The charger could in theory be redesigned to work with a 12.8-V LiFePo4 pack (4 cells), but there are several disadvantages to this:
- AA LiFePo4 cells appear to have a rating of about 600 mA-hours. As a coarse metric, 4 cells at 13 V would provide about 7.7 watt-hours, which is very poor compared to 8 NiMH cells; the NiMH pack rovides roughly 2500 mA hours at 10 V, or 25 watt-hours. There's room for 8 cells, so NiMH makes better use of the existing space. - Even though you'd get 13 V from LiFePo4 cells, and could thus run full power, you'd only be able to operate for a third as much time (roughly). The KX3 can put out as much as 5 W from 10 V, and since this is only 3 dB down from full power, it's probably a better trade off for a weekend of casual operation. Your antenna and propagation will generally outweigh this 3 dB power factor. - Being able to use just about any type of AA cells in a pinch is important for ad-hoc field use of the radio. You can then borrow AA cells from other devices in an emergency. So if you used 4 LiFePo4 cells, you'd want to leave the other socket in place and insert some sort of placeholder cells (easy to lose) or a bypass switch. - LiFePo4 cells are not as readily available. You can get NiMH cells a drug stores, supermarkets, Radio Shacks [before they close], etc. Wayne N6KR On Feb 11, 2015, at 1:03 PM, Jim Wilkie <[email protected]> wrote: > Andt, will wait for the experts to answer, but I think the nimh charger vs > the lopo charger would be a problem. > > Jim Wilkie WY4R > > > On 2/11/2015 2:18 PM, Henshaw, Andy wrote: >> Has anyone looked into hacking a replacement battery case for the KX3 that >> featured LiFePo4 cells? I've seen external LiFePo4 packs being used, but it >> seems like an internal solution might be workable. With a 13.2V supply >> (four cells in series), one can run the KX3 in full-power mode. In >> addition, the discharge curve of LiFePo4 is much better than NiMH. >> >> I'm asking, because I'd like to take my KX3 on some backpacking trips and it >> just seems wasteful (of space) and slightly awkward (for setup) to have to >> carry an external battery pack in order to get full-power. >> >> It appears that AA size LiFePo4 cells are available. So, wouldn't it be >> feasible to arrange them in a 4S2P configuration that could replace the >> existing battery holder? >> >> Andrew Henshaw >> >> ______________________________________________________________ >> 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] ______________________________________________________________ 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]
