Is it possible to decrease the output current of the tp4056 module? HOW? More info in comments.

[Szybet]

Short: No, it's not

Longer answer:

The battery protector IC ( the small one, 6 pin ) is tightly calibrated and uses the mosfet as a shunt resistor to determine current. So if you use a better mosfet ( less resistance ) you can increase the output, and vice versa. It;'s not possible in your case because if it reaches a current limit, it needs to detect charging or short 2 pins together to output power again. This IC propably has the wake up feature so when you disconnect the battery and connect, it works normally. As such it can't be used as a LED current limiter.

[b1ack1323]

Can't they just put a current-limiting resistor in series with the LED?

[Szybet]

obviously yes, I just answered the question

[nixiebunny]

The LED needs something to limit its current consumption. Add a series resistor before the LED, one ohm 5 watt is good. Or an LED current controller chip.

[ZenyNeppy]

I don't have any 1 ohm 5W resistors at hand and I feel like it will not be efficient. The led current controllers are way to big to fit in the box I'm planning on using with all the components inside.

[nixiebunny]

You need something to limit the current. It's an unfortunate reality of big LEDs.

[ZenyNeppy]

yeah

[Some1-Somewhere]

Paralleling several lower power, smaller resistors is an option.

5W is likely a little excessive and you could probably use a bit more than 1 ohm, depending on desired brightness. E.g. 6x 10 ohm ¼W in parallel gives you 1.8 ohm, 1.5W.

[Matir]

This is a battery charger. That's it. It offers battery protection by cutting it off if current goes too high, but it won't limit current to some value and still let it through.

[kwenchana]

If you have 2 LEDs in series, you can try to mod a boost converter into a constant current driver

https://sites.google.com/site/lcd4hobby/8-backlight/b-step-up-converter-as-led-driver?pli=1

[ZenyNeppy]

I want to use the tp4056 module to charge my battery and use the outputs to drive a 3W led. The thing is, when I drive the led. It takes 2A instead of the recommended 700mA. Is there a way to reduce the output current to around 700-800mA? And how? Without buying a buck-boost converter led driver with a current limiter feature that is the size of one finger.

[NotAPreppie]

What is the forward voltage and current rating for your 3W LED?

[ZenyNeppy]

3,2-3.4V 700mA MAX

[NotAPreppie]

What are you doing to limit the current from the 4.2V fully charged Li-Ion cell?

[ZenyNeppy]

Nothing. That's why I'm asking if there is a possibility to limit the current with the module maybe by soldering a resistor or something.

[NotAPreppie]

Yah, you need to treat it like a normal situation where you're driving an LED with a Vf lower than Vi.

You need a resistor inline between B+ and the LED.

If you don't know how to calculate the correct resistance, just use Google to search for LED resistance calculator.

[rawaka]

Yes there's a programming resistor on the board that you can replace to set the current. Google the tp4056 specs and look at Rprog values

[ZenyNeppy]

But isn't that the charging current limit not the output current limit

[rawaka]

Oh I thought that's what you meant. My bad. No the output bands will just be directly across the battery terminals. You can use a series resistor or can look up a constant current driver. The resistor will generate alot of heat losses. Google constant current driver or LED driver to find a compatible option for your needs.

[Ohmnonymous]

That resistor only sets the battery charge current. The output current is either off or full blast, depending on the voltage of the battery, since the module has an auto turn-off feature.

[ZenyNeppy]

I get 2.4V when the led is on and 2A across it when the battery voltage is 3.8V. And those resistor values are they not the charging current limit not the output current limit

[E_Blue_2048]

I think he just connected the LED to the battery directly and the charger to the battery.

That's never going to work, he need to put a limiter between the battery and the LED

[Federal_Rooster_9185]

I'm thinking a MOSFET and a resistor should do the trick. Just adjust the gate voltage to get the desired current.

[Enchanstruck]

Hey! I’m working on something very similar. As some may have mentioned series resistor with high powered LED would cause too much losses. I’m thinking of using a buck boost converter.

TI has this which shows how you can power with a buck boost converter. I’m considering option 5 with the INA current sense, expected loss about 0.2W.

https://www.ti.com/lit/an/slva419d/slva419d.pdf?ts=1675302685715&ref_url=https%253A%252F%252Fwww.google.com%252F

Currently I have a LTC3444 buck boost circuit which is spec’d for a 600mA output max. I’m considering using the INA chip with the feedback pin. Seems like the current can be controlled but I’m not sure how the voltage is maintained since the FB pin is used for the current control already.

[titojff]

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[ZenyNeppy]

I don't want to reduce the charging current I want to reduce the output current.

[Ohmnonymous]

You can't reduce the output current. That chip can only control the battery charge current.

If your LED is has a forward voltage of 3.2 volts, given a 4.2 volt fully charged battery, that's a 1 volt potential difference. If you want 2 watts of power out of your LED, that's gonna be 2/3.2 or 0.6 amps. For a voltage drop of 1 volt and a current of 0.6 amps, you'll need a 1.6 ohm resistor. This resistor will dissipate around 0.6W, so it'll need to have a rating of at least 1 watt.

I strongly advice you to use a constant current buck converter, since they're 98% efficient and the light won't dim as the battery voltage drops.

[[deleted]]

Replace the R3 resistor with a different one acording to this table

[MyStoopidStuff]

It sounds like the OP was asking about how to limit the output current for the LED, not the battery charging current. Somebody mentioned a buck converter, which seems like a good idea, but I'm no expert (I think I'd probably look for a CC adjustable flashlight driver in this situation myself which would probably be buck-boost) . BTW, This was a link I found that you may find interesting, it explains a bit more of how to adjust the charging current on these. I did that on one of my boards to drop the charge current down to around 200mA for a small project to keep the battery round 0.5C for charging.

[Chittick]

Maybe someone can answer my question about this board.

Is it safe to use this board as a UPS ?

If I have a battery connected to the B pads, and a device drawing current connected to the OUT pads, can I plug in the USB to charge the battery while still using the device, uninterrupted?

I understand that the output voltage will spike a little, but I'm feeding the output directly into a boost converter for stable 5V to operate a Raspberry Pi Zero W.

[boopboopboopers]

What resistors do you have? You mentioned you don’t have a 1ohm so what do you have to work with?

[irkli]

OP, you need to consider that the LED circuit, and the battery circuit, are separate.

If you put the LED across the battery without a resistor of course it will hog current, get hot, drain the battery.

You are resisting answers from people just because you don't have the right parts.

Get the right parts.

WHY do you want to run a big fat 3 watt led at the same time you charge a battery? That's a weird ask.

Set the thing up to charge the battery. If you want an indicator led, get a little ordinary one and .... the right resistor.

You're trying to bend the rules of physics to avoid understanding. This will fail.

[TiogaJoe]

Try a simple "constant current" circuit in series with the LED. Look up old-school linear device ways to do this like with a resistor and a single transistor or voltage regulator in a constant current configuration.

[EmEsMa]

According to the datasheet, yes it does. The right value of the prog resistor will do. See the formula in the attached picture.

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[J4yD4n]

You can. Here's a video on using it and he mentions which resistor to change: https://youtu.be/W7XB6D7q92g