Is there any way to buy real Panasonic 18650? + Discussion

[Kin]

For that matter, is there any chance Panasonic makes the same density batteries in a bigger size? Though, I guess obviously not, or else Tesla would be using it. I know Lyen has made a pack from them before, but I haven't been able to figure out where he bought them. There are possibly legit sellers on ebay, but at $10 a pop, which amounts .90$/wh, which isn't so cheap. Seems unfortunate they're so expensive, especially since they're not *that* exotic and have existed in certain Netbook batteries for 3+ years.

But where I want to turn to discussion, is to the topic of whether they're as cool as they initially seem to me. I have seen LFP say generally that the main reason why they are so high in density is simply because they have reduced everything that makes LiPo be able to deliver a load of power. Is that it? Optimizing the elements of power delivery to be best for the minimal space offered?

Is there anyone working towards the extreme Energydensity/kg of the panasonic cells, but with just slightly higher C rating? I can imagine that some high density cells at 2C maybe even 3C peak would be sweet options to deal with the peaks of ebiking. Or, maybe, parralelling some LiPo along with the high density cells.

Anyway, I'm going in circles, the main question is really
1) How expensive are the Panasonic 18650s? Is there any reliable place to buy them at a competitive price?
2) Is there any magic to them, or are they simply LiCo optimized for a very specific 1C rating with the best methods of getting 1C but nothing more?

 

[Philistine]

Pardon my ignorance, but is there a reason you want those over A123 prismatics? Apologies if that is a moronic question, its just that now that A123 pouches are more available than in the past, I am always curious why people who don't go lipo don't just go A123 pouches (unless they are on a really tight budget obviously). Are the Panasonic cells considerably cheaper?

 

[Kin]

Hi,

Definitively not an ignorant question. Panasonic 18650 would be a big step away from a123. Fewer cycles, more sensitive, less power delivery.

However, like LiPo, they still have much higher volumetric density as compared to a123 (LiPO4 in general), and decently higher capacity/kg density. So if you like the "neatness" of a low volume package, there are still a number of benefits to LiCo. Similarly, in any situation where you want above an hour of runtime, the high discharge rates of a123 aren't really needed so much, but weight and volume might be sensitive (like an EV).

That said, I'm really happy a123 has gone down in price. Another reason why I'm wondering why these panasonic cells are so expensive. They're mega-mass produced for laptops, so it seems more of a supply problem than a cost problem.

I do wish there was something like the Panasonics in density, maybe with slightly more power, larger size format, and prismatic shape.

 

[neptronix]

A123 pouches: 130wHr/KG, and you get rejected/backdoor cells. Availability has been mixed over the years. You also have to then figure out a way to interconnect the pouches. Nobody has found the best way to do this. but the cycle life is great, and safety is great.

RC Lipo: dangerous, but cheap, 150-160wHr/KG, high power, availability not a problem, no pouch soldering required and it hooks straight up to all sorts of balancing/charging hardware. Very convenient. Pretty small and light too.

Panasonic 18650: 200wHr/KG and higher. Low power, but if you want to build a pack for a very large range, it's the best cell you can currently buy. Pain in the ass to assemble a giant pack of 18650's though.

P.S. when you say 'lipo', you are referring to a pouch cell. Cylindrical cells are different. but yes, you are right in that there is a compromise between high power and high energy. The Panasonic cells are highly biased towards jamming as much energy in a cell as possible. You get 2C out of them in bursts by adding cooling and accepting terrible voltage drop, basically.

The type of cell you chose is different according to what you're going for. There is no perfect cell for every situation. But if you want the lightest and smallest pack, the Panasonics friggin' rock. I bet a 20AH / 36v pack is around 9lbs.

 

[neptronix]

Kin; the "high energy" Dow Kokams are better than RC Lipo in terms of energy density, and have a good cycle life like the A123's, but are a little more expensive than these Panasonics per watt-hour

I wonder if anyone bought those on the group buy. Didn't see many people hoppin' over them..

I am sure there is major markup on those Panasonic cells. How else could Tesla deliver a luxury car with 40kWh for $56k? Their price per watt hour is gonna be super low. Boy would a group buy on those be nice. I'd empty my savings for those. I want a >70 mile range pack that fits in the triangle of my bike.

 

[thepronghorn]

Looking at the data sheet below, the Panasonic 18650's that Tesla uses look to be extremely dense (~250 whr/kg) but fairly high internal resistance. Just look at the sag for only a 1C discharge. It might be worthwhile to take a power density hit to gain some better internal resistance.

http://industrial.panasonic.com/www-data/pdf2/ACA4000/ACA4000CE254.pdf

Notice that it also says the cells are not sold bare, they are only sold through authorized pack assemblers.

 

[Kin]

Yeah. So that 250wh/kg the beauty^. I think the newest Panasonic are even 3400mah at 1C in 18650 format (just another way to understand the density information you mentioned). That's craazzyyy.

But, the excitement lies in the question of whether it's new magic, or just optimization of existing technology. I assume that battery power deliverance depends largely on the cathode/anode point, and the movement between the cations/anions. Increasing the cathode/anode component presumably increases the potential reactions there, perhaps at the cost of taking up more space. Helping the charge carriers might happen in another way that's taking up space. But, if all that panasonic is doing is stripping away everything but the essentials, then a higher C panasonic pack would be pretty much the same as parralelling some cells that didn't have the components stripped away (i.e, LiPo). And, in the end, it wouldn't be anything /really/ new.

So I guess the "magic" I'm asking about is: Is this anything new? or are they just improving manufactoring technique?


Realizing that I have to finish some problem sets, and that there's way too much complexity in material science for me to read up on wikipedia and pretend to have any real understanding, I kind of question of the benefit of this kind of thread (it tends to be a bit full of circular what-ifs). But, I'm also really impressed by the random info other members bring in, so maybe someone can offer some insight.


Also, while officially they only sell to authorized retailers, the same applies to a123 but we seem to have sneaked through. Any way we can get our hands on these cells at a good price?

 

[velorelax]

Try http://www.evvatech.com. Reliable seller, but they only sell at least 10packs.
I use the CGR18650CH, 5C rating, better energy density than lipo and safer.
Good for medium power setups with a Bafang BPM or a 9C 2807.
Prices are around 5$ a piece

 

[neptronix]

Interesting site. In all my years, i have never heard of this company, nor have i found any other information on them from a google search.

Looks suspect, dude.

 

[velorelax]

evvatech isn't a reseller like bmsbattery who sells to individual customers, they normally sell bigger quantities.
But so far, they are nice to work with.

 

[Kin]

evvatech isn't a reseller like bmsbattery who sells to individual customers, they normally sell bigger quantities.
But so far, they are nice to work with.

Hey, in general, it seems many 18650 sellers are disgenuine, even comparing to LiPO4 sellers. My best guess is that I'm not sure what is their real business for individuals is, besides maybe selling to flashlight modders (who else uses 18650 cells?). At least with LiPO4, they have a small market of ebikers. When you say "they have been nice," how far are you into the situation? Purchased, not purchased? Received and tested, or not tested?

Agreeing with Neptronix, it's always a bit suspicious when these random sellers pop up and very hard to weed out from the bad.

 

[oatnet]

A123 pouches: 130wHr/KG, and you get rejected/backdoor cells.

:lol: You weren't around for it, but this hobby was BUILT on rejected/backdoor cells repurposed for ebikes. At any rate, nobody much cares about the provenance, as the cells we have been getting yield the rated AH, have the rated IR, and are on track for delivering the rated cycle life.

Availability has been mixed over the years.

??? These cells have been available for (2) years (1) month, and as usual I bought some of the first ones here. At the time when cell_man ran out (I bought him out on my 3rd order), new vendors were just starting to sell them, and now they are a commodity item available from a number of vendors.

You also have to then figure out a way to interconnect the pouches. Nobody has found the best way to do this. but the cycle life is great, and safety is great.

??? There have been many viable solutions for connecting the pouches, including these two methods I published:

----------->Spot-Welding a123 Prisimatic tabs<-------------

-------->Crimping a123 Tabs is good enough for 100a load<-----------

-JD

 

[Kin]

Hey Oatnet . I don't think Nepronix was really trying to trash the a123. If he was at all, it's probably because he loves his Icharger. As general statements I think it's true that the cells have come from shady areas at first [excluding Cellman. But the average person wouldn't bet on finding a very reliable and kind Brit who pops into China to start a small Ebike business], but that they're becoming better and more reliable as time goes on and the leak increases, so to speak.

Anyway, my main point is hopefully to quell a lithium fire if there's any chance of argument sprouting. I'm not denying that a123 is a pretty sweet technology. However, there still is a certain appeal to high density LiCo

 

[velorelax]

how far are you into the situation? Purchased, not purchased? Received and tested, or not tested?

11 packs ordered (1 sample and 10 for first production). 10S6P and 13S6P, all received within 2 weeks and tested OK. I am selling those in France, on my own bike, I run Lipo from Hobbyking, but the Panasonic are safer. Won't sell Lipo to customers. The Panasonic packs are half the weight of an A123Pack. They all came perfectly balanced and charged to 3,7V a cell for storage.

 

[Kin]

Pretty cool. I do hope you test the packs before selling to customers. Note for example, http://www.evvatech.com/sdp/1015379/4/pd-4967686/7674760-2083085/48V_E-Bike_Battery_Pack_18650_13S3P_10Ah.html . Claims 10Ah from a 3P pack, above feasible specs (unless they had the very best panasonics). If you look at the picture, even the label says 8.7Ah! Even that it quite high, 2.9ah cells.

Surely they must be resellers... I'm not sure how a single manufactorer could be selling a dozen different brand batteries. That said, a reseller is not necessarily bad. But prices are not that great, compared to the recent A123 offerings. 3ah cells for $6.3, probably before shipping? That's $.54/wh, for difficult to make packs. Some other batteries are pretty good (4C Sony cells 2.4ah for $2.8/cell). But, again, there's no guaranteeing these are good spec.

I mean, who am I to argue if you're happy, but they do seem somewhat suspicious and hard to weed through. What I do appreciate is that you've pointed me to the fact there do exist 18650 cells with higher C rating, but clearly they do come with substantial capacity loss.

 

[neptronix]

Thanks for chipping in oatnet. It's just that i don't see a lot of people on here using the A123s. I forgot that you had this stuff sorted - that is rarely mentioned. You have the best tab connection method i have seen so far, but frankly, it's a job i'd never want to do ( doing surgery on my lipos already gets my heart racing ).

I think there was a period of time when i was on here where there was no A123 20AH supplier. Cell_man hadn't mentioned he was selling them, and the supply was cut off at that point. I think only you were talking about being able to get them.

I know that used / backdoor cells was how this all started, but i guess that never interested me. I lurked the forums a long time before joining, but finally I got interested in doing my own build when i heard you could extract brand new A123 cells out of deWalt packs. Until then, i was just not interested.

So, different strokes for different folks. I want ultra high density for 100+ mile rides. But i also live in an upstairs apartment, so being able to carry the bike up and down is an issue. Even RC Lipo doesn't make that a reality, 2.5kWhr of it is 38lbs alone, on top of a bike that is around 35-40lb itself.


p.s. Kin - even if i had A123's i'd be using my iCharger to balance them...

 

[John in CR]

I've got a Panasonic battery factory less than 5 min away. I checked with them as soon as I knew anything about Li batts and a couple of times since, but unfortunately the largest Li cells they produce here are the little button size. It's been well over a year, so I guess it's time to check in with the head guy once again.

 

[Kin]

I've got a Panasonic battery factory less than 5 min away. I checked with them as soon as I knew anything about Li batts and a couple of times since, but unfortunately the largest Li cells they produce here are the little button size. It's been well over a year, so I guess it's time to check in with the head guy once again.

Sweet. Yeah, button cell might be a bit small. Look forward to hearing if there were any expansions.

 

[neptronix]

Let's do it. 20s2000p battery packs!

Most likely non-rechargeable though.

 

[oatnet]

I want ultra high density for 100+ mile rides.

You have me beat - 30 miles and I am exhausted.

-JD

 

[cwah]

I want 250wh/kg cells!!!!

 

[migueralliart]

A minute of searching gave me this

http://budgetlightforum.com/node/4008

nice discharge capabilities! I'm in for a group buy if anyone is interested in starting one.

 

[cwah]

Interested if I can get 250wh/kg batteries! But I haven't built a battery yet.

 

[neptronix]

A minute of searching gave me this

http://budgetlightforum.com/node/4008

nice discharge capabilities! I'm in for a group buy if anyone is interested in starting one.

I believe you are not reading this post correctly.
On 2C, one cell will sagging by 0.6v/cell!!!

That means that at 2C, a 20AH 10S ( 36v ) pack on a 40A load would have a 6 volt sag! that's pretty bad!
If the 1C rate means for 3V of sag on a 10S pack, that is still quite poor.

These cells will need to be ran at 0.5C or less for best performance and long cell life.

The official Panasonic discharge graph shows a rosier picture. So what is true.. ?

Great for a monster size pack.
But for a monster sized pack, the price adds up very quickly ( based on that eBay price )

$100 3.1AH
$200 6.2AH
$300 9.3AH
$400 11.4AH
$500 14.5AH
$600 19.6AH
$700 22.7AH
$800 25.8AH
$900 27.9AH
$1000 31AH <-- still only good for 31 amps maximum!!

That's around $1000/wHr !! remember that Tesla has said their battery cost is less than half of that? ...

 

[migueralliart]

A minute of searching gave me this

These cells will need to be ran at 0.5C or less for best performance and long cell life.

The official Panasonic discharge graph shows a rosier picture. So what is true.. ?

Great for a monster size pack.
But for a monster sized pack, the price adds up very quickly ( based on that eBay price )

$100 3.1AH
$200 6.2AH
$300 9.3AH
$400 11.4AH
$500 14.5AH
$600 19.6AH
$700 22.7AH
$800 25.8AH
$900 27.9AH
$1000 31AH <-- still only good for 31 amps maximum!!

That's around $1000/wHr !! remember that Tesla has said their battery cost is less than half of that? ...

For people with low current draw, it seems like a good solution.