The 4.2V is the maximum open circuit voltage. If you are that worried about it only use 3 Li-ion batteries.
Adding a couple of 5A diodes in series is a viable option as well, plus it adds the reverse voltage protection. Keith KB9WMJ ----- Original Message ----- From: "Chip Stratton" <[email protected]> Cc: <[email protected]> Sent: Sunday, July 13, 2014 6:10 PM Subject: Re: [Elecraft] My KX3 Battery Approach The 3.7V rating is its voltage at about 50% state of charge. That type of Li-ion cell has a fully charged voltage of 4.2V. Four of them would be too much for a KX3. Chip Ae5ka On Sunday, July 13, 2014, <[email protected]> wrote: > Use a better AA battery (3.7V 4.9AH Li-ion): > http://www.ebay.com/itm/181411959514 > > and battery holder: > http://www.utmfg.com/category/BAT-AA.html > > Use 4 of them for 14.8V. > > Keith > KB9WMJ > > > ----- Original Message ----- > From: "hb9brj" <[email protected] <javascript:;>> > To: <[email protected] <javascript:;>> > Sent: Saturday, July 12, 2014 12:30 PM > Subject: Re: [Elecraft] My KX3 Battery Approach > > > Using 8 internal eneloop cells, I measured battery voltage versus current > (as > shown on the KX3 display) during RX and different TX pwr levels, created > an > Excel scatter chart and fitted a linear trend line. The result: 1.15 Ohms, > R^2 = 0.95. > > A single eneloop cell has around 0.035 Ohms of internal resistance > (measured > with a 4-connector battery DC resistance meter forcing current pulses thru > the cell under test). > > My conclusion: 25% of the 1.15 Ohms are due to the 8 cells, 75% originate > in > the battery holder and additional wiring. > > Markus HB9BRJ > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] <javascript:;> > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] <javascript:;> > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
