KX3 clock & battery. (Was KX3 clock will not set from KX3 utility)

[Elecraft mailing list]

Hi All.

Regarding the KX3's clock and battery functions.

Am I right in recalling that the clock will run from External power, not
pulling the battery down, if external power is available when the rig is
turned off?

If so, mine has an issue, as even with 24/7 external power (13.5V) when
the rig is "Off", it will drain the internal batteries down to near zero!

I have to periodically power the rig (if not regularly used) and
recharge the batteries as a result.

Is this "normal", or ???

73.

    Dave G0WBX.


On 27/11/17 01:32, [hidden email] wrote:

> Subject: Re: [Elecraft] KX3 clock will not set from KX3 utility
> Message-ID: <[hidden email]>
> Content-Type: text/plain; charset=utf-8
>
> There is a timer in the KX3 that starts at zero when turned ON.  You can set this to current time and it will serve as a clock until radio is turned OFF.
>
> Adding the charger option with internal batteries provides constant power to the timer to provide Real Time Clock function.
>
> Sent from my iPhone
> ...nr4c. bill

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[Bob N3MNT]

Something is not right.  I am using eneloops and can go many months between
charges ( usually only top off charges) and my power supply if off when the
rig is not is use.



--
Sent from: http://elecraft.365791.n2.nabble.com/
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[Elecraft mailing list]

Re:  "...even with 24/7 external power (13.5V) when the rig is "Off", it will drain the internal batteries down to near zero!"

One problem is that you now have damaged cells since they have been discharged to below 1 volt per cell.  I suggest you stop trying to troubleshoot your radio with damaged cells.  

Install a fresh set of low self discharge (LSD) cells and watch voltage daily until you have confidence that the voltage is staying constant.  I recommend Eneloops since mine have worked so well since I installed them in early 2013.  The voltage should remain constant for months once it has dropped to 1.2v per cell (1.2 x 8 = 9.6v).

Sometimes my KX3 sits in my go pack with no external power for months.  Other times it sits on the desk connected to a 13.8v supply.  With Eneloops installed, I have not seen the discharge rates you have.

I did experience similar discharge rates once when I tried a set of Energizer cells.  They were not LSD, however.  I quickly took them out and reinstalled the Eneloops.

In response to your original question concerning clock (KXBC3) power source:
I haven't looked at the schematic for a long time, but as I recall, the radio, including the KXBC3, are powered by the higher of the internal battery or external power voltages.  The radio portion is turned on and off by a MOSFET, but the KXBC3 is tapped off upstream (closer to the battery/power plug), so it can continue operation after radio shutdown.  This suggests that if your KX3 has external power applied and the battery is discharging, it is MOST LIKELY due to cell self discharge and NOT the radio or charger.  So do yourself a favor and install a new set of LSD cells.

Mark,
KE6BB

null
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