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EasyCam – low cost, solar powered timelapse camera system

March 9, 2010

The Easy Cam on site at Rio Mesa

Update: Project photos here

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In addition to the field and greenhouse versions of the Gigavision camera, we just started development on another camera system for Borevitz Lab.  The goal is to create a low-cost, solar powered timelapse system using relatively cheap Canon powershot cameras running the CHDK firmware scripting tools.  Justin will have a team of undergrads out in the Dunes this summer that can collect data, so we were thinking it would be great to be able to stick out a bunch of smaller cameras to collect timelapse data around the field site in the Dunes.  Since the students will be going out there weekly, the cameras don’t have to be rock solid, they just have to mostly work.

Target System Specs

  • Low power: 10w, 12v solar panel (or smaller)
  • Frame rate: 12 images an hour, ~200 per day (One image every five minutes, +/-16hrs a day)
  • Time-range: Sunrise to Sunset.
  • Image Resolution: 12MP or greater
  • Small and low profile
    • The area where the cameras will be installed is public and so the cameras need to hide easily out of site. This means a small housing and as small a solar panel as possible.

Power requirements

The solar panel and batteries will need to generate and store enough power to run the camera for a full day plus a couple more days to make up for any rain days.  My ballpark estimate for power generation is about 2Ah/day. This is based on a couple of guesses… 1st, the 1Ah battery packs are listed as being able to shoot about 300-700 images.

Estimates of images per charge seem to vary. Canon says 2-300 or so but some of the NB-4l batteries advertised on Amazon say 700. I’m guessing the high end estimates are for with the viewfinder off which is fine for our application. So lets assume 500 pics per 1AH battery. If we assume the battery is only half discharged before it is done then the camera uses about 500mA per 500 pics or 1mA per pic.

I haven’t had a chance to test how much resting power the camera uses, so lets round the power usage per pic by 1.5 to 2.5maH per pic.

Assume 200 pictures per day (1 picture every 5 minutes for 16 hrs a day in the summer). So we need at least 2.5mA * 200 = 500mA per day. I’d guess this was a low end estimate since I seem to remember running my Canon DSLR shooting timelapse all day and it only got about 4-5 hours on a battery, although it has higher power requirements.

A 10w,12v panel will produce 10/12 = 833mAH in full sun for each hour there is full sun. So 10w is probably a reasonable size for the panel if we only need 500mA – 1Ah of power per day.

System power/Batteries:

Since the camera only needs around 3.5 – 4.2v input, I settled on this lead-acid battery for the first battery:

http://www.batteryspace.com/sealedleadacidbattery4v45ahs.aspx

Unless I can find a nice low voltage charge controller that has a timer on it, I’ll probably eliminate the charge controller all together and so using a lead acid (LA) battery give us more leeway in designing the system. LA batteries can handle a lot of abuse and overcharging and should be fine for this application since we don’t have any weight requirements.

Camera power

The Powershots cameras typically take an AC power adapter system that costs about $35 to $$50 and comes with an AC plug and a hollow battery coupler that fits in the camera to replace the battery. For DSLR cameras, you can buy just the battery coupler if you want to run the system on DC power or an external battery, but for the powershot cameras there doesn’t seem to be any way to buy just the hollow battery. This means you have to pay $40+ just to get a cheap piece of plastic and then throw out the AC adapter part since it isn’t any use for this system. In the interest of the DIY spirit, we tried building a fake battery adapter and it was pretty easy to do. It doesn’t look particularly high-tech but it is solid and works great.

Instructions and pics of prototype are here:
http://www.flickr.com/photos/timescience/sets/72157623581979614/

System Timing

Ideally the system will wake up in the morning at first light and shut off at night when the sun goes down. For now it seems easier to just have the camera on all day rather than to wake it up and shut it down every 5 minutes. Also, based on my limited research I have yet to see an off-the-shelf 12v timer system that can be set to turn power off and on every 5 minutes for a whole day. Also, it seems like power cycling the camera 200 times a day would add a lot more wear and tear than just leaving it on, particularly since the power requirements are probably low enough that it won’t matter much if we leave it on.

I haven’t finished researching this part of the system yet. Currently I’m looking at the DC-DC-USB system that is a power switch that can be set using a USB connection. There are also any number of charge controller designed primarily for turning lights off an on that may be suitable.  The DCDC-USB has a min voltage output of 5v so this may be an issue if we are using a 4v battery, although there is a comparable 6v battery we could easily upgrade to. The 6v battery is somewhat bigger though so it would be nice to go with the smaller battery.

Camera Selection

There are a lot of options for cameras, but since CHDK development relies on someone deciding taking the time to hack the firmware for whatever new cameras comes out, there a bit of a timelag between Canon releasing a new camera and when (if ever)  CHDK is available for it. Because I’m shooting for both low cost and a minimum resolution of 12MP, this limits the available cameras significantly because only the most recent set of the sub-$300 range Powershots have 12MP. For higher end ($300 – $400) cameras, the SX200 IS and the G11 both have CHDKs in beta, and the SD990 has an established CHDK. For sub-$300, the only camera available that does 12MP and has a CHDK is the SD950 which ranges in price from $220 – $350 depending on what’s available and whose selling it.

more to come…

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22 Comments leave one →
  1. Mark permalink
    July 12, 2010 3:40 pm

    Any progress on this project? I’m researching a solar time-lapse solution for a house building project, and I was planning on using a little Canon SD700IS with CHDK, but didn’t know how to handle solar battery recharging side of things. Of course I’m also trying to do it on a tiny budget.

    • timescience permalink*
      July 14, 2010 4:37 pm

      Project is almost completed, just haven’t updated the pages yet. We built a board that can handle the charging and switch the camera off and on I haven’t tested it extensively yet but it seems to work. The only issue I’ve seen so far is when the system was in the direct sun all day (90+ degrees outside) and it got too hot and the off on switch didn’t work until it cooled down. it turns on in the AM and off at night. with a 5aH sealed lead acid battery and a 10watt solar panel you can shoot all day. The camera sits in a tiny pelican housing and the solar panel can be mounted above it to provide shade. Total cost for the parts is around $200 I think, not including the camera. It also seems to work pretty well with and Eye-fi card so you can get a live image stream to a server or computer if you have wireless where the camera will be. If you don’t need quite the same image quality you can get an 8mp birdcam by windscapes and a moultrie solar panel to run it. that is a nicely engineered solution if you don’t feel like the fun of a DIY project. They don’t workk with eyefi cards and the images quality is less though (here’s a sample movie from a birdcam – don’t have a comparison one from the camera but the powershots look a lot nicer.)

      I’ll post pics soon. give us a call or email if you want more details sooner (contact info here: http://www.time-science.com) and I can send you a parts list.

      • November 23, 2011 11:48 am

        Hi, I have read all of the info on creating this solar powered camera. I want to use a ricoh digital camera which uses a 3.7v battery. It has intervelometer programmed in it which I would like to use as time lapse camera on my farm.
        Is it possible for you to kindly send me a parts list and any other info you think might be useful to me?
        thank you

        Dee

      • timescience permalink*
        November 23, 2011 12:27 pm

        You’ll need to establish that your camera can be run from external power (not all cameras can do this). You’ll also want to make sure that it restarts after power loss. This isn’t essential if the cameras is somewhere you can keep an eye on it but for reliable, unattended operation use this is very important. On canon point and shoot cameras you typically have to glue or lock down the Play or Power buttons to get the camera to auto-restart after power loss.

        You can buy a DC power regulator to get the battery power to the correct voltage for the camera here:
        http://www.dimensionengineering.com/

        You’ll probably want to get a 5 or 6v battery from somewhere like http://www.batteryspace.com/ to run the camera. Or if you have a spare charge controller and small solar panel already you could just plug them into a 12v battery and use the DE voltage regulator to drop the power to 3.7v. You may also be able to find a 12v car adapter setup from ebay or radio shack, then wire that directly to a 12v battery and your all set on the power end of things.

        Unless your camera has a power-plug adapter built into it, you’ll need to buy a “DC coupler” for the camera – this is essentially a hollow battery that delivers incoming power to the camera from an external source. If you can’t find one you may be able to make one yourself (e.g. http://www.flickr.com/photos/timescience/sets/72157623581979614/comments/). However if the camera isn’t designed to use one of these there will probably be an issue with getting the cord in through the housing to the fake battery… modify the camera at your own risk :) It can be hard to find DC couplers for some cameras. I’ve had to buy the entire AC adapter kit just for the coupler (e.g. http://www.amazon.com/SterlingTeks-POWWER-Ricoh-Power-Adaptor/dp/B002WV6SJ2/ref=sr_1_14?ie=UTF8&qid=1322075392&sr=8-14. This is a waste of hardware but is handy because you can cut the power tip off the AC adapter and use it with your battery system. Check on ebay as well once you figure out what keyword searches to use to look for the coupler for your camera. Also note that some of the AC kits (like the one linked above) don’t actually ship with the DC coupler part that you need in the camera to make it work.

        Once you have DC Coupler (hollow battery), to get the right tip size for the power tip that goes into the camera/coupler, the easiest thing to do is go to radio shack and try out all the mini power tips they have until you find the one that fits. You can buy it there or take down inner and outer tip dimensions and buy some pre-wired wired tips from somewhere like DigiKey.com

        Once you get the external power part working, if you buy one of the adjustable DC power regulators from DE, you can use it to find out the functional voltage range of your camera by slowly adjusting the voltage going to the camera to see when it turns on/off. For example on Canon DSLR’s the usable range seems to be about 7.4 – 8.1 volts which is handy to know.

  2. Mark permalink
    August 13, 2010 11:21 am

    Hey Guys,

    I’m still after that parts list if you’re still offering :-)

    Cheers, Mark.

  3. August 25, 2011 3:39 am

    How did you get over the memory card space issue? (The Eye-Fi only deletes images while the cameras rebooting – so the card will fill up).

    Cheers,

    Gareth

    • timescience permalink*
      August 25, 2011 4:29 pm

      We used a regular SD card in that system which was swapped out in periodic visits to the field. This makes it less user friendly though because you need two SD cards that work with CHDK and if you have an undergraduate student going out, they can’t always be relied on to get the camera working after swapping the card out.

      About the eye-fi card – we didn’t have a chance to test it extensively with an eye-fi but my understanding is that the eye-fi will delete after the power is cycled. since the camera power cycles every night, this wouldn’t be an issue. We’ve had limited success in field trial with the Eye-fi so I wouldn’t count on this working unless I saw it myself.

  4. September 29, 2011 12:41 pm

    Did you ever get any further with this project? I am a research intern with the Office of Sustainability at Western Michigan University and we are looking to do something similar and I would love to hear how your project turned out

    • timescience permalink*
      September 30, 2011 9:45 am

      We got the whole thing working and it worked pretty well but we found it a bit to complicated to be reliably serviced by undergrad students. It can be tircky to get the CHDK working on the cameras and if something goes amiss when they go out to swap out SD cards they have a hard time debugging it to get the camera working again. Also, unless you happen to have a bunch of cameras on hand, it ends up costing about the same to build an EasyCam yourself as to buy a birdcam from wingscapes or a similar game camera with a solar panel. Since the cost was the same and the birdcams are easier to use and more reliable, we decided to use those over building more of the EasyCams ourselves. That said, the CHDK is not that hard to use so if you have someone in your lab who is technically adept and likes doing stuff like that, they can pretty easily keep things going. The Canon camera in the EasyCam system do take much better pictures than the birdcams and there is the added benefit that since the camera is on all day it works with an EyeFi card so you could potentially set up a wireless camera network if you have a mesh network at your site. We’ve done this in the lab (not yet in the field) and it worked really well. You can’t use EyeFi cards with game cameras because they don’t stay on long enough to power the card to upload images.

      We do have a few extra circuit boards and I have the parts on hand to build a couple of full systems if you want one. We could also send you the circuit diagram to build more of the power boards or you could order them from our designer. I think they were $20 or $30 a piece when we ordered 5.

  5. Dee permalink
    November 15, 2011 4:49 pm

    what does CHDK do for the system?

    • timescience permalink*
      November 23, 2011 12:06 pm

      The CHDK works with canon point and shoot cameras to let you program them to do stuff (more info here: http://chdk.wikia.com/wiki/CHDK). In this case we use it to enable them to do timelapse. If you have a different brand camera that already does timelapse or an intervelometer, you wouldn’t need it.

  6. riveryeti permalink
    March 18, 2012 1:31 pm

    FYI I have a working system with Eye-Fi and CHDK running in the cloudy/rainy Pacific Northwest using Canon SX30 and SX220 cameras, with a similar solar/battery setup. We built a board that drops the voltage down for the camera and mifi and power cycles every 4 hrs.

    For the moment I am using CHDK-side scripting to delete images without making sure that they’re uploaded (free-space threshold is user-defined, and so is number of pics – it deletes oldest images first).

    The chdk script is posted here. Sorry I haven’t worked it all up into a page or anything. Not much spare time these days.

    http://chdk.setepontos.com/index.php?topic=5139.msg83013#msg83013

    • timescience permalink*
      March 18, 2012 2:03 pm

      Wow, you’re the first person I’ve hear of that’s got the eyefi working with chdk to delete. Nice work! There’s about a million people on the eyfi forums looking for that solution. I got an eyefi working with an intevelometer and a CLEAR modem (details here: http://forums.eye.fi/viewtopic.php?f=2&t=5849) but I didn’t think it had been done with the chdk yet.

      Are you really using a mifi? How’d you hack it to power cycle? When we tested it, it wouldn’t turn on again after the power had gone out so it didn’t seem like a usable solution.

      • riveryeti permalink
        March 18, 2012 3:07 pm

        Hacking the mifi 2200 to power on again after a power cycle was pretty easy. You just have to clamp the button down. BUT it has to be the 2200 (3G only). We tested a mifi 4510 unit, but it didn’t behave the same way. If you hold the button down, it goes all the way to shutdown mode.

        For our purposes, the trickiest part of the mifi was that we wanted to conserve power by having it go into sleep mode after a couple minutes of inactivity. If you want it powered up all the time you can just power it via the USB port, but it won’t sleep that way.

        What we did in order to get it to sleep after the configurable period of inactivity was to build a dummy battery and power it through that. I used contacts from old cell phone batteries and measured the resistance on the two middle contacts to figure out which one was the thermistor and which was the battery ID resistor – then put resistors using about the right value in.

        Will try to post more details to that eye-fi thread you linked in your reply, but I have to go troubleshoot a camera right now (we’re trying to get 7 of them up and running).

      • timescience permalink*
        March 18, 2012 4:07 pm

        Nice work on the mifi hack. We did a similar fake battery for the canon, worked way better then I expected. (http://www.flickr.com/photos/timescience/sets/72157623581979614/)
        After testing the mifi we just gave up and used usb modems but we had computers on site so it wasn’t a big issue. If you are in an area with CLEAR coverage, they are a great deal. $35/mo for unlimited bandwidth. Their household rated modems have ethernet and wifi and 12v input. The one we’re using is on AC power though so I’m not sure how their power usage is, probably not that great for solar, but you can’t beat the price.

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