Caemron
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Will a power supply with a higher amp-age work with the pi?

Sat May 26, 2012 2:29 pm

I finally got my raspberry pi yesterday but unfortunately the cables haven't arrived yet and probably won't until Monday at the earliest. I have an iPad charger that supplies 5.1 volts at 2.1amps but the requirements are 5 volts at 0.7 amps. Will it be safe to use a micro-usb connector to power the device through this adapter?

Thanks,
Cameron

dom
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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 2:49 pm

Sounds okay to me. Too many amps is not a problem, the Pi will just consume what it needs.
The voltage is fractionally high, but within the 5% tolerance (and the cable will probably drop 0.1V anyway).

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abishur
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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 3:01 pm

Short answer yes :-)

Longer explanation: The relationship of amperage and voltage is a lot like a water faucet and a pipe. Imagine you are trying to install a new water faucet for your hose, and to do so you need a pipe to come to it that is exactly 3/4". That's Voltage, the pipe coming to your device needs to be precise (well mostly precise, devices tend to have a +/- 5% tolerance on the voltage so your 5.1 volt PSU won't damage the pi). Now once you get the faucet put on your pipe, you open it, but just a little bit. You get a small trickle. You open it all the way, you get a gushing stream. That's amperage, your faucet only takes as much water (amps) as it needs. So if your pipe can provide more water than your faucet can spit out, it won't hurt anything. The faucet will use as much water as it can and the rest is harmless overhead! Conversely, if your pipe can't provide enough amps, that means your faucet won't be able to put out the full amount of water possible. In the pi's case, this means that you'll get performance issues, or it just won't boot up at all!

So to recap: Be precise(ish) on voltage, a PSU that can provide more amps than the pi uses is a good thing, a PSU that provides less amps than the pi uses means performance issues.
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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 3:06 pm

Caemron wrote:I finally got my raspberry pi yesterday but unfortunately the cables haven't arrived yet and probably won't until Monday at the earliest. I have an iPad charger that supplies 5.1 volts at 2.1amps but the requirements are 5 volts at 0.7 amps. Will it be safe to use a micro-usb connector to power the device through this adapter?
Works fine for me!

The key points are that the charger provides a reliable voltage and that it can meet the minimum amperage requirements (extra is OK). Apple chargers are high quality and should always work fine. Another good charger is the Kindle charger.

Caemron
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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 3:16 pm

Oh perfect thanks! I'll go and set it up now!

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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 4:13 pm

I bought the Nokia AC-10X charger especially for my Pi, as I understand it outputs 1.2A (slightly higher than "normal") - it's been fine for me.
---
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Raspberry Pi Zero W (2018) ("mass") - Raspbian
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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 4:14 pm

abishur wrote:Short answer yes :-)

Longer explanation: The relationship of amperage and voltage is a lot like a water faucet and a pipe. Imagine you are trying to install a new water faucet for your hose, and to do so you need a pipe to come to it that is exactly 3/4". That's Voltage, the pipe coming to your device needs to be precise (well mostly precise, devices tend to have a +/- 5% tolerance on the voltage so your 5.1 volt PSU won't damage the pi). Now once you get the faucet put on your pipe, you open it, but just a little bit. You get a small trickle. You open it all the way, you get a gushing stream. That's amperage, your faucet only takes as much water (amps) as it needs. So if your pipe can provide more water than your faucet can spit out, it won't hurt anything. The faucet will use as much water as it can and the rest is harmless overhead! Conversely, if your pipe can't provide enough amps, that means your faucet won't be able to put out the full amount of water possible. In the pi's case, this means that you'll get performance issues, or it just won't boot up at all!

So to recap: Be precise(ish) on voltage, a PSU that can provide more amps than the pi uses is a good thing, a PSU that provides less amps than the pi uses means performance issues.
That's a pretty good explaination. I just tried it on my luddite son and he got it immediatly

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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 4:24 pm

ukscone wrote:
abishur wrote:Short answer yes :-)

Longer explanation: The relationship of amperage and voltage is a lot like a water faucet and a pipe. Imagine you are trying to install a new water faucet for your hose, and to do so you need a pipe to come to it that is exactly 3/4". That's Voltage, the pipe coming to your device needs to be precise (well mostly precise, devices tend to have a +/- 5% tolerance on the voltage so your 5.1 volt PSU won't damage the pi). Now once you get the faucet put on your pipe, you open it, but just a little bit. You get a small trickle. You open it all the way, you get a gushing stream. That's amperage, your faucet only takes as much water (amps) as it needs. So if your pipe can provide more water than your faucet can spit out, it won't hurt anything. The faucet will use as much water as it can and the rest is harmless overhead! Conversely, if your pipe can't provide enough amps, that means your faucet won't be able to put out the full amount of water possible. In the pi's case, this means that you'll get performance issues, or it just won't boot up at all!

So to recap: Be precise(ish) on voltage, a PSU that can provide more amps than the pi uses is a good thing, a PSU that provides less amps than the pi uses means performance issues.
That's a pretty good explaination. I just tried it on my luddite son and he got it immediatly
I have a mostly luddite father, so I got a lot of experience comparing electronics to other things. :-P
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Re: Will a power supply with a higher amp-age work with the

Sat May 26, 2012 5:07 pm

I just got my r-pi this morning, and was struggling to get it going with my .7A phone charger. I've picked up this 2.1A model from Maplins (currently £12.99) which works a treat: http://www.maplin.co.uk/compact-twin-us ... ply-562310

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Re: Will a power supply with a higher amp-age work with the

Sat Mar 05, 2016 7:00 am

So...

...if I bought one of these (10A) and adapted it to power up the Pi with a mini USB ending, I should in theory then be able to power up a near endless stream of USB devices (sata to usb hard drive included), without having to worry about running out of juice right?

http://www.ebay.com/itm/5V-12V-24V-1A-2 ... lZistzf3SA

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Re: Will a power supply with a higher amp-age work with the

Sat Mar 05, 2016 7:11 am

XD3l wrote:if I bought one of these (10A) and adapted it to power up the Pi with a mini USB ending, I should in theory then be able to power up a near endless stream of USB devices (sata to usb hard drive included), without having to worry about running out of juice right?
The fuse on the Pi3 is (I believe) rated at 2.5A. A higher Amperage PSU will work, but once your power usage total exceeds the fuse rating it will "blow" (and recover after some time). If you want to use power hungry USB peripherals you should use an externally powered USB Hub.

BTW, it's micro USB, not mini.

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Re: Will a power supply with a higher amp-age work with the

Sat Mar 05, 2016 7:13 am

XD3l wrote:So...

...if I bought one of these (10A) and adapted it to power up the Pi with a mini USB ending, I should in theory then be able to power up a near endless stream of USB devices
A three dollar wall wart from Shenzhen city putting ten amps through a microUSB connector doesn't sound like something that will end well.

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Re: Will a power supply with a higher amp-age work with the

Sat Mar 05, 2016 7:15 am

So what if I used one of these to power a USB Hub, would that be over kill?

sarimbinwaseem
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Re: Will a power supply with a higher amp-age work with the pi?

Tue May 07, 2019 8:04 pm

Hey I have a option of 5V and 3.1 Amps .....how this will do....???

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Re: Will a power supply with a higher amp-age work with the pi?

Tue May 07, 2019 9:48 pm

sarimbinwaseem wrote:
Tue May 07, 2019 8:04 pm
Hey I have a option of 5V and 3.1 Amps .....how this will do....???
Didn't you read this thread. :?: :?:

5.0 V and 3.1A will be fine. Read the thread.

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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 12:39 am

Another way to look at the electricity and water comparison is this:

Voltage is the water pressure produced by a water pump.
Amperage capability (as it applies in this discussion) is the size of the reservoir that feeds the water pipe.
Currrent is the actual water.
Resistance is related to the diameter of the pipe.

The size of the reservoir does not dictate the water pressure.

The reservoir can be the size of your house (capable of supplying many amps), but so long as the device that you have at the end of the pipe (say your lawn sprinkler attachment) can handle the water pressure, the size of the reservoir does not matter so long as it isn't too small (and therefore would starve the sprinkler).

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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 5:11 am

lately I've notice there's quite a resurgence of "necromancers" in the forum....
"Don't come to me with 'issues' for I don't know how to deal with those
Come to me with 'problems' and I'll help you find solutions"

Some people be like:
"Help me! Am drowning! But dont you dare touch me nor come near me!"

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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 7:05 am

JohnsUPS wrote:
Wed May 08, 2019 12:39 am
Another way to look at the electricity and water comparison is this:

Voltage is the water pressure produced by a water pump.
Amperage capability (as it applies in this discussion) is the size of the reservoir that feeds the water pipe.
Currrent is the actual water.
Resistance is related to the diameter of the pipe.

The size of the reservoir does not dictate the water pressure.

The reservoir can be the size of your house (capable of supplying many amps), but so long as the device that you have at the end of the pipe (say your lawn sprinkler attachment) can handle the water pressure, the size of the reservoir does not matter so long as it isn't too small (and therefore would starve the sprinkler).
A lot of that is incorrect. The size of the reservoir is not the "amperage capability". The current is not the "actual water" but the rate of flow of the water.

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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 10:29 am

A lot of that is incorrect. The size of the reservoir is not the "amperage capability". The current is not the "actual water" but the rate of flow of the water.
I respectfully disagree.

Note that I said "as it applies to this discussion".
Sure, electrons (or holes, depending on the theory you subscribe to) is the actual current, but like I said, for this discussion.

From a lot of what I have read on this forum, there are many people trying to get even a basic handle on how electricity works. View the definition from that perspective, and you'll see it differently....

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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 11:03 am

@JohnsUPS

You can disagree with as much respect as you can muster but you are still wrong.

The maximum current that the PSU can provide is likened to the rate of flow of water when it is not restricted. The capacity of the reservoir is a volume of water. That determines the length of time that water can be supplied at a given flow rate. That is in no sense like the amperage of a PSU. It is like the ampere-hour capacity of a battery and is not applicable to the discussion in this thread.

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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 11:17 am

JohnsUPS wrote:
Wed May 08, 2019 10:29 am
A lot of that is incorrect. The size of the reservoir is not the "amperage capability". The current is not the "actual water" but the rate of flow of the water.
I respectfully disagree.
Some people (involved in teaching electrical theory) have given up on the water analogy.
I think it is still useful, but only when the correct parallels are used.
In this case @drgeoff is correct, and @JohnsUPS explanation is not very useful.
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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 5:25 pm

It is like the ampere-hour capacity of a battery and is not applicable to the discussion in this thread.
I agree, that is more correct. Reservoir was probably not the best choice of words. Current sourcing capability.

I also agree about the water flow analogy being useful, but only to a point. I generally avoid it.

It seems that many apparently think that connecting a power supply with a high current sourcing capability will somehow damage the Pi, and you know that is not the case.

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Re: Will a power supply with a higher amp-age work with the pi?

Wed May 08, 2019 5:47 pm

JohnsUPS wrote:
Wed May 08, 2019 5:25 pm
It seems that many apparently think that connecting a power supply with a high current sourcing capability will somehow damage the Pi, and you know that is not the case.
Indeed. In explain it often like this:

See the "power supply" as your mains installation in your home. And the mains connection is capable of delivering a serious amount of power when needed. Where I live, a normal group is fused at 16A. But when you connect a phone charger to it. You only draw 0,35A from that connection and there is still 15.65A that you can "use" for other things.
Coming back to your situation, the Rpi takes what's he needs. And as long if the voltage is stable (over the full load range) and you not using more then the maximum current rating. You are safe to go.

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