Hi Hal, Thanks for the advice.
I believe the battery has a BMS that will cut off the output if the power draw is too high -- is that sufficient? If not, can I trust the fusing on a RIGrunner port, or should I get a proper inline fuse holder that covers both conductors? 73, Julie On Tue, Oct 19, 2021, 18:40 Hal Massey <[email protected]> wrote: > Hi, > > Your solution should work just fine. > > The Bioenno batteries I could look up easily were LiPO technology. I would > make one suggestion when using a technology like LiPO. Turn off the charger > every now and then and deplete the battery down to say 25%. You can > accomplish this with a simple mechanical timer on the AC line (or use > something more sophisticated). LiPO manufacturers don’t show any data on > “Float Charging” which is what you propose. > > The reason I say this is I cannot find an exact replica of your suggested > usage model in any of the characterization data on any manufacturer of LiPO > batteries. Without a reliable source like data from a manufacturer you are > taking on some of the engineering. At worst I could see your battery life > being slightly shortened by your approach. > > LiPO batteries get intense when shorted out. I would recommend a fuse, > fusible link, or circuit breaker to keep an accident from turning into a > thermal event. Accidents do happen with power sources. > > The setup you are contemplating depends on integrating the charge demand > and charge resupply (recharging). So if you add a 100W final, an ATU, or > something else just be sure to keep that in mind. Every time you go beyond > a 4A current demand the battery will be supplying the difference until you > stop making greater than a 4A demand. Then the battery will return to > recharging. Of course if demand exceeds 4A for too long the voltage will > sag. > > > While this always sounds pompous when I read it I will supply my > credentials so you know this is not just a casual social media reply. I > hold a BSEE from the University of California at Santa Barbara, an MSEE > from Santa Clara University and practiced design engineering for over 35 > years ending up the Vice President and General Manager (GM) of Hewlett > Packard’s Business Critical Hardware Group (a $2 Billion US International > business). Having said all that I am not a battery expert. I looked at your > problem using engineering first principles. (Can it be done? Can it be done > safely? What are the consequences of such a topology?) > > I once float charged a 12VDC AGM battery from an Astron 50 Amp supply on > top of California’s Crystal Peak. Crystal Peak is 1 mile south and 1 mile > east of the famous Loma Prieta. Loma is famous for the big earthquake in > 1989 during the World Series Baseball Game). This setup worked quite > successfully for many years. Local hams told me it couldn’t be done and the > battery wouldn’t last. When power failed at Crystal Peak we remained on the > air (440.1--- N6ITW Repeater). It was true that the battery would not last > the full service life in the manual. But most hams cannott keep a repeater > running for 10 years with the same gear anyway. I suspect your experience > will be similar. This will not be the perfect charge/recharge profile for a > LiPO battery but it will be good enough. > > Regards > -Hal Massey (WB6NNR) > > > On Oct 19, 2021, at 14:16, Julia Tuttle <[email protected]> wrote: > > > > Hi, > > > > I've got a Bioenno battery (it's so good!) and the stock 14.64 V > (no-load, > > by my cheap meter) 4 A (claimed) charger. I'm currently planning to just > > leave things plugged in (mains to the charger to the battery to the > radio), > > and I want to make sure that's safe (won't start a fire and won't damage > > the charger, battery, or radio). > > > > Here's why I think it is: > > > > Will I overload the charger? No, the KX3 draws well under 4 A. If the > > battery is charging simultaneously, the constant-current circuitry will > > adjust the voltage down until the two loads together are drawing less > than > > 4 A, at the cost of lower charging speed, lower output power, and/or > higher > > PA heat dissipation. > > > > Will I overcharge the battery? 14.64 V works out to 3.66 V per cell, > which > > looks like it's about 93% state of charge, which is fine for the battery > > long-term. > > > > Will I overvolt the radio? No, 14.64 V is under 15 V. > > > > Am I missing anything here? Is this a safe way to leave things long-term? > > > > Thanks, > > > > Julie > > ______________________________________________________________ > > 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]
