On 28 May 2013 at 12:00, [email protected] wrote: > From: Greg Troxel <[email protected]> > To: [email protected] > Subject: Re: [Elecraft] KX3 and Solar Panel > > A 20W panel that is labeled as for a "12V" system will typically have > a Voc (open circuit) of 22ish V, and a Vmp (maximum power voltage) of > 18V. > > Generally, one should not hook up a bare panel to a load, and the > usual recommendation is charge controller and battery. I wonder > about a large cap instead of a battery, enough to make the controller > stable. > > I have a 20W (HQRP) panel and use a Genasun GV-5 MPPT charge > controller and then charge about 100Ah of batteries. I have not tried > the controller with no batteries. > > The anyvolt3 is an interesting concept for this application. MPPT > controllers try different voltage/current combinations to find the one > that's in-range for the DC-DC converter and results in maximal power. > I have found that to be around 17.5-18V whenever I get more than 200 > mA >From the system (sometimes I see 1.6A). The anyvolt3 is expecting > a voltage source, it seems, and the datasheet seems to imply that. A > panel is not a voltage source. So I really wonder what would happen. > Has anyone put a high-speed scope on the input when hooked up to a > panel?
MPPT controllers are usually switch-mode regulators with special control algorithms, and are notorious HF noise generators! Take care, you may need lots of filtering, on both the "regulated" DC out, *AND* the Solar DC input. They are also designed (as you rightly say) to work with a battery bank, and would almost certainly be "unhappy" with a light to non existent load, especially one that varies a lot over a short time scale, as a SSB or CW transmitter does. For portable HF radio battery-less use, a linear series regulator, or more likely a parallel shunt regulator would be best. Inefficient true, but quiet!. 73. Dave G0WBX. ______________________________________________________________ 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
