Arduino Forum

General Category => General Discussion => Topic started by: cloud9 on Jun 24, 2015, 04:05 pm

Title: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: cloud9 on Jun 24, 2015, 04:05 pm
i know it might be a stupid question and has been asked many times before. the arduino has a max input voltage in the range of 7-12 v. but what about the amperage? can it be as high as 10000 mA (i.e. 10 A)?
am asking this coz i got a 9v 10400mAh xaomi power bank, can i use it to power the arduino considering that the arduino will only draw what it needs? what is the maximum possible limit?
i read here(https://forum.sparkfun.com/viewtopic.php?f=32&t=27480) that it can be almost anything. please note, i intend to use either the usb port or the DC barrel(not any pin Vin or Vcc)

Title: Re: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: narzan on Jun 24, 2015, 07:37 pm
Quote
The Xiaomi Power Bank - which works with any phone brand
From what they said, this power bank automatically gives the right amps, It's impossible to give a phone all the 10,400 mAh you will fry it
Title: Re: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: cloud9 on Jun 24, 2015, 08:18 pm
From what they said, this power bank automatically gives the right amperage, It's impossible to give a phone all the 10,400 mAh you will fry it

gr8.thanks. how could i have overlooked such an obvious thing....so the arduino, just like the phone, will draw what it needs and leave the rest on the table, so to speak
Title: Re: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: MAS3 on Jun 24, 2015, 08:31 pm
You can't use the USB port to put 9 volts to the board, it will die instantly.
USB (<v.3) usually can handle 500 mA.
But i'm sure that's not what you meant to say.

The [edit]Arduino's on board[/edit] power supply is what sets the limit here.
It can handle a bit higher current if the fed voltage is lower, but all within limits.

The Arduino can't handle Amperes, you'll have to switch range to milliamperes.

A power supply doesn't push current into connected devices, it supplies as much as the device needs, up onto the limit of said supply.

So you'll be fine with that "power bank".

By the way, the number you are fixating on here, is not what you seem to think it is.
10400 mAh. means 10400 milli Amperes per hour.
So it will be able to supply 10.4 Amps for an hour, or 5200 mA for 2 hours, and so on.
Your Arduino will be running for hours and hours off of this power bank.

It could even be possible that (to keep the same number going on here) 10400 mA isn't available at any time.
Still the unit could be a 10400 mAh unit, supplying 430 mA for about 24 hours.
Title: Re: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: narzan on Jun 24, 2015, 08:40 pm
Quote
By the way, the number you are fixating on here, is not what you seem to think it is.
10400 mAh. means 10400 milli Amperes per hour.
So it will be able to supply 10.4 Amps for an hour, or 5200 mA for 2 hours, and so on.
Your Arduino will be running for hours and hours off of this power bank.
@MAS3 you deserve +1 on this I was searching on it actually  :smiley-sweat:

Quote
The Arduino can't handle Amperes, you'll have to switch range to milliamperes.
but wait really how much amps can Arduino handle?! i still not have this answer
from what I know 1A
Title: Re: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: MAS3 on Jun 24, 2015, 08:58 pm
You need to sift through multiple datasheets to get the information you're after.
The 1 Ampere is probably the absolute maximum for the regulator on the Arduino board.
If you put 15 volts to the power jack and then try the thing to regulate 1 Ampere, it will fail and if you're lucky it will go into thermal shutdown.

The Atmel chip that forms the heart of your Arduino can't handle 1 amp.
It will try if you do not prevent it from that, and it will fail miserably at it.
You might see that black and black aren't the same after trying this.
Title: Re: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: narzan on Jun 24, 2015, 09:23 pm
Thanks for your answer :) other +1
Title: Re: max input amperage arduino uno r3(very newbie question already asked many times)
Post by: cloud9 on Jun 27, 2015, 08:26 am
thanks MAS3, narzan :-)