Arduino battery [SOLVED]

[Shadow Gamer]

Hello,

 

I'm a bit of a beginner to the whole arduino lineup and configuration, so I was wondering if I could get some advice. I need an easy to setup power bank for the Arduino Due (preferably running at 9v, which is the recommended spec) that can last atleast two hours and doesn't break the bank. Could I just use a regular old phone power bank, or do I need something specific? I read something about the I/O of the Due running off a 3.3V, but I'm not sure what the exactly means or if it affects what type of bank/battery I need to use. If it doesn't affect the voltage I need for the bank, what does it affect?

 

I'm using the Due instead of an Uno because I want to accomplish something similar to this: https://www.arduino.cc/en/Tutorial/DueSimpleWaveformGenerator

 

Thanks,

Shadow

[Electronics Wizardy]

how much current ya  puling?

 

a 9v battery or a few(4-6) aa's will work fine

[Shadow Gamer]

Ah, I don't exactly know how much, or how to check.

 

Well, my question was, can I use a power bank solution (something that is rechargable) like this: https://www.amazon.com/KMASHI-20000mAh-Portable-Charger-External/dp/B01738J61A/ref=sr_1_2?ie=UTF8&qid=1493086585&sr=8-2&keywords=9v+power+bank instead of hooking up batteries? If hooking up pure batteries is the only way to go, how would you go about doing that?

[Electronics Wizardy]

5 minutes ago, Shadow Gamer said:

Ah, I don't exactly know how much, or how to check.

 

Well, my question was, can I use a power bank solution (something that is rechargable) like this: https://www.amazon.com/KMASHI-20000mAh-Portable-Charger-External/dp/B01738J61A/ref=sr_1_2?ie=UTF8&qid=1493086585&sr=8-2&keywords=9v+power+bank instead of hooking up batteries? If hooking up pure batteries is the only way to go, how would you go about doing that?

that bank will work, just plug it in with usb

[Shadow Gamer]

Oh really? So any 9 volt thing can just be slapped onto it and the Arduino regulates the power itself? Is there a specific downside to using the bank instead of a battery approach?

 

Also, what was the Due homepage talking about when it said the I/O pins ran off 3.3V?

[mariushm]

 

The circuit board of arduino due uses a switching regulator (a DC-DC converter) to convert anything above around 6v down to 5v. That's how it can run from either usb connectors (5v native) or from DC-In. From that point, some components on the board are powered from that 5v, but the actual processor itself works with 3.3v which is produced by a separate linear regulator (NCP1117-33) which takes its power from 5v output.

 

The dc-dc converter will be happy with any voltage above around 5.5v but to be safe, you should probably have at least 6v.  So you could probably run this just fine with 4 alkaline batteries (not rechargeable, 4 x 1.5v .. 1.65v should give you the 6v) because rechargeable will have voltage between 1.2v and 1.35v so four of those batteries won't give you the minimums you want. Maybe go for 6-8 AAA rechargeable batteries if you want smaller battery pack yet easy to source and recharge batteries.

 

If you don't want to mess with AAA/AA batteries, you could go with two lithium batteries (2 x 3.7..4.2v = ~ 7.5v to 8.5v) or a 7.2v battery pack.

 

The DC-DC converter is fairly efficient (should be over 85-90% efficient at the low currents your projects would use), so the exact voltage doesn't matter that much, unlike with linear regulators (you want input voltage as close as possible to output voltage for best efficiency with linear regulators)

 

I'd recommend staying away from 9v batteries because they have very small capacity (energy) for the size and weight and price.

 

Also.. it would help (the battery) to add a small polymer capacitor (or tantalum, but tantalum is more expensive) very close to the DC jack of your board... let's say 100uF to 220uF 16v..25v polymer or a 330-1000uF 16v rated electrolytic capacitor (basically the voltage rating should be above what you think the maximum voltage will be.. the dc-dc converter chip itself accepts up to 20v.

The dc-dc converter circuit on the board has a 10uF capacitor at the input which is fine if you use a AC-DC adapter but if you use batteries, a bit more capacitance can help reduce the current spikes seen by the battery.

 

later edit:

you can power the arduino using a power bank from a usb connector, the board has no idea that you're using a power bank, it just sees  the 5v generated by the  power bank.

USB power banks typically have a lithium battery inside that has a voltage between 3.7v and 4.2v and there's a boost dc-dc converter which creates 5v and puts it on the connector.  The boost circuit is optimized for higher currents (500mA to 2000mA) so if your project uses let's say 50-100mA, the efficiency may be very poor (let's say less than 70%)

So if you want absolutely the longest life from a battery, you would get better results with a battery (or a series of batteries) that has a voltage higher than around 5.5v and let the dc-dc converter circuit on the board produce 5v with better efficiency.

 

 

[Shadow Gamer]

3 minutes ago, mariushm said:

Also.. it would help (the battery) to add a small polymer capacitor (or tantalum, but tantalum is more expensive) very close to the DC jack of your board... let's say 100uF to 220uF 16v..25v polymer or a 330-1000uF 16v rated electrolytic capacitor (basically the voltage rating should be above what you think the maximum voltage will be.. the dc-dc converter chip itself accepts up to 20v.

The dc-dc converter circuit on the board has a 10uF capacitor at the input which is fine if you use a AC-DC adapter but if you use batteries, a bit more capacitance can help reduce the current spikes seen by the battery.

Sorry, I have no idea what that is, or what just about any of what you said meant. Could you provide an example and explain what a polymer capacitor does?

[mariushm]

Capacitors store energy, just like batteries. They have  + and  -  leads , you connect them between the + and - wires coming from the battery pack, but as close as possible to the DC In jack.

 

Batteries deliver energy to a circuit but have some internal resistance.. they're slow to react to changes in demand from the circuit board. In contrast, capacitors have very low internal resistance so they are super snappy and can give the circuit energy almost instantly making everything easier for the battery. Downside is they can only hold a tiny amount of energy. Think of them like additives to the fuel in your car, in a very simplified way... or think of them like the S in the SHDD drives (the old mechanical hard drives with a tiny SSD chip used to speed up some operations). 

 

Polymer capacitors are just a type of capacitors, you see them used a lot on modern motherboards .. those round towers on the motherboard. Electrolytic capacitors are an older style of capacitors which are slightly less good compared to polymer capacitors (and that's why i recommended those higher values for electrolytic capacitors)

 

Anyway.. you don't have to worry about it if you're really a beginner.  For 2 hours of operation, pretty much any battery (probably even 9v batteries but like i said, they suck) would work.

[Shadow Gamer]

Ah, alright. I assume that only applies to non rechargable or dockable batteries (and requires a whole lot of breadboard work) so I think I'm going to stay far away from that for now.

 

 

https://www.amazon.com/10000mAh-eeco-Portable-Charger-Products/dp/B01NCJUM6K/ref=sr_1_2?s=wireless&ie=UTF8&qid=1493089219&sr=1-2&keywords=7v+battery

I assume this would work, since it is within voltage and can provide enough amps? The specs say the USB Type-A Output is either 4.6-6.5V/3A, 6.5-9V/2A or 9-12V/1.5A, and the arduino fits those requirements. This might be ridiculously expensive, though, I have no idea if this is a reasonable price for a battery of this quality. I've done some searching and I think 7-9v batteries are all very expensive.

[mariushm]

Like I said, you can put batteries in series to get higher voltage. So you could buy a 4xAA battery holder and put 4 regular alkaline AA batteries (not the rechargeable kind)  in it and you'll be fine.

 

no, that powerbank doesn't work like you think.

By default, it outputs 5v on the usb connectors, so if you plug a usb cable from the power bank to the usb connector of your arduino, arduino gets 5v and runs.

Some phones have a circuit in them which can "talk" to a chip inside the powerbank and tell it to raise the voltage it produces to a higher value, like 9v for example. With higher voltage the chip inside the phone can charge the phone's battery faster or more efficiently.

Without exact commands, the powerbank won't (or shouldn't ever output anything except 5v

so the device will power the board but it would be overkill and don't buy it expecting more than 5v.

 

[Shadow Gamer]

Okay. Again, I'm pretty new to the whole Arduino scheme, so I'm probably not going to be doing any extra breadboard connections that will cause more issues if the thing falls apart and take up a whole lot of time just learning how to set it up in the first place.

 

Alright. Could you recommend a power bank that runs off 7.2-8v? I'm having difficulty finding one.

[mariushm]

Oh man.. again.. let's make it simpler hopefully.

 

The Arduino Due can be powered in two different ways.

 

METHOD 1 : It can take power from a USB connector, where it expects to receive 5v. A chip on the board then produces 3.3v for the processor and everyone's happy.

METHOD 2 : It can take a wide range of voltage (between 6v and 20v) through the DC In jack and then a DC-DC converter circuit on the board creates the 5v voltage, and then a chip on the board produces 3.3v required by the processor.

 

So if you have independent batteries (like 4 AA batteries in series, or a 12v lead-acid car battery , or a 9v battery) or some power source that's higher than 5v like a AC-DC adapter that outputs 7.5v or 9v  or 12v  .. you want to use METHOD 2 to power your board.. that is: to connect your battery to the DC in jack on your Arduino

 

If you have one of those power banks, that power bank outputs 5v, so you can use a regular USB cable to create a connection between the power bank and the Arduino and then the Arduino would be powered according to METHOD 1.

You can also use generic phone chargers with that USB connector at the end, those will output 5v as well, so your Arduino would run according to METHOD 1 - it takes 5v from the usb connector and just works. You can also connect the arduino to a USB port on your computer and it will simply work.

 

 

 

[Shadow Gamer]

Thank you, that is so much help! I know some of us newbies are a bit slow, but you know, gotta start somewhere. I didn't even know the Due had two separate power inputs. 

[ArduinoBen]

(For logic, phone power bank would do fine.  If you were powering some sort of motor directly through the Arduino (no H-Bridge with external power supply), you would need something more powerful).

[ArduinoBen]

2 hours ago, Shadow Gamer said:

Ah, alright. I assume that only applies to non rechargable or dockable batteries (and requires a whole lot of breadboard work) so I think I'm going to stay far away from that for now.

 

 

https://www.amazon.com/10000mAh-eeco-Portable-Charger-Products/dp/B01NCJUM6K/ref=sr_1_2?s=wireless&ie=UTF8&qid=1493089219&sr=1-2&keywords=7v+battery

I assume this would work, since it is within voltage and can provide enough amps? The specs say the USB Type-A Output is either 4.6-6.5V/3A, 6.5-9V/2A or 9-12V/1.5A, and the arduino fits those requirements. This might be ridiculously expensive, though, I have no idea if this is a reasonable price for a battery of this quality. I've done some searching and I think 7-9v batteries are all very expensive.

Pretty good price, keeping in mind that it also looks quite attractive.