Hi Guys,
I am making arduino remote controlled car with bluetooth HC 05 and nrf24.
I have 2200mah 3s 30c lipo and i want to power my arduino uno using 2200mah lipo.
It is safe to power arduino uno with lipo or lipo will destroy my arduino uno board as well as itself(if any shortcircuit).
I have voltage step down buck converter micro module and i can control voltage but not amps.
On arduino website, 500mah~1Amps for external power supply.
Please help me..

No, because , a 3S lipo has a voltage of about 12.6 volts fully charged. So, it will heat up the board. And, using a current source from 9v and above poses a risk as if you accidentally touch the 5V pin with that battery supply, you will fry the board.
(The maximum voltage that can be used on the board is 12V).

Quote from: AL HAM SHARI on May 08, 2018, 04:52:44 PM
No, because , a 3S lipo has a voltage of about 12.6 volts fully charged. So, it will heat up the board. And, using a current source from 9v and above poses a risk as if you accidentally touch the 5V pin with that battery supply, you will fry the board.
(The maximum voltage that can be used on the board is 12V).

I have voltage step down buck converter micro module and i can control voltage but not amps.
Arduino Listed 500mah~1Amps for external power supply.

Yes, you can. I have been using 2200mah lipo for my autonomous bot for powering both motor drive as well as for Arduino with the help of  Bug converter (DC to DC step down) to convert the voltage from 12 to approx 4.8V and it works awesome. You can even lower down the voltage even more to power Arduino mini.

Use an LM2596. It will be useful in other arduino projects as well, in the future.

Quote from: AL HAM SHARI on May 08, 2018, 04:52:44 PM
current source

What exactly do you mean by a 'current source'? I'd say it's the perfect thing for his application. Ain't getting any better.

Simply use 7805 Voltage Regulator IC this is a 3 pin IC with input ground and output. its easy to use just use a Zero PCB and solder the regulator ic on the pcb and the you can use a DC jack and directly connect it to the dc socket of the arduino board. This is also easily available at local electronics shops.

TLDR: Yes with a voltage regulator (7805 or 2596 in between as specified in earlier answers)

Long answer:

A vreg will step down the power voltage to match your requirements. 7805 has fixed voltage and a 2 volt drop. 2596 module will give you a small pot that you can turn to set output voltage. If you use a 7805 based linear regulator with a 3S, you'd be wasting a lot of energy as heat. with a 2596 (a dc -dc converter/buck converter) you will be saving a lot of energy from the battery.  all vregs have an upper current limit. so you need to calculate the entire load current the arduino car will be pulling and stay within specified limits. A 7805 can provide 1.5 A max current with correct capacitors, a 2596 will give you close to 3A at lower voltages

Quote from: girishsarwal on May 12, 2018, 11:01:05 PM
TLDR: Yes with a voltage regulator (7805 or 2596 in between as specified in earlier answers)

Long answer:

A vreg will step down the power voltage to match your requirements. 7805 has fixed voltage and a 2 volt drop. 2596 module will give you a small pot that you can turn to set output voltage. If you use a 7805 based linear regulator with a 3S, you'd be wasting a lot of energy as heat. with a 2596 (a dc -dc converter/buck converter) you will be saving a lot of energy from the battery.  all vregs have an upper current limit. so you need to calculate the entire load current the arduino car will be pulling and stay within specified limits. A 7805 can provide 1.5 A max current with correct capacitors, a 2596 will give you close to 3A at lower voltages

Thanks for reply.
I soldered positive and negative silicon wire(with XT60 connector) to IN+ and IN- of LM2596 DC-DC converter
and adjusted pot to get 5 volts. I am getting 5.03 V from LM2696 but problem is of amps. I am getting 1.3~1.4 amp from circuit and recommended ampere for arduino uno is 500mA~1 amp.
On Stackoverflow, one person said "The Vin pin's maximum current is generally limited by the reverse protection diode, which is rated for 1A".

Note: I used a tiny bluetooth car motor to check the current from LM2596 module.

Just put a IN4007 Diode that ll be good enough as it ll also consume some current. Rest even if you connect the arduino directly it is fine. Its just my suggestion coz I use a 7805 and connect the output directly to the arduino with some capacitors in between, and so far I ve not faced any problems.

Connecting Arduino 'Directly' to a 12.6 v supply is not fine at all. Even at nearly 12 v it heats up faster than when it is in sub 10v.

Quote from: AL HAM SHARI on May 13, 2018, 03:51:20 PM
Connecting Arduino 'Directly' to a 12.6 v supply is not fine at all. Even at nearly 12 v it heats up faster than when it is in sub 10v.

I will power arduino with Vin pin and vin pin can take 5 volts but problem is current 1.4 amps

It's better to learn some basic physics. Only the required current is drawn. If it draws 1.4A, then there's some problem with your circuit.

Quote from: Aravind298 on May 13, 2018, 04:17:37 PM
It's better to learn some basic physics. Only the required current is drawn. If it draws 1.4A, then there's some problem with your circuit.

Thanks for reply.
I done all thing as mentioned & shown in website(from google) to measure current output of LM2696 module.So, i think there i is no problem in an circuit.If any wrong happened with circuit then how multimeter can work? how multimeter can show current on the screen.
I am getting 1.3~1.4 amps from LM2596 module.
I used lipo with LM2596 module to get low voltage which is recommended for arduino.
Voltage Ouptut from LM2596 : 5.03 V
Current Ouptut from LM2596 : 1.3~1.4 V.

What I meant to say was, even if the upper limit of the current output from the lm2596 is 1.4A, only the required amount of current will be drawn. If the application requires 500mA, then 500mA will be drawn. But the maximum current that can be drawn is 1.4A.

I feel you're relating the properties of Voltage to that of Current.

BTW, it's always better to have a higher upper limit for the current draw, since current in low supply is not actually good for a circuit.

Current is never really pushed. It is pulled by a load and hence the term "current drawn". The required amount of current will be pulled by the load in this case arduino car).  However sometimes there is a requirement to push current through circuits (such as charging batteries or constant current sources) in such scenarios a load is that pulls the right amount of current (also known as a current limiting source) is attached and the rest of the circuit is put in series. That'd be equivalent to running a horsecart at a certain speed and tying your leg to it. You will get pulled by equivalent amount of force that the cart experiences

perfect explanation Sir.

that's just perfect....btw, I'm not trying to hog

Hi. Do not connect the input supply through Vin pin. Connect it through the DC Barrel Jack only, coz there is a Voltage Regulator soon after the power supply that ll again limit the current and the current will be even lesser than the supplied one. But more importantly your board will not draw that much current as mentioned in the previous posts. But it is always safe to use the power supply jack rather than Vin. I generally use Vin in rare cases, such as if do not have a DC Jack to connect then I use the Jumper cables to connect it through Vin, but as I said I use it rarely. I suggest you to go through the Power Supply diagram of Arduino.