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Why do I need a switch for a solar battery/usb charger? Answered

 I just browsed online and skimmed through other peoples' projects and failed to notice everyone using a switch. I then thought about it and my 4 solar cells where scavenged from lawn lights that used a light sensitive switch (can't think of the word at the moment). However I had already put my idea to work (without a switch) and I drained the batteries to around 1v a cell by charging my phone over night, and then I happily placed my charger out in the sun without anything hooked up via usb and when watching voltage it was going up at an ok rate. Well hours later I go back to check on it and the voltage dropped back down, now my cells are under 1v a cell. The solar panel is hooked up positive to the battery pack positive, there is a diode between, then after that connection a usb female connector is put in after that, and they are all grounded to the same line. I am confused as to where the batteries could have drained to, and why everything can't be in parallel, although I admit I am pretty newbish, but the logic still doesn't make sense to me.
Thank you for your time. (sorry the image looks like it was drawn b a 3 year old)


Can you post a circuit diagram, and the spec' of the cells, and the batteries?
It's hard to tell what you've really got here.


 Well the solar panels were stolen, they seem to each be 3v cells, but being in arizona when I have 2 in series they put out around 6.5v total. Which means I can't use a standard regulator.

Batteries I have 2 parallel sets of 4 NiMH AA cells rated at 2500mah. When I first put this together and put it in the sun I was charging at 5.03v, but I am guessing that was just the batteries

Sorry, as I said, I'm a newb at this and was trying to learn the hard way I guess, and now I am completely confused...


In that diagram your batteries are opposing each other - that ain't going to work.
Also NiMH should have controlled current & voltage, this is liable to damage them if it hasn't already.
For example if you search for "NiMH charger schematic"


Yeah, why are your batteries opposing each other??  They must all face the same way!

 I need a higher voltage, so thus they are in series. Otherwise I would be at around 1.2v

The idea is I have 3 chargers. A solar usb charger, a Batter usb charger, and a solar battery charger.

Here is a similar example, although like I said, they are using a switch that my newb mind thinks is pointless since all the power and ground wiring is all going the same direction...

Your diagram shows +[]--[]++[]--[]+
This isn't going to work, you'd need +[]-+[]-+[]-+[]-


 Any way, it's odd how I did it right with the solar cells but not the batteries...

I digress, I do have 4 NiCads... are those less picky about charge? From what I had read most people seemed to do ok with just getting an approximate charging voltage and off they went, doesn't make it right, but I figured after seeing it enough that maybe they knew what they were doing.

I am thinking about scrapping most of this and stealing someone else's idea of getting a kit to charge a small lithium pack and using a 5v step up. Failure isn't fun, but you can't just ignore it.

Getting something that works is a sound idea. Failure is fun when things explode...


 Sadly the batteries didn't even explode, oh well maybe I can salvage them in my store bought charger and reuse the cells for the next project. I still don't understand what didn't work with the circuit I made (not the one that I drew)... well I guess it could have been the nimhs are picky with their charging? I dunno.

 Hah, true, that was just me being an idiot, sorry, no the batteries are in a pack, so they are +-+-+-+- on both sides, sorry. brain fart. I expended much more thought on finding an app to draw it all for me than I did drawing it I guess.

My bad.

 PS I meant to say the solar panels were stolen from some lawn lamps...