EternityForest
Member
Ebay has a ton of these constant current regulator things that they occasionally market as solar charge controllers, which I would imagine you would use with a lead acid or as a CC-CV charger with a lifepo4 single cell. I have a few of the constant voltage only lm2596 ones and they work well enough.
But has anyone actually used these for solar battery charging? Specifically, I'm curious about the brownout characteristics, and if there is any possibility of long-term damage happening due to undervolting the converter for long periods(Which will no doubt occur during sunrise and sunset, probably for several hours a day)
Nowhere in the datasheet is anything about brownouts mentioned, except a note on how to make a power up delay because "some circuits" need to avoid turning on until power is stable, implying that the regulator itself is just fine or at least not seriously angry about brownouts.
In the testing I've done(with the non-constant current version), it seems that they have a fairly "linear regulatorish" dropout, where they will continue to provide whatever voltage they can even when the input is below the output setpoint, slowly tapering to 0V output at about 2.0v input, and I assume most SW regs are like this, because I haven't seen any(Except really fancy ones) that aren't, so no issue there, the reg will regulate whatever the panel can provide.
In this shutdown state(Unsure if caused by the IC or by the module design), if a 3.2v battery is connected to the output, they will draw ~12mA in backpower from the battery, meaning at least with the modules I have, a diode(Probably a FET active diode if charging a 3.2v cell) is needed to prevent discharging the cells(And possibly harming the regulator?)
The voltage accuracy is pretty good, and I always charge lifepo4 to less than full anyway, and lifepo4 is pretty safe especially with a protection PCB.
A lot of the cheap boards seem to have what appear to be shoddy looking capacitors that are rated to only 35v, giving you absolutely no safety margin at the full 35v the regulators claim to be able to handle, which shouldn't be an issue with ~17v solar panels.
What do you guys think? Anyone ever used these? I'm interested in building a small portable solar system, with about 15-50W maximum capacity, and maybe 100Wh battery capacity, just for basic stuff like charging cellphones and flashlights and powering low power radio gear if I ever get off my butt and get my license and a rig...
**broken link removed**
**broken link removed**
But has anyone actually used these for solar battery charging? Specifically, I'm curious about the brownout characteristics, and if there is any possibility of long-term damage happening due to undervolting the converter for long periods(Which will no doubt occur during sunrise and sunset, probably for several hours a day)
Nowhere in the datasheet is anything about brownouts mentioned, except a note on how to make a power up delay because "some circuits" need to avoid turning on until power is stable, implying that the regulator itself is just fine or at least not seriously angry about brownouts.
In the testing I've done(with the non-constant current version), it seems that they have a fairly "linear regulatorish" dropout, where they will continue to provide whatever voltage they can even when the input is below the output setpoint, slowly tapering to 0V output at about 2.0v input, and I assume most SW regs are like this, because I haven't seen any(Except really fancy ones) that aren't, so no issue there, the reg will regulate whatever the panel can provide.
In this shutdown state(Unsure if caused by the IC or by the module design), if a 3.2v battery is connected to the output, they will draw ~12mA in backpower from the battery, meaning at least with the modules I have, a diode(Probably a FET active diode if charging a 3.2v cell) is needed to prevent discharging the cells(And possibly harming the regulator?)
The voltage accuracy is pretty good, and I always charge lifepo4 to less than full anyway, and lifepo4 is pretty safe especially with a protection PCB.
A lot of the cheap boards seem to have what appear to be shoddy looking capacitors that are rated to only 35v, giving you absolutely no safety margin at the full 35v the regulators claim to be able to handle, which shouldn't be an issue with ~17v solar panels.
What do you guys think? Anyone ever used these? I'm interested in building a small portable solar system, with about 15-50W maximum capacity, and maybe 100Wh battery capacity, just for basic stuff like charging cellphones and flashlights and powering low power radio gear if I ever get off my butt and get my license and a rig...
**broken link removed**
**broken link removed**
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