rakesh219
Posts: 5
Joined: Mon Nov 18, 2013 5:17 am

Time-lapse photography 24 hours???

Tue Nov 19, 2013 12:02 am

Hey! Guys I am sort of new to this whole raspberry pi setup but am very much intrigued by it specially as for the possibility of time-lapse photography. I have two variants in mind on how I want it to perform.....
  1. a. Capture time-lapse images using a sensor for motion.
    b. Capture images non-stop for the 24 hour period.
So setup wise I was planning to have it running on battery for the duration of its run time. I did manage to find a battery with output voltage of 5V/2A and a max capacity of 15.6 Amph. Which by looking up gives me a rough estimate run-time anywhere between 16 hours and 22 hours depending on current drawn. But I am not sure if I calculated it right so would love to get some feedback on this.

The tools for this project that I plan to buy are
  • 1. Rpi Model B (rev 2.0)
    2. Camera Module
    3. Limeade Battery Pack (15600mamp)
    4. Rpi Clear Case
    5. HC-SR501 Human Sensor Module Pyroelectric Infrared
    6. Class 10 8GB SD Card
I did look into initially using a 12V li-ion battery but this would require me to have a heat sink and a fan to remove any excess heat. Thereby making the rig a little larger than needed. What I am curious to know is that is this setup even possible to run for close to 18-24 hours at a stretch taking a pic every 2 sec and would the system be able to handle it, ie storing the pic that rapidly. And could I be directed to a noob friendly guide to making this possible.

Thanks! Really looking forward to this :)


fuffkin
Posts: 92
Joined: Thu Mar 07, 2013 10:50 pm
Location: United Kingdom
Contact: Website

Re: Time-lapse photography 24 hours???

Tue Nov 19, 2013 1:12 pm

Could you use a Model A rather than Model B? That would give you a significantly better run-time.
Sleepy Pi - Extend RPi battery life with a plugin Power Management & Arduino I/O board
http://www.spellfoundry.com

fixitsan
Posts: 58
Joined: Sun Sep 29, 2013 4:28 pm

Re: Time-lapse photography 24 hours???

Tue Nov 19, 2013 1:18 pm

Looks reasonable enough with a caveat or two
Apart from ignoring the use of SI units ;) I think you should see over 15 hours of runtime.

But bear in mind that battery packs with a rating of 15600mAh (mill amp hour) will not produce that much energy at the output once it is stepped up to 5V, due to conversion (in)efficiencies. Overating your capacity requirement by a factor of 1.3 should keep you safe there.

To keep power consumpption down, why not use the Pi's I/O to switch a transistor to gate the supply to the peripherals, so that the camera isn't always powered (maybe it can already be switched via it's own bus, I'm not sure)

And as others have said, using a model A (if you can) will definitely improve run time (or reduce the required amount of battery capacity)

rakesh219
Posts: 5
Joined: Mon Nov 18, 2013 5:17 am

Re: Time-lapse photography 24 hours???

Tue Nov 19, 2013 8:34 pm

Thanks for the links! And sorry about my usage on the SI units :) . I was all over the place.
Well I placed my order but sadly it was before I came across the recommended choice of Model A.

fixitsan, the battery I purchased stated these deliver an output of 5V/2.4A max/port, 5V/4.2A output total. And what really caught my attention was the pass-through charging feature! Here is the link to the product page off amazon.

Well I guess since its been already ordered I will do a series of test with the battery and the (Rpi + wifi) w/ and w/out the camera module to observe the runtime. Also I have come across a way to disable the TV output saving me little power but I am still on the hunt for a way to switch off only Ethernet port but leave the USB functional as I have located a way of disabling the LAN9532 chip. I have come across this link and it states that it disables the on-board Ethernet, but it only applies to the use off the Atrix Lapdock. I will give it a whirl to see what happens. The other link I came across is this. Lets see how it goes!

fixitsan, could u please elaborate a little as to how one would use the Pi's I/O for power regulation?

Thanks! :D

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5398
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: Time-lapse photography 24 hours???

Tue Nov 19, 2013 8:48 pm

I believe if you set gpio 6 low, you will hold the LAN chip in reset which results in very low power consumption.

fuffkin
Posts: 92
Joined: Thu Mar 07, 2013 10:50 pm
Location: United Kingdom
Contact: Website

Re: Time-lapse photography 24 hours???

Tue Nov 19, 2013 9:02 pm

I reckon you're going to be pretty close to your target 18-24 hours with a 15.6AH. For example, if your Pi takes 0.5A then that's around 30 hours runtime.

My model B seems to run around 0.44A with wifi but no camera, so add in a bit for the camera and you're probably close enough to suck it and see (with a strong chance of success).
Sleepy Pi - Extend RPi battery life with a plugin Power Management & Arduino I/O board
http://www.spellfoundry.com

gordon77
Posts: 4465
Joined: Sun Aug 05, 2012 3:12 pm

Re: Time-lapse photography 24 hours???

Tue Nov 19, 2013 9:15 pm

fuffkin wrote:I reckon you're going to be pretty close to your target 18-24 hours with a 15.6AH. For example, if your Pi takes 0.5A then that's around 30 hours runtime.

My model B seems to run around 0.44A with wifi but no camera, so add in a bit for the camera and you're probably close enough to suck it and see (with a strong chance of success).
The pi camera reportedly takes 250mA

fixitsan
Posts: 58
Joined: Sun Sep 29, 2013 4:28 pm

Re: Time-lapse photography 24 hours???

Tue Nov 19, 2013 9:23 pm

Yes, regearding the switching of peripherals, i am talking specifically about the off-board hardware peripherals, the camera and the pyro sensor in particular.

You could try connecting the +ve pin of the pyro sensor to 'Pi +ve 'via the C-E pins of an PNP tranistor. The base of that transistor could be connected to the Pi's GPIO so that when you want the pyro sensor to be active just turn the transistor on to connect the pyro's supply to the Pi's supply. When the transistor is off the pyro sensor would be drawing no current. It doesn't look like a power hungry module but sometimes every little helps.

The camera module is another possibility. Talking off the top of my head here because I haven't so much as glanced at the camera datasheet yet, but if there is nothing in the Pi's config files to allow you to kill power to the camera when it isn't required then you could break into the +ve line to the camera and use a PNP transistor to control power by switching it's base via one of the Pi's other GPIO pins.
If you can turn the camera power on and off via Pi commands directly then even better. Yoiu would just need to allow a small delay for the camera to initialise before asking for an image from it.

You can get dual mosfet powerswitches in an 8-pin dip for less than £1, with very low on-state resistance (RS, Farnell etc stock them). One of those would be handy to switch these two items on and off.

The battery pack looks reasonable, although I would be surprised to see it provide 15.6Ah useful capacity at 4.2 A after 50 cycles. Time will tell there :)

Chris


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