Solar Charger

[KR4OW]

Hello all. I just installed the KBT2 battery kit in my
K2. I have a 5 watt unisolar flex panel that I would
like to use to charge/run the K2 with especially for
field day, portable, etc...
My panel puts out 17.5 volts no load at a rated 5
watts according to the company. I read in the KBT2
Manual that the the current control is done by the
6.2ohm/2watt resistor. which should handle any typical
power supply So I would think. Does this also apply to
the solar panel?? my thinking is that to start with
that the battery is only going to draw what it needs
to keep the charge. Is this Correct?? or is the higher
voltage an issue??
Thanks
David KR4OW
K2 4320

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around
http://mail.yahoo.com 
_______________________________________________
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

[Mike B-12]

David N. wrote:
> Hello all. I just installed the KBT2 battery kit in my
> K2. I have a 5 watt unisolar flex panel

Same setup here.

The design of the KBT2 does not regulate voltage - it just regulates a
small current to float charge the battery.  It's specifically designed
for an external, approximately 14 volt supply.

If you want to charge the 2.9 AH battery up fast, by all means you can
connect it directly to the PV panel, but you must monitor the battery
voltage as it will try to climb very high.  The voltage must be
regulated - a common method is to use a small charge controller such as
the Micro M+ from SunLogic (owned by a ham)
(http://www.seslogic.com/microm+.html) or Don Brown (I think that's the
fellow - he offered it here again just in the last day or two).

My older Micro M is external - I used one of the transverter holes to
add a coaxial jack, clearly separated from the main power, that runs
direct to the battery.  The charge controller has to bypass the resistor
and diode included in the KBT2 kit and see the battery directly.  I've
heard that others have added the Micro M internally to the K2 lid, but I
haven't seen one.

Some hams also have used a zener diode to clamp the voltage down.  This
means, however, that the zener must dissipate the excess power, and may
get warm.  I've never tried this method.

Hope this helps.

--
73,
Mike Boice, KW1ND
Karns, TN
Behold the power of the penguin
Reclaim Your Inbox!  http://www.mozilla.org/products/thunderbird/

_______________________________________________
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