TP4056 18650 Charging Board... Series Out?

onesojourner: I am using 3 boards and 3 batteries.

still connecting the OUT in series won't work coz the chip is designed to turn the charging off when battery reaches 4.2V.

So are you saying the chip would see the 12.6v?

I guess this brings up some more questions.

Can the input to these boards all use the same 5v source provided it there are enough amps?

Can I run all three outputs in parallel and then step up the 4.2v to 12v?

Here is a quick sketch I did a while back. I am trying to build a simple solar powered 18650 powered light. I have a few P channel mosfets laying around. They are not logic level. I believe they need 9v at the gate to shut off.

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onesojourner: I am using 3 boards and 3 batteries.

If you look at the board pictured in the original post, you can see the trace connecting the input "-" to the output "OUT-". If you wire the outputs in series with a common ground at "-" two of the "OUT+" pins will be shorted to ground. The charger may tolerate this, since they current limit by design, but shorting batteries that have any charge on them is not going to end well.

onesojourner: So are you saying the chip would see the 12.6v?

Yes, and it won't charge. It may even fry that chip. (haven't checked the ratings)

Can the input to these boards all use the same 5v source provided it there are enough amps?

Absolutely. Even if there aren't enough amps it will work by charging at a lower current.

Can I run all three outputs in parallel and then step up the 4.2v to 12v?

It should work. Although that 4.2v will soon drop back to 3.7v.

I am trying to build a simple solar powered 18650 powered light.

maybe you should tell more about your pproject and we can help you find the best solution. :)

There are better options, You could use a 19 or 18v laptop battery pack. It has a built in balancing circuit. You just have to step down the voltage to 12V.

Or

you could use a DIY powerbank kit like this which could charge multiple 18650 cells without any problems.

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I am mostly just trying to educate myself.

I am trying to build 18650 solar light. I would like the lights to come on when it gets dark and go off when the batteries reach a set voltage or when it gets light out.

LED = 12V * 50mA = 0.6W

I have 3 solar panels to choose from: Solar Panel 2.5W 5V/500mAh (x2)

Solar Panel 12V 3W

I have some p-channel mosfets (9v gate) and I have some logic level P channels on the way.

I have a few cheap 18650s, and I hope to have some Panasonic 3400s fairly soon.

onesojourner: I am trying to build 18650 solar light. I would like the lights to come on when it gets dark and go off when the batteries reach a set voltage or when it gets light out.

You can use a small photoresistor to get the lights to turn on when it gets dark and turn off when it's not.

The TP4056 module has a discharge cutoff function that stops the battery from providing power when it's charge is too low to prevent any damage to the battery.

LED = 12V * 50mA = 0.6W

I have a few cheap 18650s, and I hope to have some Panasonic 3400s fairly soon.

Well, why didn't you say this before. You don't really need 3 batteries for that. A single 2600mAH 18650 has about 9.3WH so it can power you 0.6W LED for about 13-15 hours = more than enough to power your light from for a dusk to dawn. Them Panasonic 3400s will give you well above a 20 hour runtime.

You just have to boost your battery voltage to attain 12V

I have 3 solar panels to choose from: Solar Panel 2.5W 5V/500mAh (x2)

Solar Panel 12V 3W

Just use 1x 5V (2.5W) solar panel for the setup I suggested. 500mA is more than enough to charge a single 18650 cell. At optimum conditions your panel will fully charge a 2600mAH cell within 6 hours.

I have some p-channel mosfets (9v gate) and I have some logic level P channels on the way

You don't really need MOSFETs for a 0.6W LED, Transistors will do the job. Just connect that photoresistor to the Transistor.

Watch this example --> https://www.youtube.com/watch?v=eEBMTpxdPiE

Noobian: ... The TP4056 module has a discharge cutoff function that stops the battery from providing power when it's charge is too low to prevent any damage to the battery. ...

Maybe I've missed something, but I don't think this is correct. The TP4056 is a charge only device.

Noobian: The TP4056 module has a discharge cutoff function that stops the battery from providing power when it's charge is too low to prevent any damage to the battery.

Dont beleive you.

The output of the TP4056 module connects direct to the battery and the load is connected across the same connections as well.

As the load does not go through the TP4056 module even if the TP4056 module were to shut down, the battery is still connected to the load.

MrMark: Maybe I've missed something, but I don't think this is correct. The TP4056 is a charge only device.

Actually you did miss something ;), did you not see the DW01A IC and the FS8205A dual MOSFET in OPs picture? The second version of TP4056 modules comes with these protection chips.

Julian Ilett has done a good review on these modules.

srnet: Dont beleive you.

The output of the TP4056 module connects direct to the battery and the load is connected across the same connections as well.

As the load does not go through the TP4056 module even if the TP4056 module were to shut down, the battery is still connected to the load.

Wrong, you're talking about these first version of the TP4056 modules, OP has posted the second version with battery protection features. Please read the Original post before replying to any of the later posts. :P

Circuit for the second version. |500x283

Noobian: Wrong, you're talking about these first version of the TP4056 modules, OP has posted the second version with battery protection features. Please read the Original post before replying to any of the later posts. :P

Fair point, although the original post has now been edited.

However, a cut of voltage of 2.5V is way too low. Not a good idea to let the batteries discharge that low on a regular basis.

srnet: Fair point, although the original post has now been edited.

However, a cut of voltage of 2.5V is way too low. Not a good idea to let the batteries discharge that low on a regular basis.

That depends on the battery. Usual 18650s has a discharge cut-off voltage at 2.75 volts but since the OP said he might use them Panasonic 3400s, which has a discharge cut-off at 2.5v.

Anyways these cheap modules are only providing this feature as a last line of defense for cheap unprotected cells. Good 18650s have their own built-in protection chip anyway.

Regularly discharging cheap cells to 2.5 volts will destroy them like you said but the OPs project will not use that much power to completely drain a 18650, unless he is planning to use an Ultrafire 10,000mAH crap.:D

srnet: Fair point, although the original post has now been edited.

I have never changed the picture. the only Edit of the first post was to re-explain that I was using a charging board for each battery.

Noobian: You can use a small photoresistor to get the lights to turn on when it gets dark and turn off when it's not.

The TP4056 module has a discharge cutoff function that stops the battery from providing power when it's charge is too low to prevent any damage to the battery.

Well, why didn't you say this before. You don't really need 3 batteries for that. A single 2600mAH 18650 has about 9.3WH so it can power you 0.6W LED for about 13-15 hours = more than enough to power your light from for a dusk to dawn. Them Panasonic 3400s will give you well above a 20 hour runtime.

You just have to boost your battery voltage to attain 12V

Just use 1x 5V (2.5W) solar panel for the setup I suggested. 500mA is more than enough to charge a single 18650 cell. At optimum conditions your panel will fully charge a 2600mAH cell within 6 hours.

You don't really need MOSFETs for a 0.6W LED, Transistors will do the job. Just connect that photoresistor to the Transistor.

Watch this example --> https://www.youtube.com/watch?v=eEBMTpxdPiE

My plan was to let the solar panel act as the photoresistor.

So a couple things related to battery capacity. I have some cheapo cells that I would like to use if possible. I am guessing those will be somewhere around 1000mah. With that said I may need significantly more capacity to get through a couple of cloudy winter days.

I have the mosfet in the plan just because that is what I have on hand. I can get something else if it won't do the job though.

onesojourner: My plan was to let the solar panel act as the photoresistor.

That would work if your project is only meant for outdoors. :)

I may need significantly more capacity to get through a couple of cloudy winter days.

I would suggest you use a USB power bank kit as it can both safely charge multiple batteries and also can output at a steady voltage.

I can get something else if it won't do the job though.

Try to get a regular straw hat LED with 3.5V 150mA rating and you don't need to worry about batteries in series or a voltage booster.

This is indeed meant for the outdoors. I need it to be a set it and forget it kind of thing. I am ok with the battery bank idea, but I am not sure I have seen one that will stay on all the time. They usually require a button press to turn on after charging. If you know of one that is different let me know and I will check it out.

I have a few straw hat LEDs that I pulled from a busted headlamp. So that is an option. When the batteries are fully charged would that damage these LEDs?

Noobian: That would work if your project is only meant for outdoors. :)

I would suggest you use a USB power bank kit as it can both safely charge multiple batteries and also can output at a steady voltage.

Try to get a regular straw hat LED with 3.5V 150mA rating and you don't need to worry about batteries in series or a voltage booster.

onesojourner: This is indeed meant for the outdoors. I need it to be a set it and forget it kind of thing.

Ok cool, you don't need a photo resistor for the outdoor project.

I am ok with the battery bank idea, but I am not sure I have seen one that will stay on all the time. They usually require a button press to turn on after charging. If you know of one that is different let me know and I will check it out.

Actually there are models that outputs without a button press. Like this one.

I have a few straw hat LEDs that I pulled from a busted headlamp. So that is an option. When the batteries are fully charged would that damage these LEDs?

Even if the batteries are not at full charge your LEDs will be damaged. You need to add a simple resistor to prevent that from happening. Here, this site will help you choose the right resistor value. Just make sure you set the source voltage to 5 volts since the power bank always outputs at 5v. :)

Noobian: Ok cool, you don't need a photo resistor for the outdoor project.

Actually there are models that outputs without a button press. Like this one.

Even if the batteries are not at full charge your LEDs will be damaged. You need to add a simple resistor to prevent that from happening. Here, this site will help you choose the right resistor value. Just make sure you set the source voltage to 5 volts since the power bank always outputs at 5v. :)

Perfect. I will get one ordered. I love aliexpress.

onesojourner: Perfect. I will get one ordered. I love aliexpress.

don't forget to add a resistor. ;)

Where does the resistor need to be, and why? I am new to electronics and resistors still have me confused.

onesojourner: Where does the resistor need to be

Like this in your circuit replace the 9v battery from the picture with your usb power bank. :)

and why? I am new to electronics and resistors still have me confused.

To limit the current that goes into your led so that it doesn't get damaged.

This site will help you determine the value of resistor you need. LED RESISTOR CALCULATOR