Nissan Leaf Cells Test Data

BigRider said:
Gotcha. I'll go back to lurking-ish. Or sponging anyway :). Just trying to be helpful in the one area I can contribute on.
Click to expand...

:oops: I wasn't trying to say that, sorry. I only know what I have worked on, my knowledge base is peppered with large gaps and erroneous assumptions that your experience could correct, please speak up. :D

Besides, I think your trike project is going to be a major contribution, I think you might pave the way for other folks in your situation to find a way forward, or at the very least have better access to the world (which is a way forward in and of itself). You could find yourself becoming the founding father of a revolution!

-JD
 
@bigrider guy, the 4.2V limits you mentioned are the point at which the cell reaches full charge. there is a utube video on the tesla fan's website where some professor from a canadian university, de l houise or something like that has alecture about factors affecting lipo cycle life, and in the lecture he talks about the research he and his grad students did to determine cycle life and how additives to the electrolyte can change the number of cycle lives.

in his lecture he talked about the factors they were evaluating and the high voltage is important because of how it increases the rate of these reactions which clog up the surface of the anodes and reduce the ability of the cell to store charge. separate from the issue of high voltages and overcharging leading to thermal runaway.

i don't have the link anymore but it would be good for someone to post up that link so you can read it. you seem to be more than capable of understanding what he talks about and it is only a 50 minute lecture too. well worth the time imo.

his grad students went to Tesla, part of the group developing the new mixtures Tesla will use in the new battery plant with panasonic.
 
My leaf is sitting at about 55Ah after about 240 QC and 700 normal charge sessions. I'm told it's about 83% SOH (Leaf spy pro app). 23000 miles. Another leaf owner from same area is at 37000 miles and has only lost a bar just like me. I don't know what SOH you are at when you hit 10/12 bars, but imagine he is close. I've had my pack up to 50C a few times.
 
hillzofvalp said:
I've had my pack up to 50C a few times.
Click to expand...
So you want to say you managed to tweak the controller to reach 3000 A , battery side? :mrgreen:
During accelerations, of course :lol: Joke apart, I am really curious about battery longevity in those
Leaf, partly because I bought 7 modules and partly because it is a really early popular e-car, whose
owner experiences will influence future demand (silly me, advertising is everything)

have fun!
 
IceCube... WINNING :eek:

Thanks for taking the time to test, post data, start dialog.

-methods
 
I thought I'd share this reconfiguration to 15v, hoping to get these three modules wired to 45v for a 4hp scooter project.

connected "internally" with a couple lengths of 6 gauge, 4 or two would be better, but you might have more patience than me (trial and error).

plastic cover still kinda fits after cutting off the plastic boogers I made. Just need some strategically placed plastic squares where I cut the bus bars.

I didn't have a nice soldering iron so used a cheapy butane pencil torch from menards (and left the propane torch on low cuz I had to constantly relight it). The torch worked out well as I could blob on some solder while tinning, then hold the end to the tab with needle nose and heat the whole thing up, clamping it down as it melted.

Will have to run 3 more leads for bms, then will probably bolt a board on the terminals to mount it, anyway a little progress on the scooter :)
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drees said:
Long video, but worth watching. Specifically talks about the LEAF batteries along with others.

Why do Li-ion Batteries die ? and how to improve the situation?

[youtube]pxP0Cu00sZs[/youtube]
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Would any one be interested in a schematic an analog front end to do high precision battery cycling like in this video? I've been using some parts at work that should be able to get close to the precision in the video for about $100 channel + assembly. Don't have time to do the software for it though, someone else would have to pick up that portion.

Marty
 
5mo update:

I've been using my leaf battery for almost half a year now, and have driven over 1100KM on it. I've been bulk charging it in series, without a BMS this whole time, so I decided it's about time I took it out and balanced the cells. Just wanted to give an update on how that went.

AJUgNnf.jpg


I've tried to go easy on the battery and not discharge it below 54ish volts (3.4v/cell), though one time I discharged it as low as 44v (2.75v/cell).

I've been charging at 67v (at 18A using this charger, which is 4.18v per cell. When I measured the cells after a full charge my highest cell was 4.21 and my lowest was 4.14. Most were 4.17ish.

That seems pretty good I suppose. I was expecting worse, all things considered. Seems these batteries do a pretty good job of self-balancing.
 
With the capacity of these cells being so large the spread although small can amount to several AH. I would balance the pack.
 
Thanks ICE your test of the cells sole me on them, I bought a packet of 24 cells with harness and everything I need to install in my VECTRIX SCOOTER, I will use 18 cell and save the other 6 pcs. and when I get extra money I will buy 4 more and replace those (THUNDERSAGS) that I have on my TRIKE. you do good work. bye. COOPER.
 
Agreed. That's what I'm doing in the above picture. Borrowed my friend's RC charger that can handle 6S, used it to charge/balance the pack 4S at a time.

After 5mo I finally got around to putting those terminal blocks in so I can balance the cells. I balanced the battery once before installing it in my bike, but I don't have the right connector and I had to individually solder and desolder each wire to the breakout board. This way it'll be easier to balance in the future, I won't put it off 5mo again. Also when I finally get around to getting a BMS, I'll have somewhere to hook it up to.

Now that I've tapped each cell, I can finally seal up the terminals against corrosion. I did notice some connections were pretty green, so I've filled in all the gaps with gorilla glue.

YybY4Ct.jpg


That ought to keep the water out!
 
This is a tip from a pro. Dont try to charge these at 6s on an rc charger and have it try to balance it. Especially if its a cheap charger. Those cheap chargers have 2-500ma of balancing current which could mean HOURS of balancing with these cells. Just do 1 cell at a time. It will be quicker trust me.
 
icecube57 said:
This is a tip from a pro. Dont try to charge these at 6s on an rc charger and have it try to balance it. Especially if its a cheap charger. Those cheap chargers have 2-500ma of balancing current which could mean HOURS of balancing with these cells. Just do 1 cell at a time. It will be quicker trust me.
Click to expand...

Yep. I've experienced that. I've been doing them 4s at a time, and the first time I charged them it was from "shipping voltage". Before my bulk charger arrived I borrowed this same RC charger and it took 6-8 hours to charge and balance each 4S string.

This time I charged the pack up with my bulk charger to 4.18v avg per cell, then did the final charge/balance with the RC charger. Only took about 2-3hrs per 4S string.

In the end there was still a 0.01v spread. Most cells were 4.21v according to my multimeter, though one was 4.23 and a few were 4.21. I suppose I could have left it balancing longer.

Now that I have the terminals in place I'll be monitoring the voltages more often.
 
4.18V seems very high when Nissan only charges them to 4.10V (or maybe 4.11V). A 80%/long-life-mode charge only charges them to about 4.02V.

Will be interesting to see how long they last for you. How long do the cells sit fully charged before you use them?
 
If anything he may have capacity erosion but I have a feeling under our usage it will last a long time. I do believe voltage plays a significant role in longevity but I think the DOD and Current draw play a bigger role.
 
inedible what is the size of that pack ? 67v ? and how much does it weigh ? It looks big next to the hyperion, but the camera always puts 5lbs on me.
 
teslanv said:
Yes, compression is recommended for better performance.
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I don't know if that is correct. The design of these cans is made so when you put modules and clamp them using leaf hardware, cells inside do not get compressed. There are 2 plates for 8 module array, one top and one bottom. Then in between each module there is a 2-2.5mm plate with spotwelded bolt and that plate does not let module center to be compressed rather just touch each other. I got 8 of these with all the bits and bobs:
20141008_183509.jpg

20141008_183632.jpg
 
Those plates in between lets the modules snug each other a little but if you don't use them or apox. 1/8in spacers they will close that gap and maybe too compressed. I have a set of 24 and they came with all plates and top harness and I am using the spacers like nissian does.hope this helps. COOPER. :mrgreen:
 
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