[Elecraft] FD2004: Solar K2 w/Li-Ion

Wed Mar 17 19:14:01 2004

Hi

According to Maha the maker of Powerex brand NiMh batteries the new =
generation of batteries this is not a problem. In fact Thomas =
distributing says it is ok to leave the batteries in the charger =
indefinitely. I have a product I manufacture that has a 9 volt NiMh =
battery in it that is permanently on a trickle charge at a about 1/10 C. =
I have over 25,000 of them in the field many in operation over 4 years =
and so far as I know I have never had a failure. This battery is only =
used when the power fails so it can have months of charging before a =
discharge cycle may be required. At any rate charging a battery pack =
from a solar panel that provides 1/10 to 1/5 C for a day or two will not =
be a problem. It is unlikely that the panel will be able to supply its =
full rated power all the time because of clouds and the changing angle =
of the sun and you will only get about 8 hours of charging. Another =
factor is if you are also running the K2 then the power into the =
batteries is reduced. You can monitor the battery voltage with the K2 =
and disconnect the panel if the batteries look to be at full charge if =
it really worries you. The goal is to have enough power to operate the =
k2 overnight and then recharge the batteries during the day while =
operating.

Don Brown
KD5NDB

----- Original Message -----=20
  From: John Buck<mailto:[email protected]>=20
  To: Don Brown<mailto:[email protected]>=20
  Cc: [email protected]<mailto:[email protected]> ; =
[email protected]<mailto:[email protected]>=20
  Sent: Wednesday, March 17, 2004 3:53 PM
  Subject: Re: [Elecraft] FD2004: Solar K2 w/Li-Ion

  Unless my information is obsolete, NiMh batteries will be ruined by=20
  trickle charging indefinitely at 1/10 C.  The recommendation quoted=20
  below is good for NiCad but is not valid for NiMh.  The NiMh =
application=20
  notes that I have clearly state that even low rates of overcharge will =
=20
  kill the NiMh Battery.  This is the principle reason that old nicad=20
  chargers are not recommended for use on NiMh batteries.

  Is there new information available of which I am unaware?

  Yes you can charge the NiMh batteries with a small uncontrolled solar=20
  panel.  But you must watch the voltage and be sure to disconnect the=20
  charge source when the battery nears full charge.

  John KH7T

  Don Brown wrote:

  >You can charge NiMh batteries with a small solar panel without a =
controller. I am assuming you want to run a K2 not a K2/100. 10 AA 2200 =
ma/hr cells can be charged with a 5 to 10 watt panel and power your K2 =
at the same time. These batteries can be left on charge at 1/10 C =
indefinitely without damage. A 5 watt panel will supply about 320 ma, =
just a little above the 1/10 C rate for a 2200 ma battery.
  >snip
  >

  _______________________________________________
  Elecraft mailing list: =
[email protected]<mailto:[email protected]>
  You must be subscribed to post to the list.
  To subscribe or unsubscribe see: =
http://mailman.qth.net/mailman/listinfo/elecraft<http://mailman.qth.net/m=
ailman/listinfo/elecraft>
  Elecraft Web Page: http://www.elecraft.com<http://www.elecraft.com/>
  Also see: =
http://www.elecraft.com/elecraft_list_guidelines.htm<http://www.elecraft.=
com/elecraft_list_guidelines.htm>

--- StripMime Report -- processed MIME parts ---
multipart/alternative
  text/plain (text body -- kept)
  text/html
The reason this message is shown is because the post was in HTML
or had an attachment.  Attachments are not allowed.  To learn how
to post in Plain-Text go to: http://www.expita.com/nomime.html  ---