---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 02/06/19: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:58 PM - Re: Re: Battery (skywagon185guy) 2. 04:37 PM - Re: Re: Battery (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 12:58:47 PM PST US From: skywagon185guy Subject: Re: AeroElectric-List: Re: Battery If. . . the solar panel is a low current variety, say 1 amp or less, I believe a simple zener diode across the output, at the right voltage, will just clip the voltage at what ever it chosen...Thus, no over charging of a full charged battery. On Tue, Jan 22, 2019 at 6:12 PM Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > At 07:44 PM 1/21/2019, you wrote: > > I learned today from EarthX that they are ok with using a small solar > charger to charge their batteries, as long as it will NEVER exceed 14.6 > volts. Their emphasis, not mine.They also stated that many solar units > commonly are 15 volts or more and therefore not to be used with their > batteries. > > > Virtually ALL solar arrays offered to charge > 12v batteries will have a full-sun, open-circuit > voltage in excess of 16 volts. > > The 'small' arrays also have a rather large > internal impedance . . . meaning that the > output voltage falls off as load is increased. > But as any battery being charged with a 'barefoot' > solar array achieves full charge, flow of current > into the battery is not moderated. > > The short story is that any solar array > being considered needs to have a significant > current capability . . . the wall-wart maintainers > are good for about 0.8A and WILL eventually > top off a rather large battery. > > But to deliver 0.8A under marginal sun-light > conditions, the full-sun capability needs to > be 2x to 3x that amount . . . say 2.5A at > 14 volts or about 35 watts. > > Those cute little solar panels with cigar > lighter plugs are good for about 1-2 watts > and will MAINTAIN a fully charged battery. > But it takes a more robust device to serve > as replacement for the ship's engine driven > power source . . . i.e. top off a partially > discharged battery while hangared. > > The more robust arrays need some form of > electronics to keep their full-sun performance > from beating up an already full-charge battery. > > Bob . . . > ________________________________ Message 2 _____________________________________ Time: 04:37:01 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Battery At 02:57 PM 2/6/2019, you wrote: >If. . . the solar panel is a low current variety, say 1 amp or less, >I believe a simple zener diode across the output, at the right >voltage, will just clip the voltage at what ever it chosen...Thus, >no over charging of a full charged battery. Possibly . . . but what target votlage? If you're asking the solar array to mainatain a fully charged battery, then indeed a 13.0 volt zener would proably do. But this thread started as an exploration of using solar power sources to CHARGE the battery in an airplane with no engine driven power source. In this case, you need to clamp off at 14.5 for a top-off interval and the drop to the 13.0 sustaining voltage. Further, charging a battery probably calls for something larger than a 100mA solar array . . . Presumably, the solar battery smart charger module cited earlier will hat-dance to the right tune. Got on on order. Bob . . . ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.