A silicone diode instead of a schotkey would probably do it, though voltage may be a little on the high side if you’re expecting the panel to be very cold when the battery is full
Sent from Mail for Windows 10 From: Peter VanDerWal via EV Sent: Wednesday, 3 June 2020 1:21 AM To: Electric Vehicle Discussion List Cc: e...@vanderwal.us Subject: Re: [EVDL] Question about charging small LiIon batteries Now why didn't I think of that? The chargers I've been looking at have MPTT(or at least they claim to), however I could just use two panels. I have a couple dozen panels left over from an abandoned project: 5V @ 240ma, they have conformal coating so reducing them to 5 cells instead of 6 would be difficult. However, I could run a couple diodes in series... June 2, 2020 10:02 AM, "Matt via EV" <ev@lists.evdl.org> wrote: > What about no charge control, a solar panel whose Voc is 4.5v (so only 5 > series cells) and a > schotkey diode to prevent back flow > > That would have the effect of limiting max voltage to ~4.2v, but at 4v only > around 20% of Imp would > flow (ie charge rate slows right down past 3.6v) > > How much power are you thinking? > > Sent from Mail for Windows 10 > > From: Peter VanDerWal via EV > Sent: Wednesday, 3 June 2020 12:55 AM > To: Electric Vehicle Discussion List > Cc: e...@vanderwal.us > Subject: [EVDL] Question about charging small LiIon batteries > > Somewhat off topic, but I'm hoping someone can help. > > I'm building a solar powered weather station and plan to use 1 or 2 18650 > cells. There are tons of > small solar chargers available for these, however they all charge the cells > to ~4.2V. > To maximize life from the LiIon batteries I'd like to keep them between > 40-80% charged. > > So what I'm looking for is either a solar module that I can set to only > charge the cells to ~3.9V > or a way to make a 4.2V charger work. > Since I'm not having any luck finding 3.9V chargers what I've been thinking > about is perhaps using > a schottky diode to drop the 4.2V to around 3.9V. however that would prevent > the charger from > seeing voltage from the battery and it might not start charging. > So I'm thinking maybe putting a 100 ohm resistor in parrel with the diode, > that would allow the > charger to see the battery voltage. > I still have to figure out how much current the microcontrollers, etc. will > draw, but it's going to > be at least 10 mA when idle, with bursts up to several hundred ma when > transmitting. > > Does this sound like a reasonable plan? Any better suggestions? > > Thanks, Pete. > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200602/3cd29a40/attachment.html> > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/index.html > INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200603/9de4e27d/attachment.html> > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > ARCHIVE: http://www.evdl.org/archive/index.html > INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20200603/429c62d6/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
