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 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.

 

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

 

hey you still here?. Let me know if you need any help. InCan help

Take a 5 volt regulator and decrease the voltage to 3.7v with resistors and transistor(s).

 

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!

 

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. Just put ur 12volt in the input where it says 5 volt. This regulator can go Up to 24 volts.Good luck!

 

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!

Don’t use transformer’s it cost you a lot of energy and loses.

 

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?

 

sure it can but take a lot of time

 

@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!

 

It’s just great and it will charge ur battery fully!

It can also over-charge it. The only 'great' thing about it will be the sound of the cell explosion !

 

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.

 

Try a MAX745 module?
https://www.aliexpress.com/item/32849709002.html

 

take some lessons from the internet or some school?

Your misinformation shows that you need the the lessons, not us.
Please do not give electronic advice here when you obviously know just enough to be dangerous.

 

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.

 

use a 5v reg to step it down from 12v, then connect the output to a usb powered 3.7v charger. This will allow safe charging and prevention of overcharging of the cell. Hopfully the charger is a type that has a load output to prevent over discharge of the cell.

 

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?

THAT ADVICE, to "throw away all the transformers" is the worst advice I have heard in several years!!
Certainly there are in many cases other, possibly more efficient, ways to do things.
There are also a lot of situations where an adequate transformer is very much the best choice. Just not everywhere.!!!!!!

To charge the 3.7 volt batteries you can use a step-down switching regulator and a battery charging control circuit. THAT will be the efficient scheme.

 

Don’t use transformer’s it cost you a lot of energy and loses.

Nonsense. A linear regulator stepping down from the MPP point of a 12V panel (about 15V) to 3.7V is never going to be more than 25% efficient, no matter how much you fiddle with its feedback resistances.
A decent MPPT controller will manage over 90%.
There are small MPPT control IC in Texas Instruments’ Benchmarq range, which will do the job. What you need is a buck regulator that regulates its input voltage to match the MPPT voltage of the panel.
You also need to makes sure that it cannot overcharge a lithium battery, as it will explode.