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Alternative battery for K2?

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Alternative battery for K2?

TF3KX
Hi everyone.

Has anyone any experience or suggestions on replacing an aging internal K2 battery (the standard lead-acid type) with one of the newer, lighter and more energy-dense batteries? I know there were some safety concerns with lithium-based batteries early on, but now that they are are used in all sorts of electronic gadgets, wouldn't there be some that would have the right form factor and voltage to fit in for the existing K2 battery?
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Re: Alternative battery for K2?

Don Wilhelm-4
The charging scheme for the K2 internal battery is based on using an SLA
battery.  If the battery is changed to another battery chemistry, the
charging circuit would have to be modified to match the charging
requirements of the replacement battery type.
Since Lithium batteries require very special charging techniques, this
is a matter that is not to be taken lightly.
A simple replacement of the K2 SLA battery with another battery
chemistry would have to be a redesign of the charging mechanism.

73,
Don W3FPR

On 8/15/2015 11:33 PM, TF3KX wrote:

> Hi everyone.
>
> Has anyone any experience or suggestions on replacing an aging internal K2
> battery (the standard lead-acid type) with one of the newer, lighter and
> more energy-dense batteries? I know there were some safety concerns with
> lithium-based batteries early on, but now that they are are used in all
> sorts of electronic gadgets, wouldn't there be some that would have the
> right form factor and voltage to fit in for the existing K2 battery?
>
>
>
> --
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Re: Alternative battery for K2?

vk2rq
In reply to this post by TF3KX
I use a 4-cell LiFePO4 battery, with Anderson Power Pole pigtail, connected externally to the K2. Easy to change batteries without having to open the rig, and by recharging the battery external to the radio there is no risk of engulfing my beloved K2 in a spectacular ball of flame.

-- 
73 de Matt VK2RQ

Le 16 août 2015 à 1:33:44 PM, TF3KX ([hidden email]) a écrit:

Hi everyone.  

Has anyone any experience or suggestions on replacing an aging internal K2  
battery (the standard lead-acid type) with one of the newer, lighter and  
more energy-dense batteries? I know there were some safety concerns with  
lithium-based batteries early on, but now that they are are used in all  
sorts of electronic gadgets, wouldn't there be some that would have the  
right form factor and voltage to fit in for the existing K2 battery?  



--  
View this message in context: http://elecraft.365791.n2.nabble.com/Alternative-battery-for-K2-tp7606331.html 
Sent from the Elecraft mailing list archive at Nabble.com.  
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Re: Alternative battery for K2?

Greg Troxel-2
In reply to this post by Don Wilhelm-4
Don Wilhelm <[hidden email]> writes:

> The charging scheme for the K2 internal battery is based on using an
> SLA battery.  If the battery is changed to another battery chemistry,
> the charging circuit would have to be modified to match the charging
> requirements of the replacement battery type.
> Since Lithium batteries require very special charging techniques, this
> is a matter that is not to be taken lightly.
> A simple replacement of the K2 SLA battery with another battery
> chemistry would have to be a redesign of the charging mechanism.

Don is of course right about simply putting in a battery with different chemistry.

But, there are LiFePO4 batteries with integrated controllers
specifically made so that they can be substituted for lead acid in
existing equipment.  Basically it has a charge controller for the
LiFePO4 that operates on the charging voltage for lead acid.  This item
replaces the 7Ah size; I don't know if there's an equivalent item for
the size in the K2.

http://www.amazon.com/A123-Systems-ALM-12V7/dp/B008VVO6LE/ref=pd_sim_sbs_328_12?ie=UTF8&refRID=0R6H1NBH31JQ509VCJ3V

(I have not tried this; I'm still a lead-acid using dinosaur.)

73 de n1dam

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Re: Alternative battery for K2?

Phil Wheeler-2
In reply to this post by TF3KX
I soon (12-13 years ago) decided I didn't want a
battery inside the K2 -- so it was removed and
only external batteries used. I was overly(?)
concerned about leakage and such issues. I'd have
the same, or greater, concerns with some of the
newer, higher-density batteries if inside my K2.

73, Phil W7OX

On 8/15/15 8:33 PM, TF3KX wrote:
> Hi everyone.
>
> Has anyone any experience or suggestions on replacing an aging internal K2
> battery (the standard lead-acid type) with one of the newer, lighter and
> more energy-dense batteries? I know there were some safety concerns with
> lithium-based batteries early on, but now that they are are used in all
> sorts of electronic gadgets, wouldn't there be some that would have the
> right form factor and voltage to fit in for the existing K2 battery?

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Re: Alternative battery for K2?

Chip Stratton
In reply to this post by TF3KX
I had a 4 cell LiFePO4 battery inside my K2 for quite a while. It was about
the same size as the original SLA.

I found that I was able to charge it with the built-in SLA charging circuit
as a matter of routine and the cells remained in balance, as verified by an
occasional balance charge with a CellPro Multi4.

The reason this worked well was because the cells in the pack were all of
good quality, the discharge rate was not excessive, the built-in K2 charger
charged at low current, and I was careful not to leave the charging circuit
on for prolonged periods. LiFePO4 will  tolerate limited low current
"overcharging" fairly well and without the danger associated with doing the
same with regular Li-Poly chemistry, and in my experience without damaging
the cells. Of course, ultimate cell life may be only 500 cycles instead of
the 2000 you might expect with good LiFePO4 cells and use of a quality
balance charger, but I never found any degradation.

I agree with others that have replied, however, that just using an external
LiFePO4 pack entails little disadvantage, and that is what I do now myself.

Chip
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