Garden lights working on 18650 lithium single cell...

[Externet]

The common variety of solar garden lights use a dedicated four pin IC to manage operation.

Is there a similar single IC for garden lights that use a lithium cell ? Or modifying one to handle a 5V panel and a lithium cell ?

Edited. Sorry, goofed by not searching first...
The complex and the simple ways :

 

[Externet]

Something wrong, one did not attach? Images borrowed from the web.

 

[Audioguru]

A solar garden light feeds about 10mA into a 3V LED for 8 hours. A 2V solar panel and 1.2V/300mAh AAA rechargeable cell is usually used with an IC that boosts the 1.2V battery voltage to 3V.
An 18650 cell averages 3.7V and has a capacity of about 3000mAh so it would power the solar garden light for 8 nights brightly before needing a recharge, or it will power 8 LEDs brightly each night.

I have one solar garden light that has a 3.5V solar panel and has a 3.3V/400mAh Li-Fe-O4 cell the size of an AAA cell. It charges all day and lights one white LED brightly all night. It uses a standard 5252F IC that is used in normal solar garden lights that use an inductor to boost the 1.2V battery voltage but doesn't need an inductor to boost the voltage, instead it has a current-limiting resistor in series with the LED. I guess the IC simply turns the LED on when it is dark.

 

[Audioguru]

Where will you find LEDs that have matched forward voltages? From a Chinese flashlight?

For the transistor to saturate its base current must be 1/10th the collector current. The 47k resistor limits the base current to only about 0.1mA so the collector current will be 1mA and each LED very dimly glows with only 1/8th of a mA.

The lithium cell must never be charged higher than 4.20V but your circuit will cause it to explode when it is charging to about 4.8V.

 

[Externet]

Thanks. Yes, that second circuit seems wrong. The paralleled LEDs is obviously goofy.

Checked the 5252F data sheet and does not show useable with lithium cells... For a 5.0V weak panel perhaps after a diode...
Such chip is to boost 1.2V to the LED Vf. A chip fed by 3.x to 4.2V from single lithium cell would not be needed.

Still after a circuit or IC that will safely charge to 4.1 - 4.2V at daylight and turn a non-LED device on when dark.

 

[Audioguru]

My solar garden light with the 3.3V Li-Fe-04 battery cell and a 5252F IC is marked inside to use a 1.2V AAA cell and its pcb has the voltage boosting inductor not installed. The 10440 battery cell is sold at Walmart but at the normal Li-Ion 3.7V.

Hee, hee. The Chinese company who makes (or buys) the Li-Fe-04 battery cell also makes kids shoes with LEDs in them. They also make fabric for parachutes.

 

[Externet]

Thanks, Audioguru. I will then investigate further to find an application note for the 5252F as you mentioned, without the inductor. Or will have to buy one and check how is it wired.
Seems like without the inductor, that IC will only work as light sensing and turning the load on at dark, the boosting section inoperative. Which is OK.

Found this cheap board/kit with no schematic... seems meant to light a LED, not another kind of load as am after. Perhaps jumpering the load series resistor would apply power to the load with no current limitation.

----> https://www.aliexpress.com/item/DIY...id=7c14da39-98be-4852-a906-08244f6e3559&tpp=1

Made the schematic observing the board...

Now, is there any chinese that can be believed ? Uses the S8050 transistor :
Now watch this : Both PNP and NPN

PNP ----> http://www.datasheet.hk/view_download.php?id=1025659&file=0001\s8050_4577.pdf

NPN ----> https://www.digchip.com/datasheets/parts/datasheet/284/S8050-pdf.php

 

[Audioguru]

Chinese people do not know our letter "P" then PNP is the same as NPN.
A Chinese grocery store opened in my city. Their meat department had Lamp Chops because they see that our "b" looks the same as our "p". Their BBQ chickens looked like pigeons.

 

[BobK]

Their BBQ chickens looked like pigeons.

When visiting Shanghai, I noted to my wife that it was unusual in a big city not to see pigeons everywhere. Then we went out for dinner and looked at the menu...

Bob