What is it with 18650 batteries?

Den mandag den 27. april 2015 kl. 17.51.38 UTC+2 skrev Spehro Pefhany:

I'm guessing that it is the new regulations that lithium batteries must be checked then specially packed and market before they can be shipped

-Lasse

That would be my guess, too. And DigiKey has never been really good for batteries in my experience.

Spehro, I assume you've tried contacting Panasonic directly, or looking on their web page? Given that it's a common cell size, your best bet may be to waltz over to the local Batteries Plus (assuming they have stores in Canada) and see what they have.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

The holders would also accept standard-sized protected cells.

I believe these are the non-protected ones. In the US we have very screwed up tort law. Maybe they don't want the liability? Or maybe too much happened and some insurers said no? Seems you can still get them but I don't know this vendor:

--
Regards, Joerg 

http://www.analogconsultants.com/

I was told by a battery pack builder that they are contractually prevented from selling the individual cells and another said it was "illegal" (perhaps speaking informally).

Digikey does sell other lithium cells, which require special handling and marking (it slows the orders down because they have to come by ground).

I have not tried contacting Panasonic directly- they're a huge Japanese company and I doubt it would end well unless I wanted large quantities (and I don't).

Best regards,

--Spehro Pefhany

They appear to be saying that their factory is using the Panasonic cells to make protected cells, so the markings on the outside won't say "Panasonic". Trust us. hmmm..

There might be some relationship there with the protection- there seems to be two levels- short-circuit protection which uses polyfuses and short/over discharge protection which involves a whole bunch of parts. I have an almost unpopulated board that came out of an "Ultrafire" cell - just short circuit protected. That brand is generally thought to be one of the worst- and the cells weigh signficantly less than more credible ones. I pulled one apart- I'm guessing less than 25% of the rated capacity of "4500mAh". I have not done quantitative testing yet (will do when I get some holders in). I have an electronic load that does automated discharge curves so it should be easy to do some comparisons. Some people claimed they were recycled cells from bad packs, but this one just looks like a new badly made one.

Best regards,

--Spehro Pefhany

Here is a European disti and maybe these cells just don't have the company name on there?

But yes, one has to be careful to get the genuine stuff.

Sounds like with some of the bicycle light Li-Ion packs. At least there it's not a lot of money down the drain if one turns out to be a dud. So far I lucked out, only one dud out of three and for that I got the money back :-)

--
Regards, Joerg 

http://www.analogconsultants.com/

I found these, but assumed Spehro had already been to octoparts

George H.

I was thinking that they may be able to direct you to a distributor.

I worked on a product (which didn't make it to production, but that's another story) where we were planning on using Tenergy cells. Even though we were talking in quantities of 100/year they Tenergy apps engineers were still very attentive and informative.

Of course, I don't know if Tenergy has the cells you want.

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

Lodz Poland? Cheap like pierogi... but shipping by surface would be slow.

Best regards,

--Spehro Pefhany

People like Wal*Mart and McMaster have some semi-no-name cells (with protection). It feels a bit like the situation with security bits- you can pay $30 to a professional distributor and get a nice one, or get

100 crappy ones in a set for $5 from a dubious source (except that folks like Digikey etc. seem to have opted out).

Tenergy offers buttonless (have to be welded) Samsung cells (no price)

2600mAh. I assume they're legit.

"Ideal for building battery packs".

As well as their own branded batteries with protection and the same capacity (perhaps Samsung cells with added PCB- 3mm longer):

Thanks, that looks like a good lead!

Best regards,

--Spehro Pefhany

Hi, folks:-

There seems to be some kind of embargo (by agreement of mfr or by legislation?) on name-brand 18650 cells- for example, you can't buy the genuine Panasonic NCR18650B cells from Digikey or Mouser, even though they sell other Panasonic lithium cells.

Instead there are tons of fraudulently-labeled batteries from China with claimed capacities that are several times higher than reality.

This kind of cell is used in many laptop battery packs, 'tactical' flashlights, head lamps, and other consumer goods.

You can buy battery **holders** from Digikey but not batteries. It would be a very nice size/capacity if legitimate product was available.

The fake batteries (air shipped as 'gift')? are surely more dangerous than allowing sales of name-brand products which would be shipped via ground if from a legitimate distributor.

What's the story here? Unintended consequences??

Best regards,

--Spehro Pefhany

Those are the same batteries as I have in my new Tesla, great stuff. A bat is $30K USD.

Cheers, Harry

I wonder how many of the 7,000 or whatever it is cells ($4/cell?) could be removed without you noticing..

Best regards,

--Spehro Pefhany

Good pierogi takes time. (I didn't check the details.. obliviously.)

George H.

Amazon claims to have the real thing.

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Check

. I've bought different kinds of cells and packs from them for products that ship 50-200 units per year.

-- mikko

Harry might not notice, but the computer in his Tesla probably would. :) I'm not sure about Teslas, but I know Priuses have a "sense" wire to the battery computer from every other cell pack in the battery; essentially there's a tap every 14.4 V (out of 273.6 V total). As far as I know, these wires are not used to take traction current or deliver charge current; they are just there so the battery ECU can monitor the condition of the whole stack. If you have the Toyota scan tool, you can get the voltage readings at each tap.

Matt Roberds

it is also common for multi cells RC pack to have a connector with taps for each cell, it is used to balance the cells when charging, i.e. there is basically a voltage clamp across each cell at the max voltage so it doesn't get overcharged

-Lasse

Dollarama , Tech-1 06-3040589, 'POWERbank' CDN$3 , includes case, connectors and output boost converter for 5V USB supply.

1.5Ahr ~5Whr under moderate loads.

RL

Spehro Pefhany schreef op 04/27/2015 om 05:55 PM:

It's because things can seriously go wrong in the hands of people who do not know how to deal with these kind of cells. For starters you'll need extra circuitry to prevent overcharge, deep discharge, discharge and charge current limit. You can buy these kind of cells if you have the right certifications and basically are a manufacturor of battery packs.