[K2] LiFePO4 replacement for internal SLA battery in K2

[inventor61 .]

I had strongly considered the LiPo type secondary-cell power packaging
option and rejected it.

Energy density in that chemistry/package is amazing of course.  But that
equation is also true of a bomb.  I have no problem with the LiPo in my
iPad, Galaxy S5 phone, and laptop, so, it's not a blind bias.

It doesn't take too much YouTube searching to find dramatic examples of
LiPo powered RC vehicles and the like bursting into flames.

There's a good reason that *all* these lithium cells are considered hazmat
now, not just the lithium thionyl chloride ones ... on failure, those burn
and emit nerve gas; they are Class 9 hazmat!  They are also not
rechargeable anyway.

Because this particular power pack would be fully enclosed in the
metal-cased K2, and would be in the 9 ampere-hour range in this desired
form factor ... if such a LiPo pack decided to self-immolate, the rig would
not only be destroyed but I'd have a real secondary incendiary hazard on my
hands.

The charging, power regulation and protective circuitry, etc., needed to
use the LiPo chemistry/packaging inside a K2 took that consideration off
the table for me.  YMMV.

The 'safe-failure-mode' secondary-cell chemistries I considered were NiMH
and LiFePO4.

The NiMH almost won.

By the way, I have the special spot-welder device and strap/bracket
supplies needed to fabricate my own packs.  Extensive experimenting with
NiMH cells really had me convinced to go that way for some time.

Then, I got some newer LiFePO4 cells and also some new LiCoO2 cells, and
started the "2015 edition" revisiting of the selection analysis.  I had
last looked at the issue in 2010.

It didn't take long before my own clumsiness lit one of the 18650-size
LiCoO2 cells up.  I caught the mistake just as it was about to get really
serious.  Lesson learned.  Now I know why the manufacturers of those
include the built-in-per-cell safety circuit option!  The cells I tried
were the 'raw' and unprotected type, selected purposefully so as to not
have the size, cost, and loss of the protective circuitry.  For these and
other reasons, this chemistry/packaging option was rejected for the
particular use-case.

I could not achieve a better-than-the-SLA result with NiMH.

Hope my describing a portion of the ferreting process in a bit more depth
is of use to others.

The K2 is a remarkably competent field radio.  Being able to actually use
it in the field, conveniently, makes my now-teenage rig all the more
valuable to me.  Having a modern internal power source will just be icing
on an already tasty cake.

73  Steve KZ1X
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[Jim Brown-10]

On Sat,9/12/2015 8:37 AM, inventor61 . wrote:
> I had strongly considered the LiPo type secondary-cell power packaging option and rejected it.

There are mfrs of well protected LiFePO4 battery packs. Two I found are
Battery Space and Bioenno Power. Both make packs in a wide variety of
shapes to fit in the space available in existing products. They include
the circuitry inside the pack required to equalize charge and avoid
unsafe conditions. These batteries are not cheap, but you'll appreciate
the increased energy density.

If you're concerned about fitting the battery inside the radio, buy a
battery and use it outboard. I bought a 20Ah battery from Bioenno Power.
It came with two connectors, one a concentric connector for charging,
the other a Power Pole. I'm past the backpacking stage, but I bought the
battery to support a 6M grid trip to CM79 by a younger ham. He really
appreciated the reduced weight.

Both of these companies sell 12V LiFePO4 batteries range from 3Ah to 125Ah.

73, Jim K9YC
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[Myron WVØH]

BatterySpace does not add balance circuitry, only over/under I/V protection. What that means is when you charge, the first cell to reach its full voltage, the charge terminates leaving the other cells undercharged. Nothing offered on their website contains any balancing function.

You can get balancing circuitry added but you have to contact them and then they will add what they call "equilibrium" circuitry, to perform the balance function that you and I know.

Myron WVØH
Printed on Recycled Data

> On Sep 12, 2015, at 10:46 AM, Jim Brown <[hidden email]> wrote:
>
>> On Sat,9/12/2015 8:37 AM, inventor61 . wrote:
>> I had strongly considered the LiPo type secondary-cell power packaging option and rejected it.
>
> There are mfrs of well protected LiFePO4 battery packs. Two I found are Battery Space and Bioenno Power. Both make packs in a wide variety of shapes to fit in the space available in existing products. They include the circuitry inside the pack required to equalize charge and avoid unsafe conditions. These batteries are not cheap, but you'll appreciate the increased energy density.
>
> If you're concerned about fitting the battery inside the radio, buy a battery and use it outboard. I bought a 20Ah battery from Bioenno Power. It came with two connectors, one a concentric connector for charging, the other a Power Pole. I'm past the backpacking stage, but I bought the battery to support a 6M grid trip to CM79 by a younger ham. He really appreciated the reduced weight.
>
> Both of these companies sell 12V LiFePO4 batteries range from 3Ah to 125Ah.
>
> 73, Jim K9YC
> ______________________________________________________________
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[Jim Brown-10]

Thanks for that info, Myron. VERY important!

73, Jim K9YC

On Sat,9/12/2015 11:33 AM, Myron WVØH wrote:
> BatterySpace does not add balance circuitry, only over/under I/V protection.

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[Bill W4ZV]

inventor61 . wrote

I had strongly considered the LiPo type secondary-cell power packaging
option and rejected it.

Energy density in that chemistry/package is amazing of course.  But that
equation is also true of a bomb.  I have no problem with the LiPo in my
iPad, Galaxy S5 phone, and laptop, so, it's not a blind bias.

It doesn't take too much YouTube searching to find dramatic examples of
LiPo powered RC vehicles and the like bursting into flames.

There's a good reason that *all* these lithium cells are considered hazmat
now, not just the lithium thionyl chloride ones ... on failure, those burn
and emit nerve gas; they are Class 9 hazmat!  They are also not
rechargeable anyway.

Because this particular power pack would be fully enclosed in the
metal-cased K2, and would be in the 9 ampere-hour range in this desired
form factor ... if such a LiPo pack decided to self-immolate, the rig would
not only be destroyed but I'd have a real secondary incendiary hazard on my
hands.

The charging, power regulation and protective circuitry, etc., needed to
use the LiPo chemistry/packaging inside a K2 took that consideration off
the table for me.  YMMV.

I understand and agree for your use case of mounting the battery internally in the K2.  My "fail safe" is to never use an internal battery and thus avoid issues of fire, leakage, etc.  I always charge and mount my LiPOs externally.  It's certainly possible to abuse LiPOs and cause them to catch on fire, but as you stated, there are plenty of devices that successfully use them internally...significantly more than LiFePO4s when you consider the volumes of cell phones, tablets, PCs, models, drones, etc. that use LiPOs.

Just an FYI for anyone interested, the "11.1V 4500mAh 3S 30C Lipo" listed on a popular auction site for $24.36 is actually available for $20 if you use "Make Offer" (I just bought one).  Of course you also need a balancing charger (available for around $20) to properly charge and store LiPOs.  You cannot beat the energy density (mAH per ounce) of a LiPO but they DO REQUIRE proper care.

73,  Bill  W4ZV

[k6dgw]

On 9/13/2015 3:23 AM, Bill W4ZV wrote:

> I understand and agree for your use case of mounting the battery internally
> in the K2.  My "fail safe" is to never use an internal battery and thus
> avoid issues of fire, leakage, etc.  I always charge and mount my LiPOs
> externally.  It's certainly possible to abuse LiPOs and cause them to catch
> on fire, but as you stated, there are plenty of devices that successfully
> use them internally...significantly more than LiFePO4s when you consider the
> volumes of cell phones, tablets, PCs, models, drones, etc. that use LiPOs.
>
FWIW: I had a small 900 mAh LiPoly about the size of a small match box
catch fire while using it to power my KX1.  I got it at the local RC
store.  It was external on a short pigtail, I was on the deck with my
AlexLoop, and I was able to yank it from the KX1 and fling it over the
rail down onto the gravel driveway.  The pyrotechnic display continued
for about 4 min.  Really glad I wasn't in the house.

> Just an FYI for anyone interested, the "11.1V 4500mAh 3S 30C Lipo" listed on
> a popular auction site for $24.36 is actually available for $20 if you use
> "Make Offer" (I just bought one).  Of course you also need a balancing
> charger (available for around $20) to properly charge and store LiPOs.  You
> cannot beat the energy density (mAH per ounce) of a LiPO but they DO REQUIRE
> proper care.

I've had poor results from the couple of batteries I bought off a well
known auction site.  One was billed as a 9 Ah LiFePO4 and the other as a
4.5 Ah LiPoly.  Both exhibited a linear, downward discharge curve and my
K2 quit fairly quickly on low voltage.  When I recharged it, the "9 Ah"
one took 1,300 mAh which, to a first approximation, is about the usable
capacity I got from it.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org


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