[Elecraft] Can I overcharge the batteries in my KX3

[Mark Petiford]

First of all, forget the Nicads.  The KX3 isn't really designed for Nicads, and they have a lot of problems such as excessive self discharge, and leakage.  If you want rechargeable cells, use modern low self discharge (LSD) nickle-metal hydride (NiMH) cells.  Eneloops are one example, and probably the most popular.  The KX3 manual discusses the use of them in the Internal Batteries section.  Usually LSD NiMH cells are sold in a charged condition.  Once installed, they can sit in your radio for long periods losing very little of their charge.  I have never seen a modern NiMH cell leak, unless they are discharged to less than 1.0 volts per cell.  The KX3 prevents this with its adjustable battery warning and automatic shutdown.


Assuming you are using LSD NiMh cells of at least 2000mah in size.  The KXBC3 charger is a 200ma - 250 ma (approx.) constant current charger which is about 0.1 times the capacity of the cells.  That is a perfect constant current charge for 2000mah cells or larger.  Cell manufacturers' guidelines for these cells state that is isn't likely that you will overcharge using this method but they suggest you not leave the charge on constantly like you would when using a trickle charger.  (A trickle charge rate would be about 1/4th of the KXBC3 charge rate, if my memory is correct).  Since the KXBC3 also monitors cell temperature, it complies with the manufacturers' recommendations.  It will only charge while the cell temperature is within limits, and will suspend charging until the temperature returns to normal.

In reality, MiMH cells work best when charged somewhat longer than necessary.  That allows the lowest charged cells to be brought up to a fully charged condition.  They are self-leveling.


Mark
KE6BB   

    On Thursday, May 4, 2017 3:40 PM, Jerry <W1ie at jetbroadband.com> wrote:
 

 Hello,

 

I am about to take a month long trip to California and then back to Virginia
starting this Sunday. I am taking my KX3 along with some accessories so I
would like to know - is it possible to overcharge the NiCads or Enloops. I
have a system set up on my motorcycle that will provide 13.8vdc at 3 amps
clamped.  for charging some 12 v sealed lead batteries and I am wondering if
I use this output voltage and set the timer to 8 hours on the KX3 charging
system, can I overcharge the batteries and ruin them or worse the internals
of the KX3?

 

Thank you.

 

Best regards,

 

Jerry, W1IE

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to rv6amark at yahoo.com