New High capacity Li-Ion high cycle count

[nealsaiki]

Good comments! I wanted to clarify a few things about my battery interconnect technology.

Yes, it is correct that when you use super high energy density cells (>200 wh/kg) they run hot over 1c discharge. Tesla can do it because they have active liquid cooling. I favor passive air cooling and staying under 1c discharge. Can't fight I^2R either.

I don't have plans to make packs for electric bicycles because there is plenty of good technology out there for connecting small packs together. When you make a huge pack, it's totally different. Just working with thousands of cells can be a nightmare.

The biggest problem is thermal heating of the pack. Welded nickel tabs are fine for small packs, but copper interconnects have 4 times less resistance and they don't easily get warm when you run current through them. My technology also covers much of the ends of the cells with a conformable layer of copper for both low resistance and good thermal transfer. Tiny spot welds are not good for either thermal transfer or resistance. 1 milliohm in resistance makes a difference when it comes to thermal transfer. Big high energy density packs run hot and it's a problem that most people don't appreciate.

The main problem with EVs is that they have too little range. It's a total buzz kill to have an EV and constantly have to worry about getting stranded. The packs I design use the lowest cost/wh of any lithium battery technology (when you buy millions of cells). I wouldn't call them "massively oversized", I'd call them barely acceptable!

Ebikes are totally different. You can always pedal home. EVs need to have extra range. You don't want to have to constantly charge during the day and getting stranded is not a real option.

Neal Saiki
CEO NTS Works Inc

 

[Lock]

Hello Neal

Welcome to the Sphere. Nice to see you here.

Apart from "ebikes", think one size up, as eScooters... eg the EVTs with a 2kWh pack... Any interest in packs approx this size? I believe there'll be a huge amount of growth in this segment over the next few years.

Lock

 

[redorblack]

The other major consideration that Tesla had to deal with was safety... they've got every single cell fused on both sides, got each sheet of cells fuses and the entire pack fused... all on top of the active water cooling system. I see no mention of the safety issues involved with a bad cell in a multi-cell pack. On CandlepowerForums you can find photos of the aftermath from flashlights that became pipebombs using 18650 cells in series. What will this connection method do to deal with that?

 

[nealsaiki]

Yes, I am working on 3+kwh modules for scooters. It is going to be a huge market in the next few years.

Safety is a great question. It's the reason I'm not inclined to sell to hobbists. There are so many ways to make a safe or unsafe system.

Cells have evolved a lot since Tesla first introduced their car and now many safety features can be built into the cells. 18650 cells are very safe due to their limited cobalt content and steel housing. PTC fuses and current interrupt devices are pretty much standard, although you can certainly order whatever you want when you order in quantity. The Tesla system is geared toward high performance and so it's safety system has to be very complex. At low C rates, PTC fuses in the header of the cell are fine. My system also facilitates external PTC fuses at every cell junction on top and bottom of each cell. I also have a built in thermal fuses at both ends. These are independent of current.

Many new 18650 cells will 100% pass a nail penetration test.

Another difference is that I favor thermal contour mapping of the cell array to identify cells getting hot way before a thermal runaway. My technology facilitates extensive thermal measurement of every cell and it's all built into the walls of the pack. This technology identifies problems much earliery than fuses and gives you the ability to replace the cell before failure.

I also have technology that isolates each cell to prevent cell to cell flame propagation with a 1100 degree fireproof barrier. One cell going up in smoke is bad and stinky, but not a dangerous event.

The tricky part was doing all this an to still keep it cost effective. I've spent a huge amount of time on this, but I think the battery is really the most under-developed part of an EV.

Good questions!

 

[csm]

http://www.ntsworks.com/New_Battery.html

Anyone found any pictures and/or video of this "Breakthrough Interconnection System"?

 

[nealsaiki]

I made a little video with a summary of the technology. It still doesn't show you how it's done, but rather it explains what it can do. I have a couple of OEM manufacturers that are licensing the technology. Their products should come out next year.

[youtube]GahcFeTCZgc[/youtube]

Neal Saiki
CEO NTS Works

 

[sk8norcal]

http://www.ntsworks.com

2x4 cargobike

 

[sk8norcal]

[youtube]gb7K3uN7CWQ[/youtube]