[Elecraft] K2 Battery Shelf Life - Resolution - A New Question

Fri Jan 30 18:01:00 2004

Just tried the battery load test recommended below. Thanks Albert!

With the DMM measuring the voltage across the battery terminals:
K2 Receive   0.24 amps  12.4 volts.
K2 Transmit  2.44 amps  11.7 volts.
K2 Transmit  3.14 amps  11.5 volts.
K2 Transmit  3.58 amps  11.4 volts.

The current was measured with the K2's built in ammeter.

The battery would always recover within a few seconds to 12.4 volts on
receive.

So it takes about 3.5 amps for the battery voltage to drop by 1 volt.

>From the graphs on the battery datasheet, it looks like my battery's
voltage is about 0.3 or 0.4 volts low at the test current levels. The
graphs show that the voltage should change from about 12.7 volts at 0.24
amps to 11.6 volts at 3.6 amps.

Battery experts, your opinions please.

Darrell Bellerive
VE7CLA  K2 #1973

On Fri, 2004-01-30 at 11:18, Albert Heyes wrote:
> Hello Darryll
>    I have missed other answers to you, but reading this mail suggests the
> battery me have a high internal resistance. To check turn the rig on with a
> dummy load or antenna connected push you key down to give say about
> 10 watts out then measure the battery volts. This rading is the battery PD
> (potential difference) the reading you have already measured is the
> EMF(electro motive force)  a digital mulitmeter has a very high impedence
> and demands almost no current. A volt drop of over a volt suggests the
> battery has a slightly high internal resistance Eg 0.6 ohms a good battery
> would be around 0.1 ohms.
>    Have fun Darrell from [email protected]
>            73  albert
> 
> 
> ----- Original Message ----- 
> From: "Darrell Bellerive" <[email protected]>
> To: "Elecraft Email List" <[email protected]>
> Sent: Friday, January 30, 2004 6:46 PM
> Subject: Re: [Elecraft] K2 Battery Shelf Life - Resolution
> 
> 
> > Thanks to all who replied to my message. You have been a big help.
> >
> > The battery appears to be in good health. This comes as a welcome relief
> > after reading in the KBT2 manual that the battery had a shelf life of
> > only one year.
> >
> > Following the directions on the datasheet from the battery manufacturer,
> > the battery was charged until the 29 ma current flow was achieved. This
> > occurred at 14.2 volts, a bit lower than spec. Floating the charge at
> > 13.80 volts for 24 hours resulted in a battery that will maintain a full
> > charge of over 12.9 volts after 4 hours without charge current. At 24
> > hours after charging the voltage was still 12.84 volts.
> >
> > Perhaps some of the capacity has been lost, but for my occasional
> > battery operation of the K2 it should be fine.
> >
> > Thanks again for all the help.
> >
> > Darrell Bellerive
> > VE7CLA
> > K2 #1973
> >