Any Electrical Engineers in here? Solar light help

So I found a schematic online to build my own solar light, that charges during the day and lights at night. I wired it all up and it seems to work with the exception of the battery not charging during the day.

I am a complete newb to an electronic/circuit stuff, Im hoping to teach myself with this as I go. The most Ive done before is wire up LEDs from a powersupply using the correct resistors, so I apologize for any newbie'ness to this thread.

I'm a little confused as to how this thing works because it has 3 potentiometers on it? I dont the potentiometers closest to the LEDs controls the brightness of the LEDs. But I have no idea what the other 2 do, and think this may be part of my charging problem. (Ive never wired or used a potentiometer before so I dont know if I even wired them correctly, but I think so.)

Can someone take a look at the schematic and my project and help me out at all? Thanks!

The solar cells put out 5.5v @ 15ma each.

Schematic:


My project (wired exactly as the schematic)


Here is a labeled version so when you explain things you can idiot proof my understanding. lol

It looks like the potentiometer to the far left on the schematic (the one closest to the photovoltaic cell) controls the threshold at which the circuit decided that it's dark enough outside to turn on the LEDs.

The pot at the top of the schematic looks like it controls the threshold at which the battery is cut off from the LEDs to prevent it from being drained too deeply. And the pot on the far right is LED brightness, of course.

Re: Any Electrical Engineers in here? Solar light

[ QUOTE ]
PhotonWrangler said:
It looks like the potentiometer to the far left on the schematic (the one closest to the photovoltaic cell) controls the threshold at which the circuit decided that it's dark enough outside to turn on the LEDs.

The pot at the top of the schematic looks like it controls the threshold at which the battery is cut off from the LEDs to prevent it from being drained too deeply. And the pot on the far right is LED brightness, of course.

[/ QUOTE ]

I agree. Are the LEDs turning off during the day? If not, maybe that's why the battery isn't charging. Or maybe the battery doesn't hold a charge anymore because it was too deeply discharged.

Re: Any Electrical Engineers in here? Solar light

Hmm, the lights do turn off when I move them towards a light source. The battery was brand new so it did sit overnight (lights on) before they received a full charge, would that kill a NiMH battery?

Re: Any Electrical Engineers in here? Solar light

I'm not an expert on NiMh but I do believe that they should be fully charged before pressing them into service.

Re: Any Electrical Engineers in here? Solar light

If the lights turn off when you move it toward a light, that means that the lights must be on when you move it away from the light so the battery's not completely dead. What makes you think it's not charging the battery? Can you measure the voltage across the battery? Was it fully charged before hand?

Re: Any Electrical Engineers in here? Solar light

one thing i noticed, and if you have a meter you could check it.
your trying to charge a 9V cell, with a 10V solar pannel thing. PLUS you got a diode in there doing a voltage drop.
(i am dealing with the same problem myself this week :-(

so first to get solar POWER, you gotta have FULL sun, clouds are like 1/6th the output.
and
to CHARGE the battery you need a reasonable voltage differential potential. umm, that means a higher voltage on the wimpy pannels, than the wimpy battery
SO
if you could test things, any things it would give you a VISION of why its not charging.

TEST: (one or all of the following, depending on what you CAN test)

the output voltage of the solar cell, using a simple voltmeter.

The voltage of the battery you expect to charge

and most importantly, the Miliamps (the flow) from the solar cell. to do that, you would disconnect the solar cell from the battery somewheres, and put a miliamp meter in between it.

actually the solar cells output is so LOW that you could potentially do some of the voltage tests with LEDS running off the solar cell, if you did not have a meter.

that is all i know, i dont understand the cuircut stuff, as that is beyond my present skills.

BTW , great pics, and labeling and all, cute cool project, wish you well.

Re: Any Electrical Engineers in here? Solar light

I fully charged my batts in solar lights I had before sending them into service -- just used my batt charger...

Re: Any Electrical Engineers in here? Solar light

Well apparently my solar cells will produce 5.5V each if they are physically touching the sun, otherwise their output drops dramatically based on the distance to the source.

Does anyone have a good source for solar cells? I bought my at Solarbotic. ??

Re: Any Electrical Engineers in here? Solar light

for doing what your doing those are ok, how many MA total is your battery?
can you aquire full sun for it ?
did you find out your charge MA rate?
they have all kindsa stuff at e-bay, even HUGE ones, way to big for that kinda battery.
radioshack even sells the ones like you have there, if you just wanted to up it a BIT. mabey not cheap.

Re: Any Electrical Engineers in here? Solar light

[ QUOTE ]
for doing what your doing those are ok, how many MA total is your battery?
can you aquire full sun for it ?
did you find out your charge MA rate?


[/ QUOTE ]

Yeah each one charges at 15ma, so it charges pretty slow. I think if I wanted to continue to use this setup I would need 1 more solar cell because when I put the multimeter to it, even in direct sun it's not getting to the 5.5v (ea) it promised. I have to have my shoplight RIGHT ontop if it to get to that level.


Anyone see anything wrong with this little circuit I drew up?
Basically I just want a simple solar light, turns on at night, charges during the day, efficient as possible.

Sorry if I have things drawn wrong, backwards I used MS Paint /ubbthreads/images/graemlins/grin.gif and I'm learning as I go...