[Elecraft] K2 Battery Life?

[Charles Greene]

Hi All,

My battery is still as good as new, and I bought it with K2 462 in 1999.  I 
have a Power Sonic automatic battery charger, and whenever the power is on 
in the shack, the automatic charger keeps it on float.  The automatic 
charger is connected to the battery directly through a fuse, and I keep the 
battery switch off unless I want to operate on the battery.  The K2 
normally operates from a 13.8 VDC supply.  I figured that to float the 
batter at only 13.8 volts might shorten its life.  I tried the automatic 
charger feeding the K2 power plug with the excess current coming out of the 
battery on transmit, but the automatic charger has some real bad hash on 
its output which gets into the K2 audio.  You can see it on a scope.  The 
hash gets filtered out by the battery (the battery is just a very large 
capacitor) when the automatic charger is connected directly to the battery 
with the battery switch on.  That way, the K2 can operate on the battery 
with the excess current coming out of the battery on transmit.  What is not 
good about this setup with the battery switch closed, is that when the K2 
is on, the receive current fools the battery charger into thinking the 
battery is partially discharged, and it goes into a charge mode.  It may 
overcharge the battery, again shortening its life.


At 10:21 AM 12/3/2003, Don Wilhelm wrote:
>Jeff,
>
>You may have been undercharging your internal battery, or may have subjected
>it to several deep cycles - both conditions will shorten the life of an SLA
>battery.  My battery is a 'real' PowerSonic and was new when I bought it.
>If you bought a 'pull-out' battery, you have likely gotten the expected full
>service from it.
>
>My inernal battery has been going strong now for almost 3 years - but it has
>never been deep cycled, and it is constantly topped off by my SmartCharger
>when it is in the shack.  I use a fused direct connection from the
>SmartCharger to the battery - you can look at the SmartCharger on my website
>(www.qsl.net/w3fpr) to see how I accomplished the connection.  I used the A
>& A SmartCharger and modified it for 250 ma output, but Bob Lewis had a
>slightly different charger (specifically for the K2) in a QST article a year
>or so ago. As my fuzzy memory reaclls board and perhaps a kit of parts is
>available should you chose to use Bob's design.
>
>73,
>Don W3FPR
>
>----- Original Message -----
>
> > How may months should the internal battery in a K2 last?
> >
> > My second battery has gone bad after 18 months in service. I have been
>very
> > careful to keep it on constant float charge at 13.9 V out of the charger.
>I
> > have the new low drop diode installed.
> >
>
>
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73, Chas,  W1CG
K2 462b, 3571