Nissan Leaf Cells Test Data

[Hillhater]

Thanks for that ...(How do you find the time to watch all those shows ?? :lol: )
Very impressive and much better than previous CALB cells, they really on par with lipo for performance and not far behind on density now. ..with a much longer life expectancy !
Have you seen any tests yet for the 25Ahr, 20 C cells that he mentioned ?

 

[MN Driver]

Thanks for that ...(How do you find the time to watch all those shows ?? :lol: )
Very impressive and much better than previous CALB cells, they really on par with lipo for performance and not far behind on density now. ..with a much longer life expectancy !
Have you seen any tests yet for the 25Ahr, 20 C cells that he mentioned ?

I'm interested in electric vehicles and although some of it is just a bunch of chat, there's good bits here and there. I usually extract the video from Youtube and use VLC player and watch it at a speed of 2x or 3x and even at 3x I can make out what Jack is saying quite well because he talks slow. I also often skip the parts where they are talking about a specific car conversion unless they are talking about something EV specific that I might want to use with my conversion. I usually manage to watch the 1.5-2 hour shows in 30-45 minutes. I've watched every single one of them.
No results yet on the 20C cells, I'm not sure if they have shipped to anyone yet and the manufacturer spec sheets don't really say much but we'll eventually get some independent test somewhere.

The blue CALB cells were not nearly as nice as the CA series gray cells but the new CAM series is looking really good.
Here's a video of a 180Ah gray cell at 12C ambient temperature getting a solid 12C draw in a less controlled manner, ahem, shorted through a wrench in a bucket of water. The 40Ah cells sag less at the same C rates and starting at a normal room temperature ambient helps quite a bit too. ...granted 12C is going to heat them up to room temp in short order anyway.
https://www.youtube.com/watch?v=lyYfFeWwd9I

I'm getting a bit off topic about the Nissan Leaf cell testing so I'll leave it at that. Feel free to PM me if you'd like, although I'm sure the 20Ah cells will eventually be cause for a new thread here since 25Ah 20C cells would be ideal for many ebike conversions.

 

[Hillhater]

Yes, i had seen the "Irish discharge" test procedure before ! :lol:
Its probably worth starting a thread to alert folks to these new CAM cells..especially if the 20C become available..as im sure many Ebikers/ EV'rs still ignor the larger prismatics due to their history of sag and size !

 

[heathyoung]

HOLY ISHT! 2000A and it sagged to 2.3V!

The thundersags were OK but at high discharge rates they sag badly. 12C on a thundersky would likely result in 0V per cell

That's changed my mind about importing some of those leaf modules - the size is right, but the price... with postage... hrmmm....

 

[hillzofvalp]

I live pretty close to the Smyrna battery plant.. But it's very difficult to get through to the people who are in charge of the b grade cells

 

[mvly]

Just posting this for an important update on my LEAF pack.

Just as refresher, I have my 6 modified 2s2p to 4s1p packs in a 24s1p configuration. I run it as a 24s1p but balance charge as a 12s2p because of the limitation on my Hyperion 1420i charger. They very balance after each discharge.

They have around 150 charge/discharge cycle by now.

A couple of days ago, I was running my pack pretty hard. I usually ride around 1C-1.5C. But during that day, I was maintaining 4-5KW power usage meaning it was running pretty much at 2C most of the ride. When I went to charge it, I notice 2 cells' voltage were funky. Keep in mind this is after I paralleled them to charge. One was about 0.2V higher than the average and one was about 0.2V lower than the average. A total of 0.4V spread.

I continued to charged it and the one cell that was 0.2V higher than the average hit 4.18V much earlier than the average. (I set the charger to stop charging at 4.18V and start balancing the other cells) The other cells at that point were around 4.12V each. The balancing was taking forever so I rode into work without fully balancing the pack. Again I balanced charged it and this time the same cell hit 4.18V before the other cells. But this time the other cells were 4.13V. Again I left it to balance for quite a while. When I got home, I balance charged again. This time when the high voltage cell hit 4.18V, the other cells were around 4.15V. I left it balancing for another good 1-2 hours. At this point, the 0.2V lower than average cell pretty much behaved like the other average voltage cells.

Today when I went in to work, I balance charged again. This time, when higher voltage cell hit 4.18V, the other cells were at 4.16V. So it looks like it's getting better, but it is weird such phenomenon happened.

So long story short, I think I have a weak cell, but it might be recovering. So after around 150 charge cycle, the leaf pack seems to show some weakness. Keep in mind this was a used battery pack to begin with so I don't know how many cycles these cells have gone through before I got them. The other packs seems to be doing fine, but they do sag more compared to when I first got them. They still seem to give the full 25Ah.

If the high voltage cell is indeed bad, I might have to convert my pack to a 22s1p and balance charge as a 11s2p battery pack.

I will keep you guys updated. This might be the first documentation of this pack going bad.

 

[zEEz]

I will keep you guys updated. This might be the first documentation of this pack going bad.

I hope it will be ok, but you definitely convinced me to keep the modules stock 2s2p for my e- conversion,
to avoid stress. Probably 50 amp continuous is too much for a single cell, in your case.
In the end on a Leaf the peak is around 200 amp on 2p , but on a car the average power used is
probably often well below that level.

have fun!

 

[mvly]

OK I figured out what is wrong with the pack. I think this problem existed way before i notice. It was masked because I parallel them when charging. Here is what I know:

1) After a full charge and removing the connector when converting the 12s2p to 24s1p, I do notice a small spark noise if I don't pull the parallel connector out smoothly. This means that during the connects and disconnects, a fews cells are charging and discharging into each other, hence the sparking noise.

2) One cell is always at 4.13V when fully charged. The other is always at 4.18V when fully charged. The other cells are around 4.16-4.17V.

3) This problem is only showing up on one set of the battery. Namely the one I put together first.

4) All the cells are balanced when I end my ride after 14-15Ah of usage at 1-1.5C current draw. i.e. the imbalance cells are balanced after bringing them to a lower voltage.

Here is my conclusion:

1) I have 2 weak or funky cells in one of the battery set.

2) However they are only imbalance when fully charged.

3) This does not seem to affect their self discharge rate or their overall battery set voltage. The 2 sets of battery sees similar overall voltage after a few hours of sitting idle.

4) They seem to balance themselves out throughout the ride and seem to still give me the full 25Ah I got before. I will need to do the full discharge test one of these days.

I will keep an eye out for them in the long run, but I think this problem might not be as bad as it seem. Still there is something funky going on with those 2 cells.

I anticipate to change the pack to 22s in the near future by cutting the 2 funky cells out of the series and rewiring the pack to be 2 packs of 11s1p. Luckily the 2 imperfect cells are in series next to each other so I can easily cut them out without doing too much rewiring. In the meantime, I will continue to use them as before. I have recently gone solar so I don't let pack go below 3.8V per cell.

 

[Deanwvu]

How are the LEAF batteries in terms of long-term storage?

If I only use a LEAF pack a few times a year for long-distance bikepacking, presuming I keep the pack at the recommended storage voltage, will it last a long time?

Is that a bad idea as a use case for this battery? Do they perform better and/or last longer if they are used regularly?

 

[Arlo1]

Check this out a whole pack for $5500 new http://insideevs.com/breaking-nissan-prices-leaf-battery-replacement-5499-new-packs-heat-durable/

 

[Punx0r]

I imagine that's below cost price as they're clearly restricting sales to by insisting you trade in your old battery (and I suspect the swap must be done by a Nissan dealer).

 

[mvly]

How are the LEAF batteries in terms of long-term storage?

If I only use a LEAF pack a few times a year for long-distance bikepacking, presuming I keep the pack at the recommended storage voltage, will it last a long time?

Is that a bad idea as a use case for this battery? Do they perform better and/or last longer if they are used regularly?

I think the best you can do is during those non-use time, I would keep them at storage voltage which is around 3.9-3.95V per cell and keep it in refrigerated temperature. NOT freezing but cool temperature. I make the analogy of Lithium battery to food. The food will eventually go bad. So you try to keep it cool and the right mixture. Never too concentrated at either end.

As for how long it last, I do not know. But Nissan is willing to back it up for 8 years. I don't know if they will last longer if use them regularly. I think the point to maximizing Lithium battery life is to maximizing the time it's in storage mode and minimizing discharge or charging current. So I still think your best bet is to store and don't use it a much.

 

[Deanwvu]

Mvly,

When you say storage temperature, do you have a degree range in mind?? I have a refrigerator downstairs that could be purpose set to the ideal temp....

 

[mvly]

Mvly,

When you say storage temperature, do you have a degree range in mind?? I have a refrigerator downstairs that could be purpose set to the ideal temp....

I am in no way an expert on this, but the consciences on this subject is to keep it below room temperature (25 degree Celsius) but higher than freezing (0 degree Celsius). My guess would be to keep it around 15 degree Celsius at storage voltage for prolong period of non-use. Others might want to chime in, but that is what I would do for my Lithium batteries.

Good luck!

As for an update on my pack. Everything seems normal again for my 24s1p pack. Again to reiterate, the pack sags a bit more than when I got it. But it is still very manageable. Moreover, I have gone solar recently so I try to charge both ways. Therefore these cells are at around 1/2 to 1/3 capacity when I end my ride. The other thing I would like to note is I still am getting at least 25Ah out of these cells. Last time I rode my bike and forgot to bring my charging cable with me. I had to ride home at 1/2 capacity. I ended up using a little more than 25Ah before the cells were averaging 3.45V per cell. The cells were imbalance at that point. Some were as low as 3.3V and others were still at 3.5V. But nothing troubling. They balance up super well!

I have hit the first major milestone: 150 cycles

I am looking for milestone 2 which I have set at 300 cycles.

Then milestone 3 which is at 450 cycles and if I am lucky, milestone 4 which is set by me at 600 cycles! We will see how long these Leaf Cell last!

 

[John in CR]

mvly, do you keep your cells under compression, and if so how are you applying the compression force?

 

[mvly]

mvly, do you keep your cells under compression, and if so how are you applying the compression force?

I am not applying any force at all. I do keepisode the pack together though.

 

[John in CR]

mvly, do you keep your cells under compression, and if so how are you applying the compression force?

I am not applying any force at all. I do keepisode the pack together though.

Expect a relatively short life then. Nissan goes to a lot of trouble applying an even force of compression across the face of the cells. I have a full 24 module rack plus 6 loose modules. I keep the 6 stacked with gravity as the compression force, and the rack of 24 is compressed to be over 2.5" shorter than 4 times the stack of 6 compressed by gravity. Icecube demonstrated a significant capacity increase with cells under compression, and I'm not sure that was even spec compression.

I'd guess that your cells aren't laying horizontal, so without a good force of compression gravity and vibration will combine to make the putty-like substance between the many layers of the cells slouch.

The cells may need only a few psi of compression force, but over that 8"x9" face of the main body of a cell, that's hundreds of pound of force. Figuring out how to apply compression to my cells is one of the main reasons I don't have mine in service yet, because the heavy steel rack Nissan uses is over the top for me.

I've had great luck using electrical tape to compress RC Lipo cells using something rigid at the corners to avoid deformation, but applying even pressure over the 8" minimum width of the Leaf cells is a different animal.

The best idea I've come up with is to make bowed fiberglass rectangles to form a flat spring. It's going to take some experimentation, but if I come up with something that works, I'll make a bunch of them since I'll already have a mold.

 

[mvly]

mvly, do you keep your cells under compression, and if so how are you applying the compression force?

I am not applying any force at all. I do keepisode the pack together though.

Expect a relatively short life then. Nissan goes to a lot of trouble applying an even force of compression across the face of the cells. I have a full 24 module rack plus 6 loose modules. I keep the 6 stacked with gravity as the compression force, and the rack of 24 is compressed to be over 2.5" shorter than 4 times the stack of 6 compressed by gravity. Icecube demonstrated a significant capacity increase with cells under compression, and I'm not sure that was even spec compression.

I'd guess that your cells aren't laying horizontal, so without a good force of compression gravity and vibration will combine to make the putty-like substance between the many layers of the cells slouch.

The cells may need only a few psi of compression force, but over that 8"x9" face of the main body of a cell, that's hundreds of pound of force. Figuring out how to apply compression to my cells is one of the main reasons I don't have mine in service yet, because the heavy steel rack Nissan uses is over the top for me.

I've had great luck using electrical tape to compress RC Lipo cells using something rigid at the corners to avoid deformation, but applying even pressure over the 8" minimum width of the Leaf cells is a different animal.

The best idea I've come up with is to make bowed fiberglass rectangles to form a flat spring. It's going to take some experimentation, but if I come up with something that works, I'll make a bunch of them since I'll already have a mold.

I was thinking of ways to apply compression. Maybe this is why I only get 25Ah as oppose to the 30Ah , but I was too lazy to get around doing it. I think the easiest way is to get a aluminum plate area sized larger than the cells and have it as a washer screw solution where you screw the four corners and you will be set. I might do it down the road when my pack gets worst, but for now they are still pretty decent. 150 cycles so far without major degradation besides the sagging. Keep in mind I kept the pack the way it was. I did not split them or what not. So it is in packs of 4 cells. The wiring is what I did to transform it to 4s1p. I think this might be helping the battery too. Less sliding and vibration because you have more mass to acceleration.

 

[Harold in CR]

After making my cells into 5S1P, they would only slide partway back into the aluminum cans. I have them all weighted with large (31Series) Lead batteries. They are well compressed, while I await the crate with my 100cc Kawasaki Forks and other goodies to arrive, around the 10th of July, or so.

The frame I built may not perform as well as a manufactured frame, but, it will be my first attempt to travel these hills for 21 miles and carry groceries back and up the 3Km long hill to the house.

I have a pretty slick way to compress the cells using a spring leaf that will be cut into 2 pieces, center hole drilled, and through bolted through the frame center support panel and pressure applied to HARD wood panels under the spring leaf. Tighten the snot out of the through bolt and check often. I have over a half mile ride to the blacktop from my house, over some damn rocky terrain. Rocks are broken/crushed and some up to football sized, all on an incline. I was afraid of fork failure, so, this other fork WITH brake set up, for the Moped front wheel, will be the finishing touch for the first ride.

BE AWARE, the electrolyte is toxic to animals. Had a damn pack rat get up onto my workbench, eat or stole a Coral Snake skin that I had NEARLY preserved, and, bit a hole in the edge of 2 Leaf cells. Had to buy another module. Used 5 minute epoxy on the holes, but, air bubbles kept sneaking out, so, there is now 4 layers of epoxy plugging the holes. Those cells will be part of my green house battery system, with SLIGHT compression.

Found that little bastard 2 days later deader n shit.

Life's a bitch, here in the jungle

 

[John in CR]

Harold,
Be careful not to have too much force of compression. "Tighten the snot out of it" sounds like too much. I can't believe no one has tried some kind of air bladder for compression, which is the easiest way to get an adjustable even force, and know exactly how much force is applied.

mvly,
Yes it's hurting capacity, but the issue is more than that. Odds are that you have the cells vertical, not horizontal. Without compression they're sure to change shape just from the force of gravity.

 

[Harold in CR]

John, the "tighten the snot out of it", is in the same category of " hand to measure the heat" on the motors. :lol: :lol:

I'm waiting for that module and forks and drum brake assembly to get here, so I can get this thing running. I will put up a couple photos of the battery set up, when I get to mounting them. Right now, the whole bike is up on the workbench, 32" off the flor. Don't need to mount batteries, then, try to get it TO the floor. :lol:

 

[MitchJi]

Hi,

yopappamon scored a Volt pack:
http://endless-sphere.com/forums/viewtopic.php?f=34&t=60460&p=915109#p914753

I'm not sure how he found it originally, but it ended up on ebay before we had a chance to close a deal. $1,400 plus $360 freight. Still over a grand cheaper than new lead.

Wonderful ! That's an excellent price ! About $3k less than Nissan Leaf modules (about 1/3rd the price)! Thank you! Time to google the Volt pack specs and to start looking for a used Volt pack!

I'm hoping between my self (industrial controls engineer) and my brother (retired Delphi Automotive electronics engineer) we can reverse engineer the CAN interface to the battery manager.

The best bang for the buck in large format lithium cells (30 Ah) are used Nissan Leaf modules (2s2p -7.2v nominal, 60 Ah) available for about $140 shipped. Check the links in my signature for more information.

I hope you start a dedicated thread on the Volt pack and convince me to change my signature!

 

[mvly]

Hi,

yopappamon scored a Volt pack:
http://endless-sphere.com/forums/viewtopic.php?f=34&t=60460&p=915109#p914753

I'm not sure how he found it originally, but it ended up on ebay before we had a chance to close a deal. $1,400 plus $360 freight. Still over a grand cheaper than new lead.

Wonderful ! That's an excellent price ! About $3k less than Nissan Leaf modules (about 1/3rd the price)! Thank you! Time to google the Volt pack specs and to start looking for a used Volt pack!

I'm hoping between my self (industrial controls engineer) and my brother (retired Delphi Automotive electronics engineer) we can reverse engineer the CAN interface to the battery manager.

The best bang for the buck in large format lithium cells (30 Ah) are used Nissan Leaf modules (2s2p -7.2v nominal, 60 Ah) available for about $140 shipped. Check the links in my signature for more information.

I hope you start a dedicated thread on the Volt pack and convince me to change my signature!

Chevy Volt is 16KWh I believe. 16KWh/$1400 = 11.429Wh/$ which is pretty good.

For comparison, I got my 2.5KWh/$600 = 4.167Wh/$

The only thing that would deter me from the Volt pack is how many cycles and if there are any damage. But base on the controller, it seems the controller operates the cells with very tight tolerance so even with high charge cycles it should still be decent! Also the format might be an issue. They claim 288 cells. So there will be more soldering and such.

Looking forward to the comparisons!

I think it took the car companies with deep pockets to finally jump start the battery industry. Before it was just the laptop/cellphone market which are big, but they can tolerate less wh/$ because they are after size and weight. While cars requires energy density and power.

 

[John in CR]

John, the "tighten the snot out of it", is in the same category of " hand to measure the heat" on the motors. :lol: :lol:

Not even close to the same league. While people were putting temp sensors in motors and having heat failures, my hand test kept me from any heat failures at all, and I'm fatter with steeper mountains to climb. OTOH I've been able to easily apply an unbalanced compression force with el cheapo thin electrical tape, so cranking down with nuts and bolts will be easy to overdo...way overdo and end up popping a cell not meant for pressures nuts and bolts can apply.

Here's an idea for you though. Take your end plates and bolts structure and put it between a rigid metal structure. Then put a car/truck inner tube on each end and pump them up to 5psi or force on your end caps. At that point just tighten you nut down snug instead of "tightening the snot out of them" and as long as your end caps are properly rigid (the hardest part IMO) then you should have the issue solved.

 

[Deanwvu]

TOXIC?????!!


I would greatly appreciate advice RIGHT AWAY, for the the health of me and my family.

I received a pack of 32 of these Leaf cells today in the mail. They came in two boxes of 16.

One box was in good condition and the battery pack inside is intact and tests great on the multimeter.

The other box was damaged heavily, from apparent mishandling by USPS.

The 16 cells in this box are partially damaged. I could smell a strange, sweet odor coming from the box. That odor was magnified greatly when I popped open the box, and there was an oily residue on much of the packing material inside the box.

I immediately put on gloves for the remainder of the inspection.

Long story short, one or more of these cells is breached and leaking an oily substance with an odd sweet odor. There are some good cells in this pack. The pack is taped and maybe glued together (the 16 cells), and the damage (the leak) is somewhere in the middle. With the voltmeter, I was able to test the first 7 or so cells and the last 5 or so, and all but one of those seem just fine.

Is this material--the oily substance leaking from the batteries--TOXIC???. I worry that further contact with this pack is dangerous--both contact and by inhaling the aerosolized material.

If it is safe, I'd like to continue disassembling this pack to see which cells are dead and which are OK. Any idea what I should use to clean these cells off?

Thank you all!