? And then measured what went in? I saw a bunch of these numbers in earlier posts but didn't see if they were on post-AC bug fix.

Jess
PS: I should add my Leaf is being charged outside my garage where it is currently 45F
PPS: if I split the diff on kWh per bar and call it 1.3kWh/bar then the dashboard number of 3.4miles/kWh is spot on (I drove 35 miles and used 8 bars)

DaveinOlyWA
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sun May 29, 2011 5:46 am

recovering 7 bars could really mean nearly 8 or just over 6. that is how those gauges work.

its like trying to put 22 gallons of gas in the a 22 gallon tank. we have all tried that and how many times have we been successful? not many

but we do know that we drive 500 miles and last fillup was about 10 gallons and we are getting about 50 mpg and sure enough, we will get about 10 gallons this time as well.

your Leaf is the same. that is why i chart my driving daily. i log how far i went, the MPK per the car, and KWH out of the wall. if you are primarily using L1 charging, i strongly recommend getting a Kill a Watt meter. it tracks your power used and its like $20
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 3500.3 mi, 96.95% SOH
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Herm
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Re: Leaf Miles / KWh is Wrong Or Usable bat. cap. is not 24

Sun May 29, 2011 7:46 am

DaveinOlyWA wrote: hate to burst your bubble, but many of us have found the 120 volt efficiency to be around 75% so you would have around 19.5 KWH used.
... i am looking at a charging efficiency of probably 88-90% then a set overhead for the charge management (which should be small) and cooling system which is small but still significant.
so the longer the charge time, the greater the hit on the overall charging efficiency. most have seen 85-88% on 240, around 75% on 120.
I'm ok with the efficiency numbers for typical power supplies and chargers, but the 350w fixed overhead sounds a bit too high.. but in any case is all a case of circular logic since NO ONE has measured the wattage going in and out of the battery while being charged.. who will be the first dedicated Lead owner to actually make some measurements?

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