solar light (with USB charger) not working

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carolmiers
 
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solar light (with USB charger) not working

Post by carolmiers »

Hello, This is not strictly an Adafruit product but I have begun to read about the USB solar charger to find out if the design of a faulty solar light (and usb charger) I have has the same modular parts, uses similar electronics so I can understand why it is not working. So I wonder if someone please can help me?
It is less than a year old and should be in warranty but in fact the manufacturers were kind enough to send one from the US to France, where I am, when usually they are ordered in batches. Also I thought it would be good to learn about it while trying to fix it.
So the problem is that after the solar panel is in sunlight for some hours, and the LED switch is pressed, the LED light comes on for a few minutes then goes off as if some thing has reset it. It won't go back on again, as far as I can tell without the panel being outside again.
When I measure the battery voltage it is 3V, when I press the switch it short circuits, so appears to work, the LED is clearly not broken. There is a surface mount pcb with a U1 being 8-pin like a 555 timer chip. There is in an L2 position something called 3R3 possibly an inductor. There is a '47' I guess a transistor. But is there something that often goes wrong with these devices that someone could direct me towards please? I do have an Adafruit kit I bought some time ago, MintyBoost v3.0 so I wish I had kept following the blog back then but better late than ever. Thank you to all replies. Carol

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adafruit_support_bill
 
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Re: solar light (with USB charger) not working

Post by adafruit_support_bill »

Hard to say without knowing much about the circuit. If it is a LiPo or LIon battery, 3v is below the minimum safe charge level. It may simply be a case of the battery not holding a charge and the protection circuit is shutting it down.

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wdickenson
 
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Re: solar light (with USB charger) not working

Post by wdickenson »

This is a total guess but since I built a trinket powered solar light, these symptoms sound vaguely familiar. But again, this is a true shot in the dark. I don't have anything to do with the unit you describe since all of mine are now in my yard !

My original version looped until the light sensor (CDS) indicated it was dark. Then it waited 20 more minutes and turned on the Neopixel. The light stayed on until A) 4 hours elapsed, B) no battery power. I also had a switch to trigger the light manually. But the issue was that when you did that and it entered "night" state, in an amazing lack of thought, it ignored the switch until the CDS detected dawn. After it detected dawn, it stayed off for 5 hours. Which rather sounds like what you describe. Take a flashlight and light up your sensor ( assuming it doesn't use the solar panel light my first model did). Then press the switch and see if you get another few minutes. If you do, probably the issue but i have no idea how to fix ( mine involved some better programming).

Or, since you did this test in daylight, put a piece of tape over the sensor and repeat. See if it goes past the short period.

Again, this is purely a guess but even if true, no idea if you can fix what you have (and for what it's worth, the Adafruit charger does work very nicely on this )

Thanks

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carolmiers
 
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Re: solar light (with USB charger) not working

Post by carolmiers »

Hello, That's a very interesting idea. I can't see a light-detecting sensor ! The light switch has three positions (on, on-bright, off) I think it only charges the battery when the switch is off - I guess otherwise the light should be on, even if it is daylight. I have not yet solved it, but will post again when I find out something else. Many thanks, really appreciated. P.s.
It is an 11.1 Wh lithium polymer battery

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carolmiers
 
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Re: solar light (with USB charger) not working

Post by carolmiers »

I found out that it is a Lion battery and the circuit is in shutdown at 3V, it has be to as you said, at 3.7V to operate. So the charging circuit may be faulty or the battery no longer holding charge as you suggested (although it is less than a year old) or the sunlight is very weak (which seems unlikely). This version has nothing to indicate whether the light is switched on or off (when it is faulty ie not working) so leaving it in the sun does not always make a difference.

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adafruit_support_bill
 
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Re: solar light (with USB charger) not working

Post by adafruit_support_bill »

You could try replacing the battery. Some are easily replaced. Other have the battery soldered into the circuit.

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MarioJog
 
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Re: solar light (with USB charger) not working

Post by MarioJog »

Hi, I wanted to get the charger (solar charger v4) for a home automation product I have in mind, but I would like to ask you if I can do a simple modification to avoid using the big capacitor:
1. Could I replace the capacitor for a second branch of the battery? that way, if a sudden drop happens, the battery will backup. Would that spoil the proper charging process?
2. Instead of the capacitor, could I use a single coin cell battery in series with a schottky diode as to protect having incoming current?
The tutorial is great, congrats, I only miss screen shots of the v4 version. Could you upload a capture of the v4 schematic for better understanding?

Thanks and god job!

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adafruit_support_bill
 
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Re: solar light (with USB charger) not working

Post by adafruit_support_bill »

1) That wouldn't work. The capacitor is in parallel with the panel and the panel voltage is too high for a LiPo.

2) Maybe with a lead-acid battery. But that would be bulkier than the capacitor.
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Solar Charger.png
Solar Charger.png (27.49 KiB) Viewed 487 times

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MarioJog
 
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Re: solar light (with USB charger) not working

Post by MarioJog »

All rite, thanks for the very quick response. I'll keep exploring more possibilities on replacing such big capacitor, maybe limiting the voltage from the panel and using a smaller cap... it's kind of big for what I was thinking to put the charger into.
Thanks again

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