3.7V to 5V Step up

[EngIntoHW]

hi
for a 2nd Arduino uno project, i need to use a rechargeable 3.7v battery and step it up to 5v to power the arduino uno.

i would then connect the 5v from the module to a USB B cable and use it to power the Arduino uno through the USB port it has.

the 5v has to be regulated because i bypass the Arduino uno 5v regulator.

could you please recommend a 3.7v battery and a Step up module?

thanks a lot

 

[rjenkinsgb]

Just look on Amazon or ebay etc. for "Boost converter" and select one that works down to 3V input and 5V output.
Aim for ones that are rated rather higher than you actually need, as often the ratings in such listings are short term peak or plain exaggerated.

Personally, I'd look for this style that has a large power IC:

ALAMSCN 5PCS XL6009 DC to DC Boost Converter 3.0-30V to 5-35V Adjustable Step-up Down Converter Module DC Power Supply Voltage Regulator : Amazon.co.uk: Business, Industry & Science

ALAMSCN 5PCS XL6009 DC to DC Boost Converter 3.0-30V to 5-35V Adjustable Step-up Down Converter Module DC Power Supply Voltage Regulator : Amazon.co.uk: Business, Industry & Science

www.amazon.co.uk

Not such as these that have a tiny surface mount IC:

iHaospace 5 Pcs DC-DC Boost Converter Step-up Voltage Regulator Voltage Stabilizer Adjustable Power Supply DC 2-24V To 5V 9V 12V 28V 2A With Micro USB Input : Amazon.co.uk: Computers & Accessories

Buy

www.amazon.co.uk

I tried some of those and they were not reliable on a load less than half an amp..

Make sure you adjust the output to 5V before connecting the arduino, then check it and adjust again if required once everything is connected.

For a battery, the simplest is an 18650 cell with a holder and use a separate battery charger; they are cheap and readily available, often sold for paintball guns of vapes.

 

[Wp100]

Find I can feed 3v3 + into the Arduinos +5v pin and they will run fine for most applications.

 

[danadak]

Some converters have minimum load requirements, to stay in regulation so be aware of that.


Regards, Dana.

 

[Nigel Goodwin]

Find I can feed 3v3 + into the Arduinos +5v pin and they will run fine for most applications.

You're running well out of spec though - at 3.3V the processor used should only be clocked at 8MHz instead of the 16MHz at 5V.

If you buy Arduino mini's they come as either 3.3v or 5V, with the appropriate crystals fitted.

 

[EngIntoHW]

Thanks a lot electro-tech friends for your help

I'd like to also ask please,
For the Arduino uno, while it is powered by an external 7V-12V supply (through either Vin or the Jack), can it also then be connected to the PC via the USB port and transfer data?
Will the Arduino uno know it already has its power coming from either Vin or the Jack, and therefore once the USB is connected from the PC, it will "cancel" the USB's 5v input and only utilize its data lines? (Not sure what happens to the G.ND at this point)

 

[Wp100]

Yes and Yes,

If you see the Schematic of the Uno, when USB and Vin power are present, Vin acts on T1 and controls the USB supply.

The USB data lines still work when Vin is in use.

https://www.arduino.cc/en/uploads/Main/arduino-uno-schematic.pdf

 

[Nigel Goodwin]

Thanks a lot electro-tech friends for your help

I'd like to also ask please,
For the Arduino uno, while it is powered by an external 7V-12V supply (through either Vin or the Jack), can it also then be connected to the PC via the USB port and transfer data?
Will the Arduino uno know it already has its power coming from either Vin or the Jack, and therefore once the USB is connected from the PC, it will "cancel" the USB's 5v input and only utilize its data lines? (Not sure what happens to the G.ND at this point)

As explained by Wp100, it's perfectly fine and it's designed to be powered by either or both. As for ground, that MUST be there - I use a LOT of serial/USB converter modules, and simply connect ground, serial in, and serial out (mostly with PIC's, but also with Arduino mini's which don't have their own USB converter) - it's fairly rare for me to connect the power as well, as the projects/products have their own power.

 

[EngIntoHW]

Nigel, WP, thanks a lot!!

How about if external regulated 5v is connected to the 5v pin of the Arduino uno, will again it be possible to connect the PC to the Arduino uno through the USB port?

I know that it is not recommended to connect external 5V to the Arduino uno 5V pin, but it was done many times successfully. As long as the external 5V is stable, there's no problem to feed it to the 5V pin of the Arduino uno.

By the schematics,
It seems that the gate of T1 would be LOW, while both sides of the T1 will be 5V.

 

[Nigel Goodwin]

Nigel, WP, thanks a lot!!

How about if external regulated 5v is connected to the 5v pin of the Arduino uno, will again it be possible to connect the PC to the Arduino uno through the USB port?

I know that it is not recommended to connect external 5V to the Arduino uno 5V pin, but it was done many times successfully. As long as the external 5V is stable, there's no problem to feed it to the 5V pin of the Arduino uno.

By the schematics,
It seems that the gate of T1 would be LOW, while both sides of the T1 will be 5V.

Doesn't look a good idea - I would suggest removing the fuse in the USB 5V line.

 

[dw_43521]

Unless individually sourcing a Li-Ion cell and boost converter is a requirement of a student project or similar, a cheap single-cell USB power bank would provide a cell, 5V output, overdischarge protection, an easy way of charging the cell, and possibly a power switch.

 

[EngIntoHW]

Thanks a lot Nigel and DW.

How would you then suggest to use a Lipo rechargeable battery to power the Arduino uno while still being able to use the USB port to download data from the Arduino?

 

[Nigel Goodwin]

Thanks a lot Nigel and DW.

How would you then suggest to use a Lipo rechargeable battery to power the Arduino uno while still being able to use the USB port to download data from the Arduino?

I refer you to post #10

 

[EngIntoHW]

Hi Nigel
Thanks a lot.
Yes i read it, but doesn't the pc need to have control on the 5v line to communicate with the Arduino?
Like for resetting purpose or something else?

But actually,
It'd make it inconvenient to use because when debugging and uploading software to the Arduino uno from the PC, itd be required to either power the 5v pin or reconnect the fuse.


How about using a 3.7v to 9v booster?
Or using 2 3.7v lipos in series?
That is using the Vin

 

[rjenkinsgb]

but doesn't the pc need to have control on the 5v line to communicate with the Arduino?

No, it is a completely separate thing.
USB ports are powered all the time the computer is on; no power control.

 

[EngIntoHW]

Thanks a lot.
And to Nigel too.

Id try it and also try to find a lipo booster to 9v to have both options.
Thats on another thread.

 

[Nigel Goodwin]

Hi Nigel
Thanks a lot.
Yes i read it, but doesn't the pc need to have control on the 5v line to communicate with the Arduino?
Like for resetting purpose or something else?

No, as rjenkinsgb said, it doesn't need the 5V - which is why you can program the mini with just an external ground, serial in and serial out (and it's own power of course).

 

[EngIntoHW]

No, as rjenkinsgb said, it doesn't need the 5V - which is why you can program the mini with just an external ground, serial in and serial out (and it's own power of course).

Hei Nigel,
thanks a lot!

By mini,
Do you mean the Arduino Uno?

If yes, to make sure i understood please
If 5v external power comes to the 5v pin,
It is possible to have a USB cable, which its 5v line is cut off, and program the Arduino as usual?

 

[Nigel Goodwin]

Hei Nigel,
thanks a lot!

By mini,
Do you mean the Arduino Uno?

No, the mini - tiny board with no USB chip on-board.

Getting Started with the Arduino Mini | Arduino Documentation

The first steps to setting up the Arduino Mini

www.arduino.cc

0.72US $ 16% OFF|Pro Mini 328 Mini 3.3v/8m 5v/16m Atmega328 Atmega328p-au 3.3v/8mhz 5v/16mhz For Arduino Driver Ch340g Pl2303 Ft232rl Cp2102 - Integrated Circuits - AliExpress

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[/quote]

If yes, to make sure i understood please
If 5v external power comes to the 5v pin,
It is possible to have a USB cable, which its 5v line is cut off, and program the Arduino as usual?
[/QUOTE]

Yes, but it's easier to remove the fuse.

Here's the mini schematic.

 

[EngIntoHW]

No, the mini - tiny board with no USB chip on-board.

Getting Started with the Arduino Mini | Arduino Documentation

The first steps to setting up the Arduino Mini

www.arduino.cc

0.72US $ 16% OFF|Pro Mini 328 Mini 3.3v/8m 5v/16m Atmega328 Atmega328p-au 3.3v/8mhz 5v/16mhz For Arduino Driver Ch340g Pl2303 Ft232rl Cp2102 - Integrated Circuits - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

If yes, to make sure i understood please
If 5v external power comes to the 5v pin,
It is possible to have a USB cable, which its 5v line is cut off, and program the Arduino as usual?
[/QUOTE]

Yes, but it's easier to remove the fuse.

Here's the mini schematic.
[/QUOTE]

Hi Nigel
Thanks a lot!

For the moment I am using the Arduino uno.

I would like to make sure please that it is possible to do the same for the Arduino Uno?
That is, to cut the 5v line of a USB cable, and while the Arduino uno is powered from an external 5v power,
Then connect the modified USB cable to program the Arduino uno and download data from it?

Thanks