[time-nuts] Li-ion Battreries

Sun Jan 22 23:53:02 UTC 2017

In the days prior to my recent retirement, when I was directing research at
a large VA Medical Center, one of our projects used inordinate quantities
of 18650 Li-ion batteries. We found in short order that buying from Amazon
or eBay was penny wise and pound foolish. Rather than flogging the internet
for deals, trying to save a few bucks, just buy Panasonic, Duracell, Sanyo,
Samsung Sony or LG directly from an authorized dealer.

As Chris pointed out, ammo boxes work are excellent for storage. We found
the manufacturer''s packaging perfectly adequate. They aren't bombs, guys.
Use sensible precautions and get on with it.

On Sunday, January 22, 2017, Chris Albertson <albertson.chris at gmail.com
<javascript:_e(%7B%7D,'cvml','albertson.chris at gmail.com');>> wrote:

> I'm using Lithium batteries too.   Button for everything.   For stationary
> lab bench use where AC mains is available and all I want is back up our the
> lead/acid gel cells work fine.  They are cheap, large and heavy and will
> take abuse and don't normally catch fire.
>
> For the mobile devices that I like to build nothing beats Lithium
> batteries.   I've been using the kind sold for use on remote controlled
> drone aircraft.   They have incredible power density and low cost.  Their
> biggest down side (an advantage to me) is their lack of consumer
> appropriate packaging.  The cells are only shrink wrapped and are easy to
> damage.  I change them with a programable "balanced" charger that is
> commonly used by hobbyists.
>
> I have found that YES you can start a fire from carelessly handing Lithium
> batteries.  You do have to understand how to use them and keep them
> packaged such that they remain safe even if they fail or (more likely) you
> make some mistake.   I keep them in fire proof glass fiber/silicone
> envelopes then inside a tightly close steel "ammo box".     When in use
> they are installed in the mobil device I built in a metal compartment (I
> use those old fashion Japanese lunch boxes, they are like Tupperware but
> made completely of metal)
>
> Get these batteries at any of the Hobby supply outlets (NOT eBay, lots of
> fakes there.)
> Here is just one example of the last set I bought
> https://hobbyking.com/en_us/zippy-flightmax-4000mah-4s1p-20c.html
>
>
>
> On Sun, Jan 22, 2017 at 9:13 AM, Adrian Godwin <artgodwin at gmail.com>
> wrote:
>
> > Recovered cells aren't only sold through ebay parts adverts - they're
> also
> > used for production. I recently bought a few cell phone boosters which
> > consist of an 18650, a charge circuit and a voltage booster to 5V.
> >
> > They were low cost and nicely made with an extruded aluminium case and
> they
> > worked very well in my application. But on taking one apart, it was
> > apparent that they'd used a recovered cell.
> >
> > I've no complaints given the price, but be aware that the cell phone
> packs
> > may not be new either.
> >
> >
> > On Sun, Jan 22, 2017 at 4:48 PM, Didier Juges <shalimr9 at gmail.com>
> wrote:
> >
> > > Well worth mentioning that you have found a reputable vendor. I may
> give
> > > them a try.
> > >
> > > A while back, I bought a dozen 18650 inexpensive(<$5 each) cells from 3
> > > vendors picked at semi-random on eBay (4 from each) for evaluation and
> I
> > > tested each one of them with a data logger.
> > > The best one had about half the advertised capacity, the others went
> down
> > > from there. Important to observe that none of the set I bought were
> even
> > > remotely matched, a crucial consideration if you are going to put them
> in
> > > series (a balancer will only ensure your pack is no better than the
> worst
> > > cell in the pack).
> > > Many of the 18650 cells you find on eBay (and maybe other places) are
> > > actually coming from old laptop battery packs that normally should have
> > > been discarded/recycled.
> > >
> > > In my anticipated application, I only needed one cell (to be followed
> by
> > a
> > > small boost converter), so the issue of balance and matched set was not
> > > important, but simply I needed the capacity and none were remotely
> > > satisfactory. I ended up using cell phone booster packs, since I needed
> > 5V
> > > anyway.
> > >
> > >
> > > On Sun, Jan 22, 2017 at 9:44 AM, Bert Kehren via time-nuts <
> > > time-nuts at febo.com> wrote:
> > >
> > > > I use 4 cell balancing and protection circuits, cost a couple of $
> more
> > > but
> > > >  well worth it, I use holders because of  limited availability of
> cells
> > > > with  straps, but rest assured they are held down (discarded PCB)'s,
> > > > I on purpose did not get into technical details I was only trying to
> > > share
> > > > reliable sources, based on disappointing past experiences.
> > > > Bert Kehren
> > > >
> > > >
> > > > In a message dated 1/22/2017 10:00:45 A.M. Eastern Standard Time,
> > > > attila at kinali.ch writes:
> > > >
> > > > Hoi  Bert,
> > > >
> > > > On Sat, 21 Jan 2017 08:08:22 -0500
> > > > Bert Kehren via time-nuts  <time-nuts at febo.com> wrote:
> > > >
> > > > > purchased  _2x   Samsung 35E 3500mAh 10A 18650 High Drain
> > Rechargeable
> > > > Battery
> > > > >  INR18650-35E_
> > > > >
> > > > (http://www.ebay.com/itm/112173495496?_trksid=p2060353.
> > > > m2749.l2649&ssPageName=STRK:MEBIDX:IT)   for two reason 10 A load
> and
> > > > good price. These
> > > > > cells have no  protection, which I want, since I will for  our
> > > > applications
> > > > > stack 4 with a 4  cell controller and in two application also
> > parallel
> > > > cells
> > > > > for a total of  8.  I have now completed my  tests  and concentrate
> > my
> > > > > battery work on using these   cells.
> > > > > After having tested 26650 cells with disappointing   results my
> focus
> > > is
> > > > on
> > > > > 18650. I am sure there will be 26650 cells  available, but  right
> now
> > > our
> > > > > focus is on 18650.
> > > > > I have  no connection in any way with these two sources,  but think
> > it
> > > > may
> > > > > be helpful for those that look for batteris and do not want to   go
> > > > through
> > > > > the process I went through.
> > > >
> > > >
> > > > Some  small remarks: 18650 is by far the most common form factor
> > > > of Li-Ion  batteries on the market. This is IMHO the better choice
> > > > than the 26650 if  you want to be able to replace them in 10-20
> years.
> > > >
> > > > If you stack Li-*  batteries, you will need to have a controller that
> > > > monitors each cell  individually while charging or has some other
> means
> > > > of ensuring that none  of the cells are overcharged (or rather that
> > they
> > > > are charged the same  amount). This kind of circuit is called
> balancer.
> > > > A protection circuit does  _not_ replace a balancer. The protection
> > > circuit
> > > > is only to protect against  catastrophic failure. Ie it is still
> > possible
> > > > to overcharge a battery even  if it has a protection circuit. You
> also
> > do
> > > > not know what the protection  circuit does to protect the cell. There
> > are
> > > > a lot of chips out there, that  simply open a switch and thus
> > disconnect
> > > > the cell. In this case, the  protection circuit of one cell will
> > > disconnect
> > > > the whole stack and break  charging.
> > > >
> > > > A lot of the multi-cell Li-Ion charger chips have integrated  cell
> > > > protection
> > > > circuitry. Ie if you use one of them, you will not need an
> additional
> > > > protection circuit. But be aware, the regulation for battery
> > protection
> > > > circuit states that the circuit has to be wired fix onto the  battery
> > > > in a way that this connection cannot be broken (without breaking  the
> > > > housing of the battery pack). The reason for this is, i think,
> pretty
> > > > obvious. I would recommend that you solder each cell  indidividually
> > > > into your circuit instead of using some kind of holder. Or  if you
> are
> > > > using a holder, make it such that there is no chance any of the
> cells
> > > > can be accidentally short circuited.
> > > >
> > > > Attila Kinali
> > > > --
> > > > Malek's Law:
> > > > Any simple idea will be worded in the most complicated  way.
> > > > _______________________________________________
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>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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