My Experiments With Turtle
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DaveinOlyWA
Well-known member
geeuz!! take a bit of time to clean the garage for the Leaf and all hell breaks loose.
ok, so now we go from minimal battery pack to a very bad charging efficiency? we still cant ignore his 4 mpk average proving he used around 19 kwh. which means a charging efficiency below 80%?
we need data fast!! i need to get my Leaf and track both charge used and charge in.
ok, so now we go from minimal battery pack to a very bad charging efficiency? we still cant ignore his 4 mpk average proving he used around 19 kwh. which means a charging efficiency below 80%?
we need data fast!! i need to get my Leaf and track both charge used and charge in.
Jimmydreams
Well-known member
DaveinOlyWA said:
Well, when you get your Leaf, you'll realize how fluid all the data can be.
I'm GUESSING my mi/kW on Turtle Day was around 3.6-3.8 range. Going to Turtle Mode was completely spontaneous, so I wasn't keeping accurate numbers/data on the event.
So I don't think 'we need data fast' unless you're figuring to do something with your Leaf that Nissan didn't think of. I got 83 miles out of my car....Nissan says "up to 100" and EPA said, what? 74? hills, climate control, lead-foot disease, outside air temp..... all of that can skew this data pretty fast.
Take my data with everyone else's, mix, analyze. Repeat.
Spies
Well-known member
If you did really manage to get down to 0% of the assumed 24 kWh of the useable pack and it took 25.6 kWh at the EVSE to charge it back to 100% that would result in a charge efficiency of 93.375% if I am not mistaken. I admit I don't know what kind of losses are expected from the EVSE through the charger and into the pack but it does not sound unexpected to me.Jimmydreams said:
I still wonder what the two spikes after the initial charge are all about. I wonder if they are to squeeze as much energy into the pack after the pack has cooled down/equalized when charging to 100%. I wonder if the spikes would still be present if using the timer to only charge to 80%. I think someone may have already posted this data but I can't seem to find it at the moment.
AndyH
Well-known member
So far, gents, these numbers are fitting perfectly. The 'fuel gauge' bars in the car show the 24kWh usable capacity from the pack. The bars to the last two adjacent to the red bars, show us 20kWh.
There's still room above and below for the approx 10% of capacity we've been told from the beginning that we're not allowed to use.
- Early AESC cells were straight LiMn2O4, but current cells have some nickel and cobalt in the mix. This changes cell voltages a bit (increases nominal and raises the upper limit).
- Current cells (LiNiMnO4) can be charged up to a bit above 4.4V and can be discharged down to below 2.5V.
- The BMS reports 5% SOC is 3.2-3.4V per cell and 95% is 4.0-4.2V per cell.
- These cells carry more of their energy at the upper end so it makes sense that the 10% 'extra' would have a larger voltage gap at the bottom and smaller at the top
So far the pieces seem to be falling into place nicely!
This also seems to confirm that AESC's reported 33Ah per cell is the 'consumer' capacity and not ultimate; they're not the only company to report numbers this way on public websites and/or publically available data sheets.
Links:
http://www.rosebatteries.com/newsletters/E-newsletter33.pdf
http://www.greencarcongress.com/2008/05/aesc-lithium-io.html
http://www.eco-aesc-lb.com/en/bmodule.html
There's still room above and below for the approx 10% of capacity we've been told from the beginning that we're not allowed to use.
- Early AESC cells were straight LiMn2O4, but current cells have some nickel and cobalt in the mix. This changes cell voltages a bit (increases nominal and raises the upper limit).
- Current cells (LiNiMnO4) can be charged up to a bit above 4.4V and can be discharged down to below 2.5V.
- The BMS reports 5% SOC is 3.2-3.4V per cell and 95% is 4.0-4.2V per cell.
- These cells carry more of their energy at the upper end so it makes sense that the 10% 'extra' would have a larger voltage gap at the bottom and smaller at the top
So far the pieces seem to be falling into place nicely!
This also seems to confirm that AESC's reported 33Ah per cell is the 'consumer' capacity and not ultimate; they're not the only company to report numbers this way on public websites and/or publically available data sheets.
Links:
http://www.rosebatteries.com/newsletters/E-newsletter33.pdf
http://www.greencarcongress.com/2008/05/aesc-lithium-io.html
http://www.eco-aesc-lb.com/en/bmodule.html
Jimmydreams
Well-known member
Spies said:
Going ONLY by the charge this morning (which was remotely initiated through my iPhone ap), there were no associated 'after-spikes'. You'll notice on the graph that today's charge was one big charge with a trickle-stop.
In the coming days, I plan on testing timed start-stop and simple charge-now events to see if these aftter-spikes occur. They seem to be some form of battery equalization....
garygid
Well-known member
What caused the two spikes around 16:00 at thr left end of your (very nice) graph?
Now, we have seen one spike and two spikes after the main charge.
My GUESS is that the "off" period is a "balancing" time where the "most filled" cells lose energy to make them closer to the "lower" cells. Then, to "top-up", we see a short after-balance charging to bring up all the cells a bit. If there is still too much imbalance, the cycle apparently repeats, with another "equilization" period followed by another "top-up".
If one is charging to 80%, the small equilization loss is just tolerated, quite possibly with equilization done, but no "top-up" spike.
Now, we have seen one spike and two spikes after the main charge.
My GUESS is that the "off" period is a "balancing" time where the "most filled" cells lose energy to make them closer to the "lower" cells. Then, to "top-up", we see a short after-balance charging to bring up all the cells a bit. If there is still too much imbalance, the cycle apparently repeats, with another "equilization" period followed by another "top-up".
If one is charging to 80%, the small equilization loss is just tolerated, quite possibly with equilization done, but no "top-up" spike.
evnow
Well-known member
Assuming Gary's equalization theory is correct - I can see why there were equalization after the pack had gone to turtle mode, and not on other days.
In other words, don't get to turtle mode often.
In other words, don't get to turtle mode often.
Jimmydreams
Well-known member
evnow said:
Turtle-mode gave me two EQ-spikes. A few days ago, telling the charger to charge to 100% with only an end time programmed resulted in 1 EQ-spike. I'll do the same tonight and see if we get another 1 EQ-spike.
And yeah, hitting Turtle-mode oughta be last-resort time!!
Boomer23
Well-known member
Jimmydreams said:
Jimmy, I found it amazing when I was setting up my own TED that the Footprints software doesn't have a real-time usage since midnight total. Having to add hourly segments is so unsophisticated. Luckily I found the "Ted-O-Meter" iPad/iPhone app. It's free and part of its displays is a real time usage or solar generation number since midnight of the current day. Really handy app.
Jimmydreams
Well-known member
Boomer23 said:
Adding up the hourly numbers IS a pain. I look at each charge 'event' as covering the previous days mileage, so even though TED makes me do the addition, my charge always straddles midnight. I have the iphone ap, so I'll look at that a little closer. You can also export second/minute/hourly data from the TED utility screen. So if I ever get the time, I might try downloading that info and creating a spreadsheet that will automatically do the math for me. :?
DaveinOlyWA
Well-known member
ok just returned from trip to Renton for NW leaf meet. RT 122.8 went to blinking range at 118.2 so more than 4½ miles in "turtle mode. by then i was already on streets at 35 mph so did not notice loss of power but then again, did not need it!!
now at 122.8 miles we need a "drove the most in one day" contest!!
now at 122.8 miles we need a "drove the most in one day" contest!!
evnow
Well-known member
Good you made it back !DaveinOlyWA said:
Let us know how much is the full charge kwh.
garygid
Well-known member
122 miles on ONE charge?
Jimmydreams
Well-known member
DaveinOlyWA said:
YIKES! Very nice indeed!! You did 4.5 miles with the yellow Turtle lit? That's good to know.
You win for furthest miles on one charge so far!! :mrgreen:
hobbyguy
Well-known member
oooh, I wanta play too! We should see who can get the most mileage on a 100% charge 
planet4ever
Well-known member
Any tips you'd like to share with us? Did you travel most of the way on I-5? What speed? Did you use ECO or cruise?DaveinOlyWA said:
Ray
DaveinOlyWA
Well-known member
well, actually, i did plug in at Younkers for an hour then did the meet and then had to re-sign my paperwork AGAIN, so went to Rairdons and plugged in almost an hour there before heading home.
but went I-5 to 18 to 167 and reversed that on the way back. this was shortest route by 3 miles.
i always drive in eco mode. i find that drive is too responsive and much harder to control speed although there are times when i will use it at lights to show off
as far as the recharge, i wont have it charged to 100% before i leave for work tomorrow, so will have to average it over 2 days to find out.
but went I-5 to 18 to 167 and reversed that on the way back. this was shortest route by 3 miles.
i always drive in eco mode. i find that drive is too responsive and much harder to control speed although there are times when i will use it at lights to show off
as far as the recharge, i wont have it charged to 100% before i leave for work tomorrow, so will have to average it over 2 days to find out.
garygid
Well-known member
Oh, around 2 hours of extra charging (add about 25% extra e-fuel) ... makes your distance easier to understand, but still very good!
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