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, [EMAIL PROTECTED] wrote:
In a message dated 03/06/05 04:10:11 GMT Daylight Time,
[EMAIL PROTECTED] 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: [email protected]
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
_______________________________________________
Elecraft mailing list
Post to: [email protected]
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
