any recommendations on how to power a raspberry pi like a battery or something similar ?
Not sure I understand the question...you want to power an rpi with a battery? Look up the rpi power requirements, and then look for rechargeable lion batteries and a battery case to hold them?
>>955961
actually I need to power a pi and arduino + 18 servos each servo needs 150ma
>>955967
So... Do the math and buy an appropriate battery? What do you need us for?
>>955974
some help :/
Anyone who tried this may have some good ideas.
I'm not sure if i'll need a voltage regulation circuit too
>>955977
Obviously you need a voltage regulator to supply 5V to the RPi
The servos have a rated voltage as well. So you'll need to either regulate voltage or select your batteries so that they get the right voltage.
How are the servos being controlled by the Pi? USB microcontroller? Is the microcontroller powered by USB? Are the servos powered by USB?
How long does this battery need to last? Are there size, weight or cost constraints?
We need details OP. We can't read your mind.
>>955980
Okey here's what I'm thinking about but feel free to change any part.
I'll need to power the pi with a battery or something.
Then I'll use the pi USB to power the arduino.
the servos are controlled by the arduino but from what I read it's unsafe to power the servos directly from the arduino.
So i'm gonna need to power them from the same battery.
I have an arduino mega and the small 9g servo motors
I've got the pi 3
>>955986
Alright, simplest way to do this is to grab some 18650 batteries (or other batteries if you have them laying around) , work out how much capacity you need (this will determine how many batteries you need), then put them in two in series so you get ~8V. Use a buck module to drop that down to 5V for the Pi. Use a second voltage regulator to supply voltage to the servos and control them my means or relays attached to the Ardurino.
>>955988
You could also power the Pi from a standard USB power bank, but then you would need a separate battery to power the servos.
this is a stupidly easy question to answer:
- goto amazon.com
- type 'usb battery pack'
- look thru the list to find one with sufficient capacity (mAh)
>>955988
*by means of relays connected to the Ardurino
>>955992
He needs at least 2.7A of current for his servos, you'll struggle to find a USB power bank which will put out more than 2.4A
>>955995
The servos won't run at the same time. The maximum number of running servos at anytime would be 9
>>955994
Not enough power. You could power 14 servos off one 2.1A USB port, but 18 is too much.
I suppose you could use two power banks, or find a power bank with more than two ports which was capable of pushing ~3.5A, but that sort of thing is hard to find.
>>955998
You should be fine then.
thanks people :)
Can anyone recommend a good power bank ?
>>956003
Romoss sense 4
>>956004
thanks again
>>956250
I've done this many times. Basically those little cigarette lighter adapters are switching power supplies you can get on auction sites for like two bucks, and can deliver 2 amps.
>>956004
Not OP but interested in this power bank. About how long will the Pi run on a single charge of the power bank?
>>956257
I would estimate about 10 hours, but in theory you could get almost double that depending on what peripherals the Pi was using, and assuming the power bank had its full advertised capacity and very efficient circuitry.
It will still charge my phone three times, and that's after using it many times over four years. It is made in China but claims to use Samsung 18650 cells, and I have no reason to doubt that this is the case.
>>956285
>10 hours
MUCH more than I need! How long do these power banks last before they die? I see amazon gives it 4.5/5 starts but I don't see any reviews that mention the lifespan of the device.
>>956296
Like I said, I've used it for four years and it's still going strong.
OP here.
I'm confused as hell now.
Would that power bank be able to power the whole thing?
pi + arduino + 18 small servos?
OP is a retard.
>>956344
at least I'm a retard that tries to learn
Op what are you going to be doing with those servos?
From what I'm seeing just make the battery packs or just one big one. The idea with the 18650 batteries sound like a great one. And you can get them in rechargeable variants. Either way you do this, it isn't going to be a thing that you can just throw in your pocket, you need to much juice for that. Unless your packets can fit most of the handheld objects in your house all at once, then you're good.
Crap I'm an idiot. I meant to say make a bunch of battery packs or one big one. Sorry, typing on a phone.
>>956355
I'm making an hexapod. so i need something light and not too big and can give enough power to the thing
>>956343
Romoss sense 4 has two USB ports, one 2.1A USB port that will power up to 14 servos at once (you said your servos use 150mA@5V). You said you only needed 9 servos to operate at any one time.
The other USB port on the power bank supplies 1A. This is enough to power the RPi (~500mA), and the Ardurino (less than 500mA) which is attached to the RPi by USB.
>>956361
If you want more power than that, the best way to do it is going to be building your own battery pack from 18650 cells (which incidentally are what's inside the sense 4).
All the sense 4 is doing for you is saving you the trouble of wiring up your own voltage/charging control circuitry.
So here is a few pictures (one more to come after this post) of my one 18650 cell, if you get the of these in parallel you should be just about (if not) good with the pi and servos. You'd just have to hook on some voltage regulators and things, like that one post was saying. But trying to run pi+arduino+ servos is going to need more than 3 cells.
>>956357
Also, you would have saved us a butt load of trouble if you'd just described your project and requirements in the OP instead of making us ask specifically for every relevant detail.
The roll of duck tape while the battery is in the storage case so you'll have an idea on how big a box with two is going to be.
>>956368
Depends on the type of cells and how long you need it to run for. With IMR 18650 cells you could power it with one cell, but only for 5-10 minutes.
>>956365
The Ardurino cannot handle enough power to run all of your servos directly. Not even close. They will need to have their own power circuit. You will need to use relays interface with them from the Ardurino.
>>956377
Yeah, me and a buddy of mine got curious and tested it out. Also there are some of these that put out more voltage than shown on the packaging. Another buddy of mine got those kinds and fried a few off his things. So keep that in mind.
>>956387
cool. All I need now is to find where I can buy them online and they should ship worldwide
>>956376
All the 18650 cells that I'm seeing are all 3.7 (according to the package). And the pi intake voltage is 5v. Now with that "buffer zone" of voltage it can take smasher from 4.75 to 5.25 (horrifically rough estimation without a calculator and forgetting what percentage that zone actually is) means that if you hook up just one of the 18650 batteries up to it, it won't have enough juice. It may... MAY... turn on, but to actually use processes or anything that will make it draw more can damage your cell or the pi itself. I mean you can try if you have more raspberry pi's.
>>956387
Their nominal voltage is 3.7V, but they're 4.2V when fully charged and can get down to 2.5V when discharged. That's why you need a voltage regulator if you're powering anything remotely sensitive.
for the Romoss sense 4 guy
is this legit ?
http://www.aliexpress.com/item/Original-Brand-Romoss-SENSE-4-Power-Bank-Portable-Charger-10400mah-Dual-USB-PowerBank-For-Mobile-Phones/32524678093.html?ws_ab_test=searchweb201556_2,searchweb201644_4_505_506_503_504_10032_10020_502_10001_10002_10017_10005_10006_10003_10021_10004_10022_10018_10019,searchweb201560_1,searchweb1451318400_-1,searchweb1451318411_-1&btsid=3bca9ea3-527b-47f8-b690-6f6315cac0b7
>>956395
I didn't even receive my first pi yet :'(
>>956389
I got mine off of Amazon. But just do a quick search and you'll find them. It isn't as hard as you may think. I thought it was going to be ridiculously hard to find the equivalent of two 123A's. But that's when I found the 18650, it is just two 123A's.
>>956398
Probably?
There's no customer reviews so I can't be sure.
>>956397
Yeah, they do fluctuate that much if you get a bad cell, and that's why my buddy kept frying things. But you can get some like mine that have a regulator in it. I've tested it at full charge and it is at 3.7v and it only dropped down to I think it was 2.9v, but then again I only tested it when I hit that 10 hours of play time. It wasn't completely dead, but with these batteries you don't want to make them completely dead, that's bad juju right there. But that 4.2 voltage is still outside of that "buffer zone" which I just realized it is called tolerance and it is 10% of the required voltage. So the pi takes 5v so you can do anywhere between 4.5 to 5.5 volts without hurting anything.
>>956403
If you just onto Google and search for battery suppliers or battery warehouses, you'll eventually find one that will ship to you.
>>956414
the problem is with the quality. You can never know. That's why I asked here
>>956407
Lithium ion batteries should be 4.2V when fully charged. That is completely normal. If they don't get to 4.2V when fully charged then they are damaged.
2.5V the lower limit for how much you can discharge them before you risk damaging them. So protected cells, or protection circuits will not discharge them below this.
If you keep drawing from an unprotected cell then they will generally drop below 2V, but you probably won't be able to charge them up again after that.
Please read up on batteries before you start handing out advice.
>>956407
For christ sake use a voltage regulator when powering any ICs. That includes computers like the RPi.
Voltage regulators cost like $1. FFS, why would you risk frying a $30 computer to save $1.
>>956441
where do i get a 1$ voltage regulator ?
>>956441
Thank you, for replying to that and solidifying what I've been saying to that nitwit (not op). I was saying that in order to correctly power the pi without any form of damage to either component, the voltage needs to between a certain range, and using just one won't bring it into that range.
>>956435
Nope you're right. I got a little of both things I was thinking of mixed together. The batteries that my buddy was using that were outputting more than expected were his 123A's. He was using two of them to create the size of a 18650 for various things and it was frying them. But mine (as indicated) has a voltage regulator and the setup also won't let me deplete it past the "damage point" of 2.5v. But that still doesn't change the fact that the voltage of just one well charged 18650 is well below the tolerance of the draw of the pi.
>>956463
You can use a boost module to increase voltage to 5V. If you want to use a buck module/v-reg, then you need to use two 18650s.
>>956448
Banggood.com, or make your own.
>>956463
Rechargeable 123A batteries (16340) will often fry devices designed for 123A batteries, since disposable 123A batteries are 3V, and 16340 batteries are 4.2V fully charged.
Both are the exact same size. People make the mistake because they assume that rechargeables are interchangeable with disposables.
what do you guys think about this voltage regulator
http://www.aliexpress.com/item/1pc-Small-LM2596-power-supply-module-DC-DC-BUCK-3A-adjustable-buck-module-regulator-ultra-LM2596S/32582253900.html?ws_ab_test=searchweb201556_2,searchweb201644_4_505_506_503_504_10032_10020_502_10001_10002_10017_10005_10006_10003_10021_10004_10022_10018_10019,searchweb201560_1,searchweb1451318400_-1,searchweb1451318411_-1&btsid=1c2f31a1-f8b6-41b9-8638-f23de902fdc6
>>957229
You'll need to add a heat sink, but it should work. Just be sure to adjust the voltage *before* you attach the RPi.
