Time to build a lithium battery from 18650 or 26xxx

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Time to build a lithium battery from 18650 or 26xxx

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Prices are around a dollar a cell. What is a good voltage 3.7 or 3.2. What's the danger? What are the benefits?. Soldering tabs vs welding. I have seen the larger cells for two dollars.  I have several projects that need. Batteries. Any videos or books that might be a good learning experience? A hundred cells at 64 volts would yield an 11 ah pack. BMS and charger would be more expensive. Lawrence Rhodes
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Re: Time to build a lithium battery from 18650 or 26xxx

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I was into this and found out this very complicated , there are 27ah
cells
https://www.techdirectclub.com/800-watt-hour-solar-ev-scooter-backup-battery-pack-8-cells-lithium-ion/ 
and theres other  on there.



On 2019-05-12 23:04, Lawrence Rhodes via EV wrote:

> Prices are around a dollar a cell. What is a good voltage 3.7 or 3.2.
> What's the danger? What are the benefits?. Soldering tabs vs welding.
> I have seen the larger cells for two dollars.  I have several projects
> that need. Batteries. Any videos or books that might be a good
> learning experience? A hundred cells at 64 volts would yield an 11 ah
> pack. BMS and charger would be more expensive. Lawrence Rhodes
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Re: Time to build a lithium battery from 18650 or 26xxx

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Where are you finding cells for $1 each? Going rate for 18650s (new) is
$180/kWH or so, which for a typical 2.6AH cell would be $1.73.

Li-Ion (and related sub-chemistries, e.g. NMC, LMO (uncommon), LCO, etc.)
are 3.7V, and are higher energy density but less "safe".

LiFePO4 is 3.2V, and is considered more safe, but is less common, more
expensive, and lower energy density. That said they usually have high/er
power density.

I solder, but that's because I don't have space/money for a spot welder (at
least not a quality one). Cheap spot welders aren't too good, and results
are mixed. Too much power and you blow a hole in the cell, too little and
you get weak connections. Cleaning up is also annoying if you need to change
out a cell. I prefer to solder, with individual cell fuses for each cell (I
use 30ga tinned copper wire, which blows at ~20A in a short circuit). Better
is using individual glass fuses with solderable legs, which go down to 0.5A
in rating, but the breaking point experimentally appears to be about twice
the rating.

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Re: Time to build a lithium battery from 18650 or 26xxx

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On 2019-05-13 16:22, jkenny23 via EV wrote:

theres lots of YT vids about spot welding with simples nachines

> Where are you finding cells for $1 each? Going rate for 18650s (new) is
> $180/kWH or so, which for a typical 2.6AH cell would be $1.73.
>
> Li-Ion (and related sub-chemistries, e.g. NMC, LMO (uncommon), LCO,
> etc.)
> are 3.7V, and are higher energy density but less "safe".
>
> LiFePO4 is 3.2V, and is considered more safe, but is less common, more
> expensive, and lower energy density. That said they usually have
> high/er
> power density.
>
> I solder, but that's because I don't have space/money for a spot welder
> (at
> least not a quality one). Cheap spot welders aren't too good, and
> results
> are mixed. Too much power and you blow a hole in the cell, too little
> and
> you get weak connections. Cleaning up is also annoying if you need to
> change
> out a cell. I prefer to solder, with individual cell fuses for each
> cell (I
> use 30ga tinned copper wire, which blows at ~20A in a short circuit).
> Better
> is using individual glass fuses with solderable legs, which go down to
> 0.5A
> in rating, but the breaking point experimentally appears to be about
> twice
> the rating.
>
> --
> Sent from:
> http://electric-vehicle-discussion-list.413529.n4.nabble.com/
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Re: Time to build a lithium battery from 18650 or 26xxx

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Go on eBay.  100 cells. $100. Here is a search. New and pre owned cells. Not sure I would trust pre owned.  https://www.ebay.com/sch/i.html?_nkw=100+lithium+cells
  Lawrence Rhodes
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Re: Time to build a lithium battery from 18650 or 26xxx

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On 15 May 2019 at 8:12, Lawrence Rhodes via EV wrote:

> New and pre owned cells. Not sure I would trust pre owned.

You may not be sure, but I'm positive I wouldn't.  You don't know where
those cells have been.

These days, both Ebay and Amazon are so overrun with garbage and counterfeit
products that they're getting close to useless.  You can't even trust name
brands any more if you're buying from one of those operations.

A lot (maybe most) of the amazingly cheap lithium batteries you see on Ebay
are made from salvaged laptop battery cells.  As you might guess, they're
close to junk when they're sold, and and generally beyond junk in a few
months.  

As I always say, you don't always get what you pay for, but you very seldom
get what you don't pay for.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Re: Time to build a lithium battery from 18650 or 26xxx

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Check out Jehu Garcia on YT. He often organises bulk buys of cells.

On Wed, 15 May 2019 at 15:38, EVDL Administrator via EV
<[hidden email]> wrote:

>
> On 15 May 2019 at 8:12, Lawrence Rhodes via EV wrote:
>
> > New and pre owned cells. Not sure I would trust pre owned.
>
> You may not be sure, but I'm positive I wouldn't.  You don't know where
> those cells have been.
>
> These days, both Ebay and Amazon are so overrun with garbage and counterfeit
> products that they're getting close to useless.  You can't even trust name
> brands any more if you're buying from one of those operations.
>
> A lot (maybe most) of the amazingly cheap lithium batteries you see on Ebay
> are made from salvaged laptop battery cells.  As you might guess, they're
> close to junk when they're sold, and and generally beyond junk in a few
> months.
>
> As I always say, you don't always get what you pay for, but you very seldom
> get what you don't pay for.
>
> David Roden - Akron, Ohio, USA
> EVDL Administrator
>
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
> EVDL Information: http://www.evdl.org/help/
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> reach me.  To send a private message, please obtain my
> email address from the webpage http://www.evdl.org/help/ .
> = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
>
>
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Re: Time to build a lithium battery from 18650 or 26xxx

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Those $100 listings as others have mentioned are used cells. You'll find that
based on their tested capacity they're not a very good deal also.

As I mentioned, the market rate is about $180/kWH for new cells, sometimes
you can find a better deal on new old stock or bulk buys. I try and maintain
a list of deals on batteries here: http://bit.ly/18650DLZ 

There's also an active Discord group for DIY powerwall builders, and we
often post deals as they come around, here's the link:
https://discord.gg/gfB5KsJ

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Re: Time to build a lithium battery from 18650 or 26xxx

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David is correct.  Lots of junk.  However if you question or possibly call the vendor you can get a better sense of their honesty.  The $2,400 worth of Valence batteries I got for $200 was a useful bargain.  I was afraid that the sag I got from the San Francisco hills would croak them carrying my 240 pounds. So far so good.  Lawrence Rhodes.
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