[scarenoob]

After years of buying and then modifying solar lights, I finally found a way to build my own mini solar battery chargers to power LED lights, motors, etc.

From

To

^ Not all of them have the same outputs: 3.7V, 5V, 9V, 12V.

Parts:

• TP4056 lithium Ion battery charging modules
• 1N5408 Diodes
• 18650 or 14500 (AA Size) 3.7V Lithium Ion Protected Batteries
• 18650 Batteries (1800mAh and 2600mAh)
• 18560 or 14500 Battery Holders With Wires
• Step-Up Voltage Regulators (9V/12V - U3V70x family)
• Red/Black 24AWG? Stranded Wires
• Soldering iron + Solder
• 2 Pin Waterproof Connectors
• 12V Waterproof Toggle Rocker Switches (they also works on 3.7V, 9V)
• Waterproof Enclosure Boxes 100x68x50mm
• Solar Panels: 5.5V 1.6W 290mA, 6V 3.5W 583mA

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I got the idea from this guy:

Details about TP4056:

The TP4056: Lithium Ion/polymer Battery Charger IC

Learn how to use the TP4056 properly. There's a right way, and a wrong way, to use it to safely charge Lithium Ion batteries.

www.best-microcontroller-projects.com

Tp4056a Li Ion Battery Chargingdischarging Module| Components101

components101.com

TP4056:
The one bad thing about the module is that it doesn't have a automatic switch controlling the OUTPUT.
Options:
1) A simple hack as shown in the video above.
2) Add a switch like BJT Transistor or MOSFET.

I have tried using BJT Transistor but unfortunately it suck down volts (voltage drops from 3.7V to @ 2.4V).

18650 Battery - Rechargeable Li-Ion Cells - Battery Junction

Shop rechargeable lithium-ion 18650 batteries. Genuine cells for unbelievable low prices – search our wide selection by brand, capacity, discharge and more.

www.batteryjunction.com

14500 Batteries [AA Lithium] | Battery Junction

Save money and go rechargeable! 14500 batteries are lithium AAs designed to fit most household electronics. The cell size you need at a price you'll love, browse 14500 batteries at Battery Junction.

www.batteryjunction.com

Pololu - Step-Up Voltage Regulators

Boost converters generate a regulated output voltage that is higher than the input voltage.

www.pololu.com

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Unfortunately I didn't take some pictures in the beginning.

 

[scarenoob]

 

[scarenoob]

 

[scarenoob]

 

[Jaybo]

How long does it take to charge the battery?

Sent from my Pixel 3a XL using Tapatalk

 

[scarenoob]

How long does it take to charge the battery?

Sent from my Pixel 3a XL using Tapatalk

Maximum charge current is 1A but I wouldn't go over 800mAh based on some comments I have read.

Batteries	Solar Panels	Hours (FULL SUN)	Hours (-10%)	Hours (-40%)
1000mAh
	5.5V 1.6W 290mA	3.4	3.8	4.8
	6V 3.5W 583mA	1.7	1.9	2.4
1800mAh
	5.5V 1.6W 290mA	6.2	6.8	8.7
	6V 3.5W 583mA	3.1	3.4	4.3
2600mAh
	5.5V 1.6W 290mA	9	9.9	13
	6V 3.5W 583mA	4.5	4.9	6.2

 

[annamarykahn]

an excellent source of free/used 18650 are from laptop batteries ... some 18650 cells from laptop batteries will be dead ... if you have an electrical meter check their voltages ... hopefully some will measure ok and can be refurbished, but that'll entail purchasing specific battery charges with this & other features ... but then if you have one, why bother solar charging ;-)

amk

 

[scarenoob]

an excellent source of free/used 18650 are from laptop batteries ... some 18650 cells from laptop batteries will be dead ... if you have an electrical meter check their voltages ... hopefully some will measure ok and can be refurbished, but that'll entail purchasing specific battery charges with this & other features ... but then if you have one, why bother solar charging ;-)

amk

I have thought about it but we never kept them. When the laptop start to stop working properly, we trade it in for new one (discounted price).

Sent from my XT1650 using Tapatalk

 

[scarenoob]

Updates:

#1 - Solar chargers I have put together (using the hack as shown in the video above) didn't work as I expected. They worked fine when I tested them in the garage but when left outside, they didn't switch ON at night. After investigating the switching problem, I have discovered that solar panels were still charging (anywhere 0.2V to 2V) even at night.

#2 -
So I had to start over again and decided to give the MOSFET a chance again. After searching on Google, I found someone tried to build a similar solar charger setup. Based on that person setup, I found out what is the MOSFET I should be using. I ordered 3x NDP6020P (P Channel) MOSFETs from digikey.

https://electronics.stackexchange.com/questions/442898/p-or-n-channel-mosfet-to-disconnect-a-load

MOSFET - NDP6020P ON Semiconductor | Discrete Semiconductor Products | DigiKey

Today, they arrived. I took apart (removed the hack) one of the solar chargers and put in the MOSFET. Now the solar charger seem to be working as should. The only issue I have now is the switching is not instant (OFF/ON). Not 100% perfect but it works.

Since I currently have 3 MOSFETs, I have fixed 3 out of 7 solar chargers. Will have to order more to fix the rest.

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Oct 28, 2020

Here's the final (hopefully!) modification: