12V solar panel to 3.7V li battery charger

Thread Starter

cable1cutter

Joined Jan 21, 2023
7
I have a solar pane that gives about 12 volt and 120 mah and I want to make a 3.7 v battery charger. I dont have a voltage regulator I just have transformers, resistors and capacitors ect. and I dont have a much knowledge about electronics. Please can you send a circuit? Thanks.
 
I have a solar pane that gives about 12 volt and 120 mah and I want to make a 3.7 v battery charger. I dont have a voltage regulator I just have transformers, resistors and capacitors ect. and I dont have a much knowledge about electronics. Please can you send a circuit? Thanks.
hey you still here?. Let me know if you need any help. InCan help
 
I have a solar pane that gives about 12 volt and 120 mah and I want to make a 3.7 v battery charger. I dont have a voltage regulator I just have transformers, resistors and capacitors ect. and I dont have a much knowledge about electronics. Please can you send a circuit? Thanks.
just play with R1 and R2 till you get 3.7 V and ur done. Use 1 watt resistors so you can get ur current smoothly without any strain on your other components. Good luck!
 

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I would use a LM317 regulator or a readymade LM2596, if it's a lithium battery it needs a dedicated charger as they can explode if
just play with R1 and R2 till you get 3.7 V and ur done. Use 1 watt resistors so you can get ur current smoothly without any strain on your other components. Good luck!
Man! Stay in the future not in the past. I should say’ throw all transformers in ur garbage and go deal with real electronic. Hint:’ take some lessons from the internet or some school?
 
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Alec_t

Joined Sep 17, 2013
14,280
@ElectronDesign
Do you understand the dangers of mis-charging lithium batteries? Your circuit has no way to prevent damage from trying to charge an over-discharged cell, nor does it have any way of correctly limiting charging current. Also, the cell is not fully charged if its terminal voltage is 3.7V.
 
I have a solar pane that gives about 12 volt and 120 mah and I want to make a 3.7 v battery charger. I dont have a voltage regulator I just have transformers, resistors and capacitors ect. and I dont have a much knowledge about electronics. Please can you send a circuit? Thanks.
This is better! connect ur 12 volt panel to the 5 volt regulator and you can charge ur 3.7 volt battery.to charge You need some more volts and that’s great for the 3.7 volts. It’s simple just think or take some lessons somewhere good luck!
 
@ElectronDesign
Do you understand the dangers of mis-charging lithium batteries? Your circuit has no way to prevent damage from trying to charge an over-discharged cell, nor does it have any way of correctly limiting charging current. Also, the cell is not fully charged if its terminal voltage is 3.7V.
That why is a 5 volt regulator the best solution to load a battery 3.7 volts! It’s just great and it will charge ur battery fully! Try and learn more from electronic everyday! Good luck!
 

BobTPH

Joined Jun 5, 2013
8,807
That why is a 5 volt regulator the best solution to load a battery 3.7 volts! It’s just great and it will charge ur battery fully! Try and learn more from electronic everyday! Good luck!
It is a great fire starter, not so great as a battery charger.

To the TS, you are not capable of doing this safely. Find a commercial solution or give up this idea.

To @Electron Design: Your advice is not sound, you should not be giving answers when you know so little about it. Apple and Samsung have had disasters with their Li Ion battery chargers, and you are not as qualified as their engineers.
 

Thread Starter

cable1cutter

Joined Jan 21, 2023
7
Okay, I just brought LM2596 and tp4056 online. When it arrives I wil connect solar panel to regulator then charger module. For being sure, is it OK for charging a 1200 mah 18650 li ion battery?

I would use a LM317 regulator or a readymade LM2596, if it's a lithium battery it needs a dedicated charger as they can explode if not charged correctly.
 
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