I've had pretty bad luck with MP2307 boards, a lot of them that I use are defective. The LM2596 boards I've used have all worked however, they use the much better 10-turn potentiometers. You could try and replace the variable resistor with your own potentiometer or fixed one, it is a bit of a challenging rework since it's such a small SMD part. It won't have any current limiting either so it might not work very well, but I guess it's better than diodes.
- Justin On Tue, Jun 2, 2020 at 9:05 PM <[email protected]> wrote: > Justin Kenny's suggestion earlier reminded me of something, so I went > looking through my spare parts and found some regulators boards that have > variable MP2307 regulators. I originally got them to use with 3.3V > microcontrollers, but never used them because they have flaky outputs. I'm > pretty sure the problem with them is the cheap variable resistors, I think > if I replace those with a fixed voltage divider they might be ok. > > > However, I think the problem with them is the cheap variable resistors > they use > June 2, 2020 6:30 PM, [email protected] wrote: > > Peter, > Can i suggest a lm723 voltage regulator configured as a shunt regulator. I > have used the datasheet design with solar panels. Lee may be able to > recommend a better design than the barebones design in the datasheet. As > the solar panel is a current source of limited output you could probably > forgo the load resistor and simply dump all the excess energy into a large > enough power transistor. The standby current of the device is typically > 1.7ma with 30v source according to the datasheet so id expect it to be > lower in your application. The addition of an output diode would disconnect > the reg once the solar input was removed. > Regards, > Justin > On Jun 3, 2020 10:58, Peter VanDerWal via EV <[email protected]> wrote: > > Yes, Lee has already pointed this out, so I am looking into putting the > zener in parallel to the PV panel and then a schottky, etc. in series to > the battery. > > The problem I have with the cheap CV/CC circuits from china is that in my > experience they have a high failure rate and, just like buttered toast, the > failures tend to happen in the worst possible mode. > > June 2, 2020 3:17 PM, "Justin Kenny" <[email protected] (mailto: > [email protected]?to=%22Justin%20Kenny%22%20<[email protected]>)> wrote: > Not sure if you understood the previous 2 messages, the Zener diode will > drain your battery, and a diode will not stop it from overcharging. I > really suggest to use the right tool for the job, $3.25 for a > constant-current constant-voltage converter isn't much cost to save your > battery pack from being killed prematurely, or at worst preventing a > fire/destruction by overcharging: https://www.amazon.com/dp/B00LPK0IKQ ( > https://www.amazon.com/dp/B00LPK0IKQ) > - Justin > On Tue, Jun 2, 2020 at 2:57 PM <[email protected] (mailto: > [email protected])> wrote: I'm thinking of using two panels, one tilted > 45 degs to the east, and the other tilted 45 deg to > the west. That should provide a fairly flat power output through the day > with something like .375 > ma max. If I put a 4.3V zener across the panel, then that should bypass > some of the current, so I should only see a swing from perhaps 0.2V to 0.3V > and the 0.2V will likely occur when the panel voltage is lower. > At any rate a 0.1V variation is close enough for my purposes. > I've got a selection of diodes on order, so I'll see what happens when I > test it on the bench. > > Pete. > > June 2, 2020 1:51 PM, "jkenny23 via EV" <[email protected] (mailto: > [email protected])> wrote: > > > Another very important note; diodes don't drop voltage the same at all > > current levels. Meaning; they will NOT stop your 4.5V panel from > > overcharging your battery to 4.5V if you don't have a dedicated charging > IC. > > > > If you want to charge your battery to an unusual voltage, I highly > recommend > > using an adjustable CC/CV (constant-current/constant-voltage) buck > > converter. They're widely available from China on eBay and Aliexpress, > and > > probably available from the US through Amazon. This way you can set a > safe > > current limit (say 400mA), and a voltage limit that is lower than 4.2V > (say > > 3.9 or 4.0V). Then you could even use multiple panels in series and not > > worry about charging, the input limit for the common LM2596 modules is > 35V. > > > > Here's some data for a common 1N5819 Schottky diode illustrating the > issue > > of voltage drop as current tapers down at the end of charging: > > 1.0A - 0.41V > > 0.5A - 0.35V > > 0.1A - 0.28V > > 20mA - 0.23V > > > > -- > > Sent from: http://electric-vehicle-discussion-list.413529.n4.nabble.com > (http://electric-vehicle-discussion-list.413529.n4.nabble.com) > > _______________________________________________ > > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ( > http://www.evdl.org/help/index.html#usub) > > ARCHIVE: http://www.evdl.org/archive/index.html ( > http://www.evdl.org/archive/index.html) > > INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org ( > http://lists.evdl.org/listinfo.cgi/ev-evdl.org) > > Please discuss EV drag racing at NEDRA ( > http://groups.yahoo.com/group/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/20200602/9714388d/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... 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