Anyone here who has powered raspberry pi with batteries like lipo or alkaline batteries? I need to know how to do it.
Asked
Active
Viewed 392 times
3
-
Welcome to Stack Exchange. I have edited your title in order to meet SE standard. About your problem, could provide us more informations. Specifically: How long your RPi is supposed to work without interruption? – jlandercy Mar 05 '14 at 16:14
-
thanks sir. I need it to work for around 15 to 20 min probably without any interruption. – muneeb Mar 05 '14 at 16:18
-
actually I am working on an autonomous GPS based car which will be controlled through pi... so I want to know that how to power raspberry pi with batteries. – muneeb Mar 05 '14 at 16:24
-
Take a look at: https://www.kickstarter.com/projects/hamishcunningham/mopi-mobile-and-24-7-power-for-the-raspberry-pi This might give you what you need – recantha Mar 05 '14 at 16:30
-
Sounds like a duplicate of http://raspberrypi.stackexchange.com/questions/1360/how-do-i-build-a-ups-like-battery-backup-system – avra Mar 06 '14 at 08:40
4 Answers
2
You will need a voltage regulator to properly supply your pi (PSU @ elinux.org, there is related questions on RPi SE). Additional protections should be considered if you feed through GPIO.
Basically to answer you question, you can use the Peukert's Law as a first approximation:
C = t*I^k
Where k is an adimensional constant ranging in [1.1;1.3] depending of the battery, I is the current drawn (you need to sum all components of your circuit, including your GPS. RPi draws 1A when idle), C the battery capacity (the fundamental specification of the battery with a dimension in A.s) and t the discharge time.
Eg.: t = 1/2h, I = 2000mA and k=1.2 leads to C = 0.5*2000^1.2 = 4573 mAh, then you better to select a 4800mAh battery.
Battery voltage must be chosen accordingly with the voltage regulator you selected. Do not forget that you need a good 5V supply in order to service your RPi.
Caution: LiH battery needs to be handle with care, it may explode and cause injuries. You need a dedicated circuitry to charge and discharge it. If you are not used to, select regular NiCd or alkaline Battery.
jlandercy
- 446
- 2
- 9
1
If you take either of those you need a regulator/BEC.
That said, I have sucessfully powered my Pi with (4) 1.2V NiMh(Nickel Metal-Hydride) batteries, just some cheap 2500mAh rechargeable energizer ones, no regulator needed and safe for your Pi :)
nreich
- 108
- 1
- 4
-
Just curious about it: How long does it shoulder your Pi? How old are those batteries (how many cycles)? Have you experienced some weird behaviour when processing complex jobs (I mean high CPU load)? – jlandercy Mar 06 '14 at 19:31
-
It powers mine for about 3-4 hours. They are about 30 cycles in. I have mine on a custom quadcopter, powering the Pi, my signal receiver and a MUX and 8 pin DIP MCU on a breadboard also. The Pi is sending 4 pulse widths out constantly, so the workload is high and it still works perfect.. – nreich Mar 13 '14 at 16:52
0
As already pointed, battery voltages will decrease with utilization (consumption), so you will need some sort of circuit to regulate such voltage to 5V for the Pi.
Lipo cells (single ones) for example will have voltages around 3,7V so you will need a boost (step up) circuit; putting them in series (say three of them) will give you around 11,1V, so you will need a buck converter (step down).
There is also the case when you may need a buck-boost circuit, since the voltage of the batteries can go below or above (say) 5V. I recommend a UPS I found on Aliexpress, which will recharge lipo's and provide a clean stable voltage output for the pi: https://pt.aliexpress.com/item/32783727347.html .
Also keep in mind that you will need to calculate the quantity of batteries based on how long you want to power your system for. In my specific case I am supplying a Pi 4 + 7" HDMI display (for a total of 7W) for 7 hours on 6s (cells) Lipo.
Clóvis Fritzen
- 373
- 1
- 11
0
Something that works well for me is using a portable power pack as opposed to a battery. These are convenient due to the fact that they can plug up via the usb port, and they are easy to charge. I have a solar powered one thats around 2000 mAh that can run my pi for an hour or 2 (havent timed it just ball parking it). Or recently i got a portable charger that has a 6000 mAh battery that can power it for at least 4 hours (once again just ball parking it). I have tried the battery method before but it seems a bit overly complicated and runs a risk of ruining my Pi. So thats why i opted for this. Anyway i hope this helps you out. I highly recommend this route above any other. Cheers!!!
messyfresh
- 61
- 3