21700 battery cost vs 18650?

MinnBobber

Active Member
As 21700 battery packs come to E bikes, will they be more or less expensive than 18650 packs? …For same watt hour capacity .

Battery costs continue to decrease but will there be an initial up charge for 21700?

What companies have 21700 batteries in the pipeline?
I believe Stromer will such in 2022.
Any others?
 
The Chinese started producing the 21700 cell in 2017. I reviewed a Liito Kala pack with 21700 cells in the Spring, on this site. It was 13 ah and around $100. The same basic pack is on Ebay now for $230, something like that. It's not a brand you can embrace. But I have 100 cycles on the pack and it has held up.

Ideally, people who are dedicated to ebikes should make their own packs and encourage US vendors to supply good cells. I'd say right now that Battery Hookup, Jag 35, and Sriko are at least getting it right some of the time. If you are waiting for US ebike companies to embrace what is now a 5 year old cell? Like, why?

It's impossible to reconcile what the Chinese are doing (mostly bad, now) with what the US ebike companies are doing (very low energy stuff) and come away with a sense of a brighter tomorrow. I was looking at the Bafang pricing on packs, and they've joined US companies in making them a profit center.
 
As 21700 battery packs come to E bikes, will they be more or less expensive than 18650 packs? …For same watt hour capacity .

Battery costs continue to decrease but will there be an initial up charge for 21700?

What companies have 21700 batteries in the pipeline?
I believe Stromer will such in 2022.
Any others?

No, there are good and crappy cells both in 18650 and 21700 formats. It is not just about the cells, but the way the pack is built, the BMS, temperature control, welding method, the ports, fuse, etc.
The up charge depends on all of those factors.
We have a very decent pack with 21700 cells.
One of the reasons we delayed production of the Shakti model - we wanted to offer a long life pack and decent performance that we could guarantee the pack for 3 years.
 
I paid $600 for a Hailong style case 15ah 52v 21700 4900mah cell battery over 3 yrs. ago. Since then I have gotten a 48v 17.5ah one with the LiShen cells for $400 and a 48v 13ah one with 5000mah cells both in Hailong style cases. What I found was that they are very competitively priced to the 18650 cell batteries of the same style.

Pleased with their performance especially at lower voltages approaching the LVC comparitively. My new bike came with a 18650 cell battery and looking to make a 21700 to fit it when I can.
 
Grin Technologies (ebikes.ca) has been selling 21700 based batteries for a few years now. I've been using a 52v 14.5amp model ($750 USD now) for over a year. They've also been selling the same setup but in 10s configurations (36v - over $500 USD).
 
Alarmed by the string of E-bike fires in NYC.
The officials are now going to mandate UL certification for batteries to be used in E-bike fleets in NYC. I think this is already in the works and will go into legislation soon.
For those batteries that are not UL certified and do not have proper testing certifications, there would be some heavy legal complications if the battery has a fire issue down the road.
So, I urge everyone to consider the overall safety, not just some brand cells.
Do not be enticed by low prices and if you are putting a lot of miles on E-bikes, this is especially important.
 
Alarmed by the string of E-bike fires in NYC.
The officials are now going to mandate UL certification for batteries to be used in E-bike fleets in NYC. I think this is already in the works and will go into legislation soon.
For those batteries that are not UL certified and do not have proper testing certifications, there would be some heavy legal complications if the battery has a fire issue down the road.
So, I urge everyone to consider the overall safety, not just some brand cells.
Do not be enticed by low prices and if you are putting a lot of miles on E-bikes, this is especially important.
The only ebike I've run across that advertises, even boasts, of UL certification is Ecotric. This a very low price Chinese ebike company, so if you think UL certification is a big deal, you may be deluding yourself. I think they offered a UL and a non-UL and it was maybe $25 difference.

It's just the endless war on DIY. Nothing you say is clarified. You don't recognize that LFP is safer, and if you use a safer cell, you don't necessarily need the same certification. The cells you are talking about cannot be made safe. That's clear. Certain things happen, the cell is prone to bad outcomes. You need to fix the cells so they don't explode. You need to fix the cells so they don't explode. You need to stop blaming DIY and pretending you can actually grade these issues and assess LFP versus your messed up chemistries. Basically, you are bragging about what a great lifeboat you have. The trick is to get to where you don't need the lifeboat quite so much. You think in marketing slogans.

I don't live in NYC. Why should they dictate what I have to do? Why say I will encounter legal problems if I don't do what you say? It is the Endless Fear. That's about all you guys have left. You can't or won't point to the bad packs. It's like Joe McCarthy with his list of Communists and Homosexuals. It's all about fear. It's a weak industry with few new ideas.

Even Bafang is now part of the ebike pack cartel, and you seem to be their apologist. You raise real issues, but they are half issues strung together with meaningless certifications like UL. I'm glad Ecotric is part of the NYC revolution.
 
As a battery scientist, it is my responsibility to make people aware of the safety implications.
There are huge safety risks when you have untested packs. You don't notice it right away but when it happens, it is usually petty bad.
When you run 5V cellphone battery vs a 50+V E-bike battery, appropriate caution needs to be exercised.

@George S. , If I wanted, I could make a lot more snarky, sharp personal attacks on you but I will refrain from that.
Not sure where you got the idea I was trying to attack DIY.
UL certification at the component level is different and then there is UL 2849 for complete systems. I am yet to see ECOTRIC's certification document anywhere.
There was a discussion on that: https://electricbikereview.com/forums/threads/ul-2849-certified.12780/

Panasonic was one of the early ones to certify their entire E-bike system: https://www.ul.com/services/e-bikes-certification-ul-2849
Bosch components are UL certified and UL is not the only agency, there are many other ones too.

GM is spending 2 Billion to mitigate fire risks in their Bolt model.
In the Automotive industry, standards are much higher than what we see in the E-bike industry.
Now, if the E-bike battery catches fire, it is tough to catch hold of some Chinese companies. It is these bad practices that have led to the wild west kind of situation.

As more companies struggle to entice customers, it is important for customers to be aware of safety implications.
 
What I found was that they are very competitively priced to the 18650 cell batteries of the same style.
Yup! Same here. But blather like some of the posts here complaining about old design cells crack me up. A safe and sane pack using known reliable cells, regardless of release date. for my 36V 20a and 48v 25a eBike builds work just fine.
Promotion of home built packs is more blather and potentially a disaster. Been there done that. All builds tools some new for sale.
 

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Tom, those bare-assed 18650 cells laying around on your work bench are scary, or were you using clear shrink wrap?

I think I understand what makes a safer battery, or at least what I want to see. Cell separators. Individual fuses. Machine cut electrodes, Use of the less volatile li-ion chemistries, like NCR which will pass the UL puncture/crush tests.

Yhe cheapo hoverboard packs I bought four years ago have none of the above, but they're all finally worn out. They're still good to 50%, but then they sag to LVC and shut off. Good riddance.
 
I think ebikes are in the Bubble stage, but with all the money people are imagining they are making on their houses, it will continue. I’m going to sell my house and live in a box, but I haven’t found the box I want yet.

I think that ebikes will go back to a better mix of manufactured and DIY. I particularly think that ebike companies have done a swell job of making non-standard ebike packs off limits. And those companies are not competing. Prices are very similar from company to company. You have to consider this cell from Optimum Nano. The company is substantial, and it was in trouble a few years ago. It’s Chinese and the cell is LFP. At $2.70 for a 6 AH cell, you can get a lot of watt hours for a small amount of money. You need 16 in series to make a 48 volt pack, but the voltage is higher than that. If you take two sets of 16, so 2p16s, you have have 32 cells. The cost for the cells is about $86, but there is tax and shipping, but you can see the basic cost outlines.

This 32 cell pack is 12 amp hours, 2 sets of 6 AH cells. That’s a decent pack and if you do a run down test you will see that the watt hour figure is very solid. These cells hold their voltage. They are more fun to ride with because the voltage is quite steady, not dipping so much.

The real question is one of assembly. These are big cells, maybe huge cells next to an 18650. But that makes them easy to weld. Will people actually spot weld these cells? I don’t know. The welder is not an incidental. Right now, there is not much interest in welding. So, it would depend on having ebikes return to more of a DIY environment. All that would take is some economic pressure shifting the market down to poor people, which it isn’t right now.

To me, the best thing you could do for poor people is give them basic houses and basic transport. Then they can work and be OK economically. I remember when the county I live in decreed that you couldn’t live in a cheap mobile, a cheap RV, anything that wasn’t up to their standards of wealth. Now we know where that goes. Oakland will let you live in these options, and the prefab tiny house looks good in a lot of ways. If you look at movies from the 50’s or 60’s, there was a lot of basic housing. Now the rich can’t handle it, and they are sick of the homeless. But back to transport.

The best way to sell these LFP cells, the 32700 cells, would be to assemble them in modules. Micah Toll once had a crowdsource where he offered small modules of assembled cells, which could be soldered. He took a lot of heat and the idea died. If you simply took a machine spot welder and assembled these Nano cells into 16 series, you’d almost have an ebike battery, but a small one. If you put XT60 connectors on the modules, you could parallel them effortlessly. As far as balance leads or a BMS, I don’t know. A basic connector and an external BMS would be simple. Most batteries have protections from the charger and the controller. So, if you took two modules and paralleled them, you’d have a standard ebike battery.

Certainly this approach is open to criticism. It’s a CNC type welding process. It’s a safe cell that is rated for 2,000 cycles. I’d like to see the issues, but I don’t see anything that is a real business because it’s something anyone can do. I would note that the $2.70 per cell is US retail. I mean, if you go buy a few thousand in China, it could be quite a bit lower.

Battery Hookup is essentially doing this with a 32700, but he’s assembling 20 in parallel, a little brick with a lot of amp hours and low voltage. But he sells them in sets of 4 which makes a standard 12v battery, like for an RV cabin deep cycle.

Something is going to break the death grip of US ebike companies on the pack market. This is essentially a ‘hundred dollar’ pack that offers advantages at the price of bulk. For an ebike for people with limited incomes, it probably works. It’s not really a hipster pack.

opt nano.png32700 machine weld.png
 
Right now, there is not much interest in welding
I’m not understanding where you’re getting this idea. There are significant sales in welders and components. JP or Jakov started the small welder market and it lead to several good welders far superior to Sunnko(thieves). Several long multi year threads around. And likewise Several Facebook pages. Banggood now sells a battery powered version that is handy for small projects. But I’d never promote or suggest most eBikrs owners jump in. The water can be scalding. The cheap seat China makers CAN build a battery to customers specifications meeting all of Harry S posted standards. Not inexpensive, but decent quality and long service use.
 
If you want a single pack, maybe to just build an ebike, I'm not sure building is cost effective. There is a learning curve. Micah Toll has good videos and a good book. Tom at Battery Hookup has those 20p modules of the 32700 cells. I assume he gets them from a jobber, but he might own an automated welder. I've looked at the welders, the big ones that can weld packs. They are fast, and they don't add much to the cost of a pack if someone is using them steadily. If you machine weld the packs, you can probably get quality welds and then you can use the nicer nickel overlays. Someone who wants to do this as a business might want to invest in the welder, and they would definitely want a good source for the cells in China. The Chinese still seem to appreciate people who can provide steady contracts with big numbers.

I built 2 packs with a Bangood welder. It's a nice enough welder, portable, with a foot switch. There are some welding patterns that are clearer, as you assemble. You can take 4 cells, two up and two down. Weld across all the cells and call that the bottom. Do the parallel on top, two different strips. Now you only connect each set to the next in one place and you are always on top, not flipping. I put the Kapton tape on everything as I assemble, so there aren't live connections. I have shorted out a module of LFP. It burned off the top, but that was it. It's a good skill to have, but you want to be careful. Try to use welding patterns that are obvious, and use a volt meter to see if two connections might be live.

I'd like to see someone do the modules. I bounced it off Sriko, but no response.

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