Nissan Leaf Cells Test Data

[MitchJi]

Hi Giovanni,

Great idea on the Spyder (I want one).

It would make a very efficient EV using 24 Leaf modules in a http://www.vintagespyders.com
The ready to drive ICE version only weighs 1250lbs. It could even be better using an Alulight monocoque chassis.

An AC50 motor bolted to a Borg-Warner EV transaxle would create enough space for 24-48 a Leaf battery modules.

http://www.thunderstruck-ev.com/ac-motor-kits/ac-5x-hpevs-curtis-kit-50-51-ev.html

AC-50 w/1239-8501

$4,425.00 - 96-144V 500A 87HP at 6000RPM

Includes HPEVS motor, Curtis controller, Tyco contactor, Spyglass display, wiring harness, throttle, and custom programming.

But IMO an AC50 motor is a bad idea. It seems almost like proposing the use of ThunderCrap cells. Why would anyone use ThunderCrap cells when they can purchase Tier One oem quality Leaf modules at wrecking yard prices?

Why would anyone buy an AC50 when it's possible to buy Leaf or Tesla or Volt motors and inverters-controllers at wrecking yard prices? If those choices are not exactly what you want if you wait 6-18 month's you can probably add Chevy Spark and BMW i3 motors to the list.

 

[MitchJi]

Hi,

Did you mis-read my question?

Is it possible/easy, without taking the Modules apart, to use them as 1s,4p?

Because I asked if it is easy to use a Module as 1s (3.6v nominal) and 4p (120ah).

If trying to leave cells together, you're going to need to remove the top 1" of the can,all the way to approx 1" from the edges. Then get creative on figuring how to complete the series wiring

I want to leave the modules together, not the cells, and if I can do that all the "series wiring" would be done when connecting the modules, not the cells.

 

[Giovanni LiCalsi]

We will have wrecking yard EV parts galore in the next year.
This is a good time to build your own EV .

 

[cassschr1]

Sorry bout that, you're correct . I did mis-read it. At this point I don't remember. Try a skype with harold in CR. He should be taking his apart about now. Actually try about april 20.

 

[John in CR]

I just wanted to correct some erroneous info above. These cells are absolutely kept under compression. I have a full rack of 24 and I have 6 loose modules. Stack the 6 loose modules up and they are almost 22cm tall. The rack of 24 bolted down tight as it came out of the car measure 81.5cm, 20.4cm for each 6.

All pouch cells must be kept under some compression for different reasons, and these are no exception. If these were loose fitting in the sardine can then all kinds of bad things would happen, starting with banging around with bumps eventually eventually causing damage and fatiguing the thin aluminum going to the terminals. Then there's puffing from gas coming out of the chemical mix, which compression helps prevent.

I plan to open some of my cans, so I'll try to measure how snug they are in the can, since much of the measured change in thickness is probably the can being pushed snug to the stack of cells. The metal spacers at the ends between each module are in a recessed area and are obviously there to more evenly spread the compressive force of bolting at the corners across the width between the bolts. Anyone who plans to keep the cells in their cans will need to use something for spacers, which are 3.7mm thick. I may end up using a rack of 20 cans, but I'll use some lighter materials to replace the steel spacers and end plates, whose weight adds up quickly.

 

[Hillhater]

I just wanted to correct some erroneous info above. These cells are absolutely kept under compression. I have a full rack of 24 and I have 6 loose modules. Stack the 6 loose modules up and they are almost 22cm tall. The rack of 24 bolted down tight as it came out of the car measure 81.5cm, 20.4cm for each 6.

John, yes i can see how the picture posted earlier could be miss leading.
Whilst it appears that the "corner frames" are taking the clamping load, that may not be the full picture depending on the profile of the bottom of the "can" which could still contact the top face of the "Can" below.

Here you can clearly see how the pouches are not in compression and how the internal module corner frames protect the pouches.

 

[John in CR]

The clamping load of the 4 long bolts going thru all 24 modules is spread across the 8.5" width by the metal spacers which have holes for the bolts to go thru. The bolts squeeze the modules down more than gravity does with a stack of 6 such that a clamped 6 is almost 1.5cm shorter. That's well over 5cm (over 2") shorter for a rack of 24. The recess at the ends fully offsets the spacers, which I hesitate to even call spacers, since the stack of 6 is exactly the same height with or without them.

The cutaway picture is misleading with respect to compression, because they made the long cut at the raised edge of the center recess. There isn't space between the cell and rectangular center of the can like that shadow would lead you to believe. Simply pushing down on the center of module shows that there's no space between the face of the cell and the can.

When the clamping pressure is applied, I'm not saying the cells are squeezed thinner. It simply loads the springs designed into the shape of the top and bottom faces of the cans in a way that applies pressure to the cells especially over much of the center area.

 

[John in CR]

Those who worry about sag so much simply don't have fast enough bikes. My primary bike gets almost 20V of sag when I twist and hold WOT, and it doesn't affect my riding in the least regardless of SOC. Someone would never have a car where they ride around with the pedal to the floor at all times like a golf cart, and motorcycles are the same. Why anyone would accept such pitiful performance on their ebike baffles me.

I want to go whatever speed I want for the road and traffic conditions, not ride around at some barely acceptable speed under optimum conditions only to be slowed by the smallest headwind or slightest grade.

When you have acceptable performance, ie you ride around at partial throttle, then voltage sag doesn't matter. If the cause of the sag generates enough heat that your batteries are getting quite warm all the time, then yes that matters. If a string of 48 of these modules can push a car with passengers weighing well over 3,500lbs and last for years, then there's no doubt that a string of 10 can do justice for less than 500lbs of motorcycle and rider, or 5 can serve 300-350lbs of bicycle with rider. A 20 module pack should be able to handle both high performance and long range.

 

[Punx0r]

Interesting info John

It seems each can wants approx. 50mm/24 = 2mm of compression per can?

The only thing that seems a little odd is where they've pressed the centre area of the can. This would seem to result in an uneven surface pressing into the only part of the face of the cell. Perhaps this is intentional for some reason?

 

[John in CR]

The only thing that seems a little odd is where they've pressed the centre area of the can. This would seem to result in an uneven surface pressing into the only part of the face of the cell. Perhaps this is intentional for some reason?

Mine aren't like the cutaway can. Both front and back have a large rounded corner rectangle that touches the center of the cell first. The transition of that indention is spread over about an inch before you get to the next bend in the surface, so once compressed the spring action is gentle with a smooth flat contact with the cell. The can in that cutaway pic would create dents and ridges in the cell while under compression. I've got some software issue in my computer or I'd just shoot a pic that would explain it better.

 

[Punx0r]

Thanks, that explains it nicely.

 

[Harold in CR]

Actually, that indent doesn't matter all that much, for compression.
My modules are swelled. Both sides have the same indent pattern. ONE side of my 3 are swelled.




I cut my first can open at the connection end and rolled back the tabs that were cut.
Then I cut down one side UNDER the rolled edge, so I could, if needed, just reinsert the cells and tape the can with Packing tape with fiber strands. Once that was done, it was easy to slide a stick of wood between the can and the blue separator to free the cells from the can. Then, pulled the 4 cell pack out of the can.



Once the can END was opened and the tabs rolled back,I removed the plastic protector cap. BE AWARE, this is a thin cap and it IS possible to make contact with the tap and the side of the can, once removed. Maybe short from the cells to the can is possible. I was careful, so, no drama to report.



In this photo,I tried to make yellow colored "V"'s where I then cut the taps to make all the cells individual, so, 4S1P is easily possible. I used a dremel type tool with cutting disc. Same tool I opened the can with. Then, I cut the taps mostly in 2 pieces, then, used my Crimping tool with cutting jaws to complete the cut. No drama here, either. Just pay attention. Once I decide where to use these cells, I will cut the bent part from each tab, so they are flat, and easy to solder or clamp to for connection in series.



Hope this info is useful to someone.

 

[John in CR]

None of the modules in my crate are puffed at all. Did the 2 of mine that came in your crate also swell? I'm sure Ed would have noticed that swelling, so my guess is that your crate spent too much time in the tropical sun. My HK packs that were in your crate are fine. I think you'll want to pull them out of the can in hope that it's just one cell swelling.

My gut reaction would be to drain them down to 3V, get them good and cold, apply compression and see what happens. I had 2 HK hardpacks swell just enough to pop the case open, and I put them in a pack using LFP's electrical tape compression, that is still fine 2 years later.

 

[parabellum]

My gut reaction would be to drain them down to 3V, get them good and cold, apply compression and see what happens. I had 2 HK hardpacks swell just enough to pop the case open, and I put them in a pack using LFP's electrical tape compression, that is still fine 2 years later.

John. Please, describe in more details LFP's electrical tape compression method.
Thank you guys about all data on Leaf cells.

 

[John in CR]

My gut reaction would be to drain them down to 3V, get them good and cold, apply compression and see what happens. I had 2 HK hardpacks swell just enough to pop the case open, and I put them in a pack using LFP's electrical tape compression, that is still fine 2 years later.

John. Please, describe in more details LFP's electrical tape compression method.
Thank you guys about all data on Leaf cells.

Electrical tape is elastic, so the idea is to stretch it some on each turn of a multi-layer wrap to apply pressure to compress strings of RC lipo. Support at the corners to avoid deforming the end cells is important, and is a failure of typical RC lipo packs, since the shrink wrap deforms them. In the past I saved all my hard pack cases and used one of the case bottoms on each end of my 20s strings, and those sharp plastic corners withstand the compression of the electrical tape. Don't try to stretch the tape too much, and try to be consistent in the force, because it's quite easy to apply too much or uneven pressure turning a rectangular stack of cells into a trapezoid.

I will be processing some packs today and will take pics. I don't have enough hard cases, and they're a bit short for these cells anyway, so I need to come up with something new for corner support. Worst case I'll use some 1mm aluminum sheet to make channels to fit the cells if I can't find something better.

 

[parabellum]

Good idea, because I found my fiberglass reinforced tape will brake fibers on hard case packs corners over time and poliprop tape part will stretch from there with no return. Makes sense, electrical tape is vinyl and has kind of memory, trying to come back to original shape. Thanks, pictures highly appreciated.

 

[Harold in CR]

John, 1 of your modules I have is slightly swelled. The other is not, at all swelled. I think it's normal for any modules that are out of the 24 piece packs. As best as I can tell, mine are all pretty much the same thickness, just slightly swelled, overall.

 

[teslanv]

Quick calculation of the cost/wh and lifetime cost based on estimated cycle life of 500 cycles, shows the Leaf cells beat Ping LiFePO4 and HK LiPo hands down.

 

[mvly]

Quick calculation of the cost/wh and lifetime cost based on estimated cycle life of 500 cycles, shows the Leaf cells beat Ping LiFePO4 and HK LiPo hands down.

This is what I have been preaching all along after my fiasco with HobbyKing batteries purchase. The only catch is these are big and heavy. But if you are going with anything over 20AH these are far cheaper and safer than those HobbyKing assuming you are not trying to build a super motorcycle with high current draw.

And the estimate cycle life is a bit low. True they might be for used cells, but for me after 100 cycles, the cells are just as good as the day I got them. So I would put 800 cycles for the expected cell life.

 

[teslanv]

I noticed the batteries hybrid auto center is selling are new 2012 batteries, so perhaps they would be good for ~1000 charge cycles. Looking better all the time. Just wish it was easier to configure them into 4S1P without tearing open the sardine cans.

 

[teslanv]

I am correct in thinking the center screw terminal on these cells is for tapping a balance lead? (i.e. if you probe the Black & Center terminals or the Red & Center terminals you get a 1S Voltage?)

 

[parabellum]

I am correct in thinking the center screw terminal on these cells is for tapping a balance lead? (i.e. if you probe the Black & Center terminals or the Red & Center terminals you get a 1S Voltage?)

Yep.

 

[cassschr1]

John in Costa Rica.. Did you figure out how to make a them into 4s inside the can?
Actually I meant Harold in c r.

 

[MN Driver]

John in Costa Rica.. Did you figure out how to make a them into 4s inside the can?

This thread, scroll to April 9th, January 28th, and August 2nd.

 

[cassschr1]

thank you MN driver.