Solar panel charger with auto shutoff. Solar LED drivers.

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Magnets
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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby Magnets » Sun Mar 13, 2016 5:56 pm

How do the QX5252 operate with multiple AA batteries?

You just need to make sure the solar voltage is above battery for it to charge? I assume it still tries to run down to 0.9v before cutting out? Do you need to manually set the solar voltage to effectively be your termination voltage?

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burger2227
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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby burger2227 » Sun Mar 13, 2016 6:16 pm

With more batteries up to 5 volts you can power more LED's. I've run up to 9 fairly well. Bright LED's need 3 volts normally so 3 in series may work with 5 volts OK. Each parallel circuit cuts coil current in half.

Pin 1 reads the solar voltage down to .3 volts and thus turns the LED on when dark.

The chip shuts down the LED when battery voltage on Pin 2 goes below .9 volts to protect the battery. Some solar days are not very good for charging so a dead battery would soon result.

A light sensor resistor or diode can supply battery voltage to pin 1 without the solar cell and it will also turn on the LED(s) when dark.

Rechargeable batteries are a must when using a solar or an outside DC power source on pin 1. Cannot use AC!

Manual switching should be done on the negative battery to the pin 3 of chip and LED common.
Flashlights often are set up that way so connect the chip ground above the switch or it will drain it.
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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby Magnets » Mon Mar 14, 2016 1:51 pm

Interesting, thanks.

I recall reading somewhere that the QX5252 terminates charge when the cell reaches 1.4v but in my case that isn't happening. I modified a store bought light with a 47uH inductor, 5v 1.3w panel and a mini DC buck set to output 2v and 1xAAA nimh. In full sun it charges the battery at 180ma but it seems to keep going over 1.50v which will eventually damage the cell at these rates.

With the battery disconnected it read 1.50v, in circuit it was around 1.54v IIRC and still taking 150ma

The board has a chip-on-board blob which I assume is a qx5252, but I guess it may be something different.

I see V(batt) is 1.50v, so does it terminate at 1.50v? :?:


edit: I see the solar cell is connected through a diode to the battery so will always be pulled to the solar voltage? i.e. you can't fast charge the cell?

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby burger2227 » Mon Mar 14, 2016 4:59 pm

The QX5252 chip has a diode built into pin 1 to pin 2. Battery + goes to pin 2 so it is not the same chip.

A rechargeable AA battery is 1.25 volts max, so cut down the voltage to get current down. If you want a trickle charge use a resistor to set it lower like 20 ma.

The first circuit in this topic uses a voltage regulator that turns off when a transistor shuts it off to stop charging
at a certain voltage. The circuit is no necessary for solar panels normally as the charging current is much lower.
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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby Rickster » Mon Aug 08, 2016 10:38 am

>>the two biggest problems were the AC prongs. which were really hard to solder to. I ended up wrapping solid wire around the prongs on the top and bottom of the board and soldering the circuit to that. The prongs moved.

When soldering things line AC plug prongs - that have to keep alignment, and tend to melt in their plastic - I find that if I plug them into a receptical (like an unpowered extension cord or power strip, obviously) during soldering, they will maintain their alignment perfectly.

This also works with things like berg post headers (plug into berg post sockets) and other similar.

~ Rick

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby Rickster » Mon Aug 08, 2016 10:41 am

5252F

Does anyone know the minimum operating voltage?

Given the claimed "flicker free" shutdown, I figure there must be built in hysteresis.

Has anyone tested the actual "on voltage", "off", and "back on"?

~ Rick

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby burger2227 » Mon Aug 08, 2016 1:28 pm

Minimum is one 1.25 volt rechargeable battery.

At .9 volts the chip turns off to save the battery.

I have seen some circuits flicker with button batteries.
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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby Rickster » Mon Aug 08, 2016 2:44 pm

Thanks.

After it shuts off at 0.9V, how much does the battery need to charge to before the chip will power back up and light the LEDs?

I can't find it in the specs, but I suspect the "on" voltage is a bit higher (say 1.0V) than the 0.9V "off/shutdown" voltage.

I.e. I'm figuring the "ain't-flicker" feature is implemented by some hysteresis, whereby once it shuts down at 0.9V, the battery has to get back to (say) 1.0V before it will come on again.

Without some amount of hysteresis, the LED would flicker when the battery was discharged.
At ("exactly") 0.9V, it would power off. The battery, no longer having any load, would "rebound" slightly - to, say 0.91V - and the LED would come on (briefly.
The battery would then be loaded, quickly go back to below 0.9V, chip shutdown, battery rebound... Repeat. Flickering each time.

Of course each time the battery would drain slightly more.
The battery would rebound to a lower voltage, so the flicker would be shorter.
Until... The rebound was to 0.9V... And then we wouldn't come on any more...

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby burger2227 » Wed Aug 17, 2016 7:26 am

Yes the chip uses hysteresis to a point, but a battery voltage may climb up after being shut off for a while on its own.

Circuits without the chip may flicker more as transistors may trigger with .6 volts, the drop across diodes.
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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby Rickster » Wed Aug 17, 2016 9:54 am

After testing, I determined that it does not use simple hysteresis to prevent flickering - which may prevent me from using it for what I had hoped.

Once it shuts down because voltage goes below ~1.0V, the solar cells must be exposed to light to reset the low battery condition - if the battery has been charged by some other means.

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby Rickster » Wed Aug 17, 2016 1:07 pm

I found a way to utilize the 5252 in some very useful ways.

Utilizing a Schottky diode, and capacitor, you can use the device as a significant voltage booster.
I was able to get 7V out of a single AA cell..

Combine this with a low quiescent current, low dropout regulator (like MCP1702-5V) and you can power some interesting projects at 5V with a single AA.

You could, of course use a solar cell and make your device solar powered...
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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby sadesh » Wed May 24, 2017 8:23 am

That was great invention of solar LED. :D congrats,

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby mia10 » Fri Jul 14, 2017 1:40 am

sadesh wrote:That was great invention of solar LED. :D congrats,


hello
Is it possible to operate solar LED drivers with auto shutoff because once I tried it but does not get success??

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby burger2227 » Fri Jul 14, 2017 11:00 am

Show us your circuit. Create drawing with Paint and send it to PhotoBucket or PostImage. Copy Direct link into Img brackets in post editor here.

Or tell us what you have attached to each pin of 5252 chip.
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Re: Solar panel charger with auto shutoff. Solar LED drivers

Postby teren » Wed Jul 26, 2017 1:05 am

holtt wrote:Hi, glad I found this thread! I've been messing with the QX5252 the last week, making a nice little minimal Joule Thief-like setup.

But I've run into one quandary, and wondered if any of you knew a way around it.

As mentioned before, the chip will turn off the light when the voltage gets below 0.9 or so, to prevent over-discharge of a rechargeable battery.

But in my specific application, I'd like it to just keep going - to NOT shut down, but instead just drain the battery to nothing. I'm not using rechargeables, but rather old "dead" AAs.

Any thoughts on how to bypass or disable this feature? I actually want it to drain an old AA down to as low as it goes, and I don't care if it gets kind of dim after a while.

----

Here's the back story about what/why I'm doing if you're curious...

I'm looking at building some small lights for recycling stations at a festival that goes on for around a week. I need about 100 of them, and it's got to be cheap, easy to make, and low maintenance.

My thought was to use a Joule Thief circuit, and use "dead" AA batteries to run it all - which would really be in the spirit of recycling and all that. I could load them up with "dead" AAs (i can get hundreds at work), then just keep an eye on them during the festival and swap out the ones that finally go out. I'm used to toroid-style Joule Thief circuits running for a week just fine, so I know this doesn't have to happen often.

The problem is, when I use "dead" AA batteries with the QX5252, I only get about a day's worth of light out of them with this chip. Specifically because the low V cutoff kicks in and turns it off. A standard (toroid coil style) Joule Thief light will just keep draining, and go for days and give me plenty of light. These only last a short time, specifically without using a solar cell, and a 330 uH inductor

I could just make the standard coil type, but since I need around 100 of them., that's a lot of toroid coils to wind. So when I found the QX5252 (and bought 100 of them), I thought I had my answer. Very easy to make with out much fuss. And dirt cheap as well.


Hello,

Has anyone purchased a cheap solar panel online??
I bought a solar panel but it looks like a bad in quality and cost is so high that is why in need to buy a solar panel at an affordable price.
Thanks for any appreciation.

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Re: Solar panel charger with auto shutoff. Solar LED drivers.

Postby burger2227 » Wed Jul 26, 2017 9:52 am

No way to alter what the 5252 chip does, but you a make you own jewel thief circuits. Most transistors will cut off at .6 volts anyhow.

You can get cheap small solar panels with the circuit boards already made from solar walk lights that can cost only a dollar.
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