cylinder vs prismatic battery cell advantages? - Endless Sphere

Recumbent Bicycle Source

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• Mar 16,

• #1

I understand the format differences, but can anyone enlighten me on the advantages vs disadvantages of each?

I read that the Prismatic can store slightly less energy for some reason. True?

vanilla ice

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• Mar 16,

• #2

Are you asking specifically about the larger life cells?

spinningmagnets

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• Mar 16,

• #3

I don't know if prismatic pouches store less energy. If yes, I'm sure they mean by weight. I believe the pouches have a smaller volume than a stack of cylinders (if same Ah) due to airspace between the cylinders. Even if they are "honeycombed" instead of inline, there is still some airspace there.

I also believe one of the problems is getting cylinders with the type of tabs that allow builders to assemble a pack with good connections. There is a thread about making a DIY $100 spot-welder, but factor in the $100 cost for a tool you may use only once, and tabbed pouches might be worth dealing with the problems that they have.

Several builders here have replaced a bad pouch in a LiPo or LiFePO4 pack. For an E-motorcycle pack, there are some cylindricals that have threaded posts (Headway?) but they are large, and it may be difficult to assemble an E-bike sized pack of sufficient voltage, and would likely have more range than you desired.

neptronix

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• Mar 16,

• #4

Advantages to cylinder cells: better cooling...

This was important for early low C cells. Like for example li-co.. which i think is happy at .. lol.. 0.5C or so.
I don't know of any lipo cells that come in cell format though. No need for it.

cylinder format also gives you some protection. But that adds weight, for sure.

John in CR

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• Mar 16,

• #5

Neptronix hit on half of the primary difference. The cylindrical cells inherently leave open space within the pack making it easier to force a cooling air flow. That open space also highlights the advantage of prismatic, because they can be packed into a smaller space. Our bikes don't need the big energy storage and energy draw of a car such as the Tesla which has thousands of cylindrical cells in its pack, so I've yet to hear of a good ebike pack with a thermal problem. That makes prismatic the hands down winning choice for ebikes.

Recumbent Bicycle Source

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• Mar 16,

• #6

I think my real question has to do mostly with choosing between the two if the price and Amp Hours are identical. Wondering if there is a disadvantage to choosing the smaller format.

I suppose cooling could be an issue, but I haven't really found anything to state such for the application in bicycles.

For Example: Weight: 36v9.5ah(9 Pounds), 36v10ah Prismatic(12 Pounds)

EBIKEKIT offers two versions of their battery which is warrantied the same but as far as I can tell uses 2 different cells Cylinder or Prismatic. Clearly there could be a weight advantage of one over the other and a slight difference in Amp Hours... but which would be the better choice.

So why would one be a better choice than the other? Both are LiFePo4.

I'm a little confused by their marketing of their batteries.

But I'm interested in them because of the convenience, package, and warranty. They seem a bit on the spendy side compared to some manufacturers I've read here. But at the same time if they really perform over the long term it could be money well spent, because I've read of failed cells on some of the cheaper batteries. I'd rather purchase one good battery with a solid warranty than 2 cheaper ones. I'm in the USA so warranty service shouldn't be a problem, unless of course there is some outrageous hazardous material fee to return the battery.

neptronix

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• Mar 16,

• #7

Yikes.
I think that is the most overpriced battery on the market.
A friend of mine locally says he only got 6ah out of his and had to return it - sounds like low quality stuff.

They literally buy it from China, and then mark it up about 75%+ after they pay shipping.
Is a warranty really worth it to you?

Recumbent Bicycle Source

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• Mar 18,

• #8

How would I know? If a battery fails at 6 months and I have to buy it 3x where is the value?

That's the whole point. Expense upfront may or may not be high? Again how would I know?

Golden Motor sells a 16ah 36v in what looks like very similar packaging for $395 and it appears to be the same weight - about 12lbs as the Ebikekit 9.6amp hour.

Link: http://www.goldenmotor.com/ click on EV Battery.

But same question applies.

All this stuff is coming out of China because no companies in USA appear to be making these Batteries due to Lithium costs and Availability or Environmental Regulations... who knows?

I'm always open to suggestions about products that stand the test of time and where they were purchased.

Thanks for replying.

BTW: Bionx is the most overpriced in my opinion.

neptronix

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• Mar 18,

• #9

That is why a lot of us go with ping batteries. They are not the best, but the support has been good, and the product seems to last a long time.

Or we go with headways ( self built packs ), A123 from cell_man, or roll our own lipo batteries with no BMS, aka manual BMS

These seem to work for us; i have nothing positive to say about these packs that all seem to come from the same place. Pay twice as much and it looks like you get the same thing but with an American warranty for 1.5 years.

You still get failures and downtime all the same, you are essentially just cutting your mean time between buying a new battery.

I would rather buy something that is ES-tested and approved with no warranty than something potentially sketchy with a warranty, even if it is an American warranty.

SniperGaulois

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• Jan 22,

• #10

Cost, it's mechanically simpler to produce cylindrical wallpaper and baking foil, same for batteries.
Strength, companies like nissan actually use strong metal cans to store and cool their prismatics, and a bike with cylinders may resist a fall better.
Cooling, cylinders provide some expansion space and some cooling. Cylinders with cap-cooling last longer than cylinders will external cooling because the cooling diffuses through all the layers of the battery.
Easier storage and manual labour costs, cylinders are difficult to short circuit due to the tabs being at opposite ends
Size flexibility, cylinders are low priced because they cover many markets, bikes, pc's, shavers, vapes.

They will perhaps do prismatic car cells that are easier than cylinders because of the size constriants, but cylinders are easy to move between robots on conveyer belts, and have 2x types of protection which may eventually have 100% short circuit protection, except for tesla which doesnt have internal battery protection afaik.

jonescg

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• Jan 22,

• #11

Cylindrical cells are cheaper and faster to produce en mass as they lend themselves to automation.
Cylindrical cells have higher energy density (Wh/l) than both pouch and prismatic, but about the same specific energy (Wh/kg).
Even with the hexagonal close-pack formation, the triangular gap between them accounts for little lost space - it will still store more energy per litre than a prismatic or pouch.
Cylindrical cells don't deform due to swelling, because of the hoop strength in the steel can (which is barely 0.2 mm thick).
Cylindrical cells can be cooled from the radial surface without creating a large temperature differential within the cell. As heat is removed from one side, the thermal conductivity around the cell's content is high enough that you don't get a big difference from one side to the other. They can also be cooled from the top and bottom axis as well, but the thermal path is longer due to material gaps.
Finally, cylindrical cells are way more consistent when they leave the assembly line. They are 18.05 mm in diameter and 65.0 mm tall with very little deviation from this. Pouch cells on the other hand can vary in thickness my as much as 0.5 mm (or about 5%) which makes any errors multiply into major headaches during pack construction.

However, cylindrical cells are small, and a PITA to assemble and terminate compared to pouch cells, and to a lesser extent prismatics. Ultrasonic wirebonding to a uniform busplate is the gold standard - but at least this can be mechanised and automates - hence Tesla can smash out thousands of Model 3 packs each day. 2.6 to 3.4 Ah per cell is pretty small, hence Tesla's decision to move towards the larger cell which is closer to 5 Ah. Fewer parts to assemble, but still in the order of cells to a pack.

Interesting read attached:

Hillhater

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• Jan 23,

• #12

...... hence Tesla can smash out thousands of Model 3 packs each day. ...... i

They hope.....but Not quite yet ..
Teslas current M3 production rate is under 700/day, and one of their main problems has been insufficient pack supply.

dogman dan

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• Jan 23,

• #13

FWIW, I don't think EBK is selling any prismatic batteries, though at times in the past they have. I used to work there.

The "Blue" pack is still cells, but without the fancy metal box. I don't know if there is an actual cell quality difference between the box and the blue, but what they pay wholesale is higher on the boxed pack. If you wanted to buy their battery, you blew it, they had a 25% off sale going for a long time at Christmas. Call and beg might work.


A lot of EBK's cost is that they sell a battery that is certified and legal to ship in the USA. Many are not. And they do have a fairly long warranty, vs a china cheap pack. And, being in the USA, if they sell a battery that burns a house down, they get to pay though insurance.


My insurance company would have loved it if they could have caught up with the china shipper that sold me a cheap battery.

Various shapes and sizes of lithium-ion batteries cater to different applications, and two contenders have been in the spotlight: prismatic and cylindrical batteries. Let’s explore these powerhouses and understand why the Prismatic Batteries might be ready to steal the show.

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Prismatic Batteries: Power in a Box

Prismatic batteries come in rigid shells with a rectangular shape, allowing them to be stacked efficiently in battery modules. There are two types of prismatic batteries: stacked and flat. Stacked prismatic batteries deliver a powerful energy burst, perfect for high-performance applications. On the other hand, flat prismatic batteries focus on energy density, providing long-lasting durability. These batteries are commonly used in energy storage systems and electric vehicles due to their larger size and capacity, making them less suitable for smaller devices such as mobile phones.

Cylindrical Batteries: Compact and Versatile

Cylindrical batteries, as their name implies, come in cylindrical casings. Their compact and rounded design enables easy fitting into devices of different sizes. One of their key benefits is their ability to prevent expansion, a common problem in batteries that leads to gas buildup inside the casing. These versatile power sources initially gained recognition in laptops and have since become widely used in electric vehicles, electric bicycles, medical equipment, and space exploration. Their ability to withstand atmospheric pressure variations makes them essential for missions like those involving Mars rovers.

Key Differences between Prismatic and Cylindrical Batteries

• Size Matters: Prismatic batteries outsize their cylindrical counterparts, holding significantly more energy. To put it into perspective, a single prismatic battery can match the energy of 20 to 100 cylindrical batteries. Cylindrical batteries, being smaller in size, are suitable for applications requiring lower power and are used in a wider range of devices.
• Fewer Connections: Prismatic batteries require fewer connections due to their larger size. This means there are fewer chances for manufacturing defects, giving them a significant advantage over cylindrical batteries.
• Energy vs. Power: Although cylindrical batteries store less energy, they deliver a more powerful performance. This is because they have more connections per ampere hour (Ah). As a result, cylindrical batteries excel in high-performance applications, while prismatic batteries are great for optimizing energy efficiency.

The Prismatic Battery Revolution

The electric vehicle industry, known for its rapid evolution, poses an intriguing question: will prismatic batteries eventually surpass cylindrical ones? Currently, cylindrical batteries dominate the sector, but several factors suggest that prismatic batteries might overthrow them.

Prismatic batteries offer cost-saving opportunities by streamlining manufacturing processes. Their larger size allows for the production of bigger batteries, reducing the number of electrical connections that need welding. Furthermore, prismatic batteries are a perfect match for lithium iron phosphate (LFP) chemistry, known for its affordability and accessibility.

Unlike other chemistries, LFP batteries use easily available materials, eliminating the need for expensive rare materials like nickel and cobalt.

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The rise of LFP prismatic cells is already evident, with Asian electric vehicle manufacturers adopting prismatic LFP batteries.

However, LFP chemistry has its limitations, including lower energy storage capacity, making it unsuitable for high-performance applications. Additionally, battery management systems may face challenges in accurately predicting charge levels.

Prismatic Batteries in Energy Storage Systems

The demand for battery packs goes beyond electric vehicles, with energy storage systems (ESS) playing a crucial role. Prismatic batteries are already preferred in ESS applications due to their longer cycle life, reduced risks, and lower costs compared to cylindrical batteries.

Tesla’s cylindrical cells have gained considerable attention for their compact design, high energy density, and cost efficiency. While prismatic batteries have not yet replaced them, Tesla’s future decisions could tip the scales.

Will Tesla transition to LFP chemistry and embrace prismatic batteries? The answer could have a significant impact on the battery landscape, especially with the rising global raw material costs.

The stage is set for an intriguing battle between prismatic and cylindrical batteries, and only time will reveal the winner in this electrifying competition.

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