K2/100 Power Requirements

[John Lucas-2]

Anyone know from experience how long a 75 amp hour marine battery will last
in typical contest conditions running SSB K2/100W?

Thanks

John
[hidden email]


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[Thomas Beltran]

Actually, I had a question that is in a similar vein.  

I bought a buddipole, and plan on taking my K2/100 camping.  I began to
research batteries, such as gell cell and glass matt batteries, and solar
charging.  My guess is that I might operate about 4 to 5 hours per day,
running up to the full "gallon."  Operating modes would be SSB, CW and while
my laptop batteries held up, PSK.  I also plan on being out in the woods for
probably a week at a time.  

There is so much on the web, I just cannot separate out what would work,
from overkill.  In spite of reading several treatises, I still am not sure
whether I would want a gell cell or a glass matt battery.   My question
(finally) - I'd like to hear from people on the list who have a
battery/solar recharging system that works well and will run the K2/100 for
the 4 to 5 hours per day, listing the components he or she is using.  

Given the size and weight of batteries, I had hoped to use a 36 Ah battery,
and then recharge it with solar power.  But it seems that these batteries
charge rather slowly, and that might not be possible.  For example, I think
it is powerportstore.com that has a 1.2 amp flexible solar panel recharger
that puts out approximately 5.6 - 7 Ah per day.  The solar panel is about $
500.00.    The general size/weight and price is ok, but it doesn't appear
that such output would be sufficient to fully recharge a big battery.

I think I'd rather duplicate what has worked for someone else, than try to
reinvent the wheel.    Thanks in advance.  Tom W6EIJ


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[G3VVT]

 
In a message dated 03/06/05 04:10:11 GMT Daylight Time,  
[hidden email] writes:

Given  the size and weight of batteries, I had hoped to use a 36 Ah battery,
and  then recharge it with solar power.  But it seems that these  batteries
charge rather slowly, and that might not be possible.  For  example, I think
it is powerportstore.com that has a 1.2 amp flexible solar  panel recharger
that puts out approximately 5.6 - 7 Ah per day.  The  solar panel is about $
500.00.    The general size/weight and  price is ok, but it doesn't appear
that such output would be sufficient to  fully recharge a big battery.



Reply: ------------------------------
 
The problem of recharging the battery from the 1.2A solar panel (about 16  
-18W capacity) is related to the solar panel being rather lacking in capacity  
and would not do much more than delay the battery being run  down considering
the drain of a K2/100 on TX. It all depends on the TX to  RX ratio used with
the K2/100 and the mode of usage to how long the battery  will last. RX is no
problem with the K2 as that is in the 0.25A range, but the  100W on TX can draw
something in the region of 20A at full output.
 
However a 1.2A solar panel would be very usable with a basic K2 which has  
much lower TX current requirements of usually 2.0 to 2.5A at 13.8V. Even with  
this a charging controller would probably not be needed as the battery would  
provide much of the needed voltage regulation. A diode would be needed in  
series with the solar panel to prevent the battery discharging back into the  
panel when the solar insolation is insufficient to provide any charge.  This diode
is provided internally with most of the larger solar  panels.
 
For use with a K2/100 a much larger solar charging capacity would be  better,
probably in the 55W range (4A at 13.8V) or higher together with a  suitable
charge controller to prevent any possible over charging of the battery  and
consequent over voltage being applied to the K2/100.
 
With the solar powered communications systems I was involved with from 1981  
to 2002, these initially used multiple 55W panels (approx 3ft x 1ft) with  
individual controllers on each to provide the charging for the battery plant.  
Later 15kW systems used 200 x 75w panels (approx 4ft x 1.5ft each  panel) and
switched the solar panels in banks controlled by an intelligent  charger system.
A matter of balancing the required charging voltage  with the amount of
panels on line. This was needed to provide for the current  drain of the comms
systems and allow for days when the sun did not appear,  where the available
charging current would be insufficient to balance the  24 hr drain. With the latter
systems running a microwave site it was normal to  see 120A or greater charge
current at 54 to 58V when the battery  plant was in the morning full charge
cycle.
 
Bob, G3VVT
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[Charles Greene-2]

Bob,

My experience with a marine battery about that size in my sailboat with a
solar charger with a regulator was it the battery stayed topped off all
summer.  TWithout the regulator, it would overcharge.  Also, shop
around.  I only paid $80 for my 1 amp flexible solar charger a few years
ago.  BTW, I am using a 45 AH old car battery right now with my K2 and
K2/100.  A 6 watt wall wart keeps it topped off for the K2 with average use
but it needs some more for the K2/100.  I use a 6 amp PS which is what I
have, but a 2  or 4 amp is probably enough for occasional use of the k2/100.

At 06:44 AM 6/3/2005, [hidden email] wrote:

>
>In a message dated 03/06/05 04:10:11 GMT Daylight Time,
>[hidden email] writes:
>
>Given  the size and weight of batteries, I had hoped to use a 36 Ah battery,
>and  then recharge it with solar power.  But it seems that these  batteries
>charge rather slowly, and that might not be possible.  For  example, I think
>it is powerportstore.com that has a 1.2 amp flexible solar  panel recharger
>that puts out approximately 5.6 - 7 Ah per day.  The  solar panel is about $
>500.00.    The general size/weight and  price is ok, but it doesn't appear
>that such output would be sufficient to  fully recharge a big battery.
>
>
>
>Reply: ------------------------------
>
>The problem of recharging the battery from the 1.2A solar panel (about 16
>-18W capacity) is related to the solar panel being rather lacking in
>capacity
>and would not do much more than delay the battery being run  down considering
>the drain of a K2/100 on TX. It all depends on the TX to  RX ratio used with
>the K2/100 and the mode of usage to how long the battery  will last. RX is no
>problem with the K2 as that is in the 0.25A range, but the  100W on TX can
>draw
>something in the region of 20A at full output.
>
>However a 1.2A solar panel would be very usable with a basic K2 which has
>much lower TX current requirements of usually 2.0 to 2.5A at 13.8V. Even
>with
>this a charging controller would probably not be needed as the battery would
>provide much of the needed voltage regulation. A diode would be needed in
>series with the solar panel to prevent the battery discharging back into the
>panel when the solar insolation is insufficient to provide any
>charge.  This diode
>is provided internally with most of the larger solar  panels.
>
>For use with a K2/100 a much larger solar charging capacity would be  better,
>probably in the 55W range (4A at 13.8V) or higher together with a  suitable
>charge controller to prevent any possible over charging of the battery  and
>consequent over voltage being applied to the K2/100.
>
>With the solar powered communications systems I was involved with from 1981
>to 2002, these initially used multiple 55W panels (approx 3ft x 1ft) with
>individual controllers on each to provide the charging for the battery
>plant.
>Later 15kW systems used 200 x 75w panels (approx 4ft x 1.5ft each  panel) and
>switched the solar panels in banks controlled by an intelligent  charger
>system.
>A matter of balancing the required charging voltage  with the amount of
>panels on line. This was needed to provide for the current  drain of the
>comms
>systems and allow for days when the sun did not appear,  where the available
>charging current would be insufficient to balance the  24 hr drain. With
>the latter
>systems running a microwave site it was normal to  see 120A or greater charge
>current at 54 to 58V when the battery  plant was in the morning full charge
>cycle.
>
>Bob, G3VVT
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

73,  Chas,  W1CG

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