[KX1] A LiFePO4 internal battery option

[Chip Stratton]

I found some LiFePO3 batteries that fit well within the KX1 case, and
thought I would share:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14075

These are a different Lithium chemistry (same as A123 cells) than the more
common LiPoly cells. Their fully charged voltage is 3.6 V and they are
essentially fully discharged at 3.0 V. They are more tolerant of overcharge
and over-discharge than normal LiPoly cells too. I put two packs in series
in place of the AA cell holders in the KX1, to give a 14.4 V pack fully
charged, while taking up less space and weighing less. They are also almost
incredibly inexpensive. Downside is you only have 700 mAh to work with, and
with the higher voltage the KX1 will drink more heavily from your battery.
Still, this solution should give at least 3 hours or more of normal use -
plenty for me for an afternoon out.

The downside is that you need an appropriate LiFePO4 battery charger with
the appropriate "balance" charge connectors. I use a Cellpro 4S with a JST
type adapter board (to match the connectors).

Chip
AE5KA
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[k6dgw]

On 3/27/2011 7:02 PM, Chip Stratton wrote:
> I found some LiFePO3 batteries that fit well within the KX1 case, and
> thought I would share:

I wouldn't put any high energy density battery inside any of my radios.
  The probability of a problem is very small.  The impact if the
probability becomes 1.0 is a new radio at the least, and possibly more.
  My LiPoly for my KX1 [about the size of a small box of matches] is on
a pigtail I can grab and fling off if it catches fire.  One has.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2011 Cal QSO Party 1-2 Oct 2011
- www.cqp.org
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[Chip Stratton]

Fred's concern's noted. Consider however how infrequently laptops and cell
phones catch fire and explode compared to the numbers in use - and almost
all now use LiPoly or the less common (but safer) LiFePO4 technology. With
any rechargeable Lithium technology proper charging techniques and
discharging habits are important for longevity and utmost safety.

I posted a link to the wrong battery pack. They appear to be the same, but
the ones linked to are not in stock. These are the ones I am using:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16807

I can't personally vouch for the quality of these particular batteries, only
time will tell.

Chip
AE5KA
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[Rick Commo-2]

Well, LiFePO4 is a much safer technology than lithium ion or lithium poly.
There are quite a few YouTube videos on LiFePO4.  One interesting one in
which a big flat pack LiFePO4 battery is hacked with a sheet metal cutter
while it continues to operate.  This is from Tenergy a manufacturer of a
batteries using a number of technologies.

YouTube
http://www.youtube.com/watch?v=zwIl8f3WI0s

Tenergy's LiFePO4 page
http://www.tenergybattery.com/index.php?page=shop.browse&category_id=21&opti
on=com_virtuemart&Itemid=27

Some time ago I saw a video (which I can't locate now) where a LiFePO4 had a
drill put through it.  There was some minor smoking and that was about it.

Is this my recommendation to put it a KX1?  Well, anything I say would be
pretty empty as I am not a KX1 owner, but I probably would give it some very
serious thought.

-rick, K7LOG



-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Chip Stratton
Sent: Sunday, March 27, 2011 8:04 PM
To: Elecraft Reflector
Subject: Re: [Elecraft] [KX1] A LiFePO4 internal battery option

Fred's concern's noted. Consider however how infrequently laptops and cell
phones catch fire and explode compared to the numbers in use - and almost
all now use LiPoly or the less common (but safer) LiFePO4 technology. With
any rechargeable Lithium technology proper charging techniques and
discharging habits are important for longevity and utmost safety.

I posted a link to the wrong battery pack. They appear to be the same, but
the ones linked to are not in stock. These are the ones I am using:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16807

I can't personally vouch for the quality of these particular batteries, only
time will tell.

Chip
AE5KA
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[Leigh L. Klotz Jr WA5ZNU]

Those are 6.6v, so I guess you use a pair?

I've been using LiFePO4 in a lot of things, but haven't seen these that fit in the KX1.  At 700mAH they're a bit small, but the constant operating voltage is nice.

You might take a look at these, which are available at Fry's and Amazon:
http://www.powergenix.com/?q=products/nizn-quick-charger

At 1.8v charged you get almost 11v out of 6 of them in the existing AA slots.  Of course, you have to remove them to charge. The self discharge isn't as good as LiFePO4 but it's not bad either.

Leigh/WA5ZNU

[Chip Stratton]

I've been using the Powergenix NiZn cells too, and they do give a usefully
higher pack voltage than even the Energizer Lithium AA cells. They are not
as easy to manage as Nimh  cells, however. You have to use the supplied
charger with them, which seems not to initiate recharging unless the cell is
significantly drained. This makes it hard to keep them topped up. It also
seems to be hard to discover the state of a given cell since the open
circuit voltage does not fall much when nearing depletion. Their total
capacity under load appears to be quite a bit less than their ratings.
Basically there isn't enough information about their characteristics or
charging requirements to manage them optimally. Maybe that will change with
time, but they don't seem to be catching on, since I've found them at
"Tuesday Morning" stores, which seems to be where many failing products go
to die.

Chip
AE5KA

On Mon, Mar 28, 2011 at 12:30 AM, Leigh L. Klotz Jr WA5ZNU <[hidden email]
> wrote:

> Those are 6.6v, so I guess you use a pair?
>
> I've been using LiFePO4 in a lot of things, but haven't seen these that fit
> in the KX1.  At 700mAH they're a bit small, but the constant operating
> voltage is nice.
>
> You might take a look at these, which are available at Fry's and Amazon:
> http://www.powergenix.com/?q=products/nizn-quick-charger
>
> At 1.8v charged you get almost 11v out of 6 of them in the existing AA
> slots.  Of course, you have to remove them to charge. The self discharge
> isn't as good as LiFePO4 but it's not bad either.
>
> Leigh/WA5ZNU
>
>
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/KX1-A-LiFePO4-internal-battery-option-tp6213539p6213762.html
> Sent from the Elecraft mailing list archive at Nabble.com.
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[Ignacy]

 have lower energy density than regular Li-Ion rechargeables but due to lower voltage one can use 4 of them for about 14 V max as opposed to 3 of the regular ones with 12V max. For K1 the 3 Li-Ion would be a better fit as 10-12V is sufficient and weight is half of  LiFePO3. The last one are better IMHO when the minimum voltage is >11V, e.g., for regular HF radios including K3.

I have the regular Li batteries in K2 for many years and never a problem except higher Ah at 1/4 weight of lead acid.. The only trouble is a need for connecting to an external charger. A simple choice is a small board that attaches to a laptop charger and contains adjustable 1A regulator.

Ignacy, NO9E