Battery Intervalometer

There have been many posts on this forum over the years asking how to get longer battery life while shooting with an intervalometer.    While there has been a lot of helpful advice offered, I have never actually seen any data about how well each  of the suggested optimization works.  So I wrote a little <Battery Intervalometer> script to do some testing and publish the results here for discussion.

The script collects data in a log file to let you experiment with battery life.  You can selectively enable /disable the following functions.  They are all the tricks I have read about for extending battery life.

• Time between each shot
• Backlight On or Off
• Display On or Off (if your camera supports that - usually because it has an OVF)
• Switch to Playback Mode between shots
• Switch to Sleep mode via shortcut key
• Lock autofocus

There are also some setup parameters :

• Enable logging to a file
• Lens retract delay time in playback mode - if the shot interval is greater thatn the retract delay, the script will switch briefly back to shooting mode from playback mode to prevent the lens from retracting
• Battery stop voltage - useful once you know the effective range of your batteries to allow you to run accelerated testing by stopping at a fixed voltage level rather than waiting for the battery to expire

In addition,  you can terminate any test run by pressing & holding the Menu key.

Through over 10,000 shots and a week of testing,  I've made the following observations :

Test Camera :   Canon A1200 Powershot  (this camera's display can be turned off via the DISP button)
Batteries :         2 x AA Duracell HR6 DX1500 NiMH 1.2V 2000 mAh

I used the same set of batteries, freshly charged for each test, using a Maha MH-C204F battery charger.  In each test, the camera was allowed to shoot until it was shut down by the Canon software for low voltage.

There were two test suites -  one set of test was conducted at a 4 sec per shot interval and the other at a 1 minute per shot interval.

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Test Suite One
Shot Interval :  4 seconds

Trial	Setup	Results
1	no optimization	3013 shots over 3:02 hours
2	backlight off between shots	3302 shots over 3:35 hours
3	display off	4572 shots over 5:04 hours

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Test Suite Two
Shot Interval :  60 seconds

Trial	Setup	Results
1	no optimization	207 shots over 3:26 hours
2	backlight off between shots	253 shots over 4:12 hours
5	backlight off between shots, screen off via power save after 10 sec	566 shots over 9:26 hours
3	backlight off, idle in playback mode	640 shots over 10:48 hours
4	display off	811 shots over 13:30 hours

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I've just started to chart and analyze the data collected and summarized above.  What I've found really surprising was the very small difference between shooting every 4 seconds and shooting every minute on the length of time the batteries lasted (trial condition one in each test suite).

Update : script updated to include sleep mode via shortcut key

That's good work. Unfortunately my last sequence lasted 12 days. The battery didn't last that long, but I have spares and change them. The Pentax WG1 has a slightly larger battery and I'm able to do sequences for about 4 days on a single charge - shooting every 10 minutes. My w90 sometimes doesn't make it through the day, but other times goes a few days. I really want to get my canon to be able to do this. If the battery could make it 18-36 hours I think it could work. Thanks for doing this. I don't know why other camera manufacturers don't add these features. Pentax is the only waterproof camera I've been able to find that does what I want.

Very interesting. Thanks for doing those tests.

How did you turn the display off? Can you do that in a script?

As philmoz pointed out, using the display button or folding the display screen in on the G1X turns off manual focus and focus lock. You can fold it in while holding half_shoot, but it doesn't turn off the display until you let it up. On the sx260, there's no way to turn off the display.

There is a menu power save option to shut off the display on both cameras. The minimum time to shut off is 10 seconds. I believe it's saved as a parameter value. Interestingly, the camera comes back on still in manual focus mode! The could be a good option to use for time lapses with a long delay between shots, and still be able to hold the focus. It works the same on the sx260.

The shut down delay is listed as param #64 on the SD800
http://chdk.wikia.com/wiki/Params
Is there a way to set params? Maybe this delay could be set to 1 second. That way, it would turn off the display automatically between shots (when you release half_shoot).

I wonder if you could wire a DC ammeter into the external battery supply wires?

Very interesting. Thanks for doing those tests.

They are not very complete (and I only ran each trial once) but at least they give us relative numbers. Until now it seems like its mostly been guessing

How did you turn the display off? Can you do that in a script?

The easy way - I have the script keep clicking the delay button until the display status param says its off (or I've done more than a certain number of clicks without success).

As philmoz pointed out, using the display button or folding the display screen in on the G1X turns off manual focus and focus lock. You can fold it in while holding half_shoot, but it doesn't turn off the display until you let it up. On the sx260, there's no way to turn off the display.

I have not actually made any tests with AFL on or off to see how much that matters.  Its on the "roundtuit" list.
So I don't (yet) have a measure of how much power locking the focus saves.  I probably need to do that test with a subject that moves so that the cam has to focus before each shot.  The static shot of my cupboard that I used for all these tests would not tell us much.

There is a menu power save option to shut off the display on both cameras. The minimum time to shut off is 10 seconds. I believe it's saved as a parameter value. Interestingly, the camera comes back on still in manual focus mode! The could be a good option to use for time lapses with a long delay between shots, and still be able to hold the focus. It works the same on the sx260.

Very interesting - the A1200 and my G10 have that too. So does my SD940 - which does not have an OVF and can't turn the display off via the DISP switch.

The shut down delay is listed as param #64 on the SD800
http://chdk.wikia.com/wiki/Params
Is there a way to set params? Maybe this delay could be set to 1 second. That way, it would turn off the display automatically between shots (when you release half_shoot).

Now that would be slick.  I've never tried - maybe you can just write to the param value ?

I wonder if you could wire a DC ammeter into the external battery supply wires?

Did you ever look at these :
https://docs.google.com/file/d/0B08pqRtyrObjbGFMZnRCOUczU0k/edit
https://docs.google.com/file/d/0B08pqRtyrObjbG90RWRfV0VodUE/edit

Pentax is the only waterproof camera I've been able to find that does what I want.

Well at least you have a camera that does what you want. Without a really big external battery or some hardware hacks,  I don't think CHDK will ever do what you want.

If the battery could make it 18-36 hours I think it could work.

I doubt you'll ever make it that long on the internal battery. It says here that the DC10 uses the ACK-DC40 power adapter:
http://www.usa.canon.com/cusa/consumer/products/cameras/digital_cameras/powershot_d10#SuppliesAndAccessories

I bought the generic version of the same adapter for my SX260, and it works great:
http://www.amazon.com/ACK-DC40-Replacement-Adapter-PowerShot-Digital/dp/B003D7PDKY/

It plugs into the bottom of the camera through the battery door, so at least rain water won't run into it if that's an issue. You could probably seal it with some kind of putty if needed.

To get the maximum internal battery time with a 10 minute interval, have you tried setting the power shut down (display off) time to 10 seconds as I described above? According to the data here, that should make a big difference. If you set manual exposure and focus, and be sure to turn of safety manual focus, and then start the script, it should save some power too.

The only other thing to do would be to turn off the backlight repeatedly when shooting a picture, since the display will turn back on for 10 seconds after the shoot_half is released.
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If you can get 13 hours and 811 shots at 1 minute intervals by keeping the display off, you might do a even better with the display off and 1/10 the shot rate.

If you can get 13 hours and 811 shots at 1 minute intervals by keeping the display off, you might do a even better with the display off and 1/10 the shot rate.

I would expect that to vary quite a bit depending on the camera and batteries used.  If I'd used Li in the test rather than NiMH I might have done even better.

The ultimate setting would be to get the display to stay off in playback mode.  In the results above,  the second best  time was with the camera switching to playback mode for 56 of the 60 seconds between shots.  Unfortunately, doing that overrides the "display off" settings so I was not able to do that and keep the display off.

I think the only solution for the camera on times we're talking about is an external battery.

I finally got the right connector for my G1X dummy battery and soldered it up to connect to that 8.4 volt Lithium rechargeable battery I bought (PM85-50). It's a 50 watt hour battery that weighs around a pound (we Americans are too dumb to figure out the metric system). It also says 13,200 mAH (works out to 3.8 volts). Anyway, it's around 7 camera batteries worth of power.

The G1X battery is labeled 7.4 volts, but taking the Canon battery right out of the charger into the camera, it says 8.3 volts. The PM85-50 has an 8.4 volt output, switchable to 5 volts. It charges from 12 volts through a second connector, which you can also use as a 11 Volt output. Anyway, I finally plugged it into the G1X and get a reading of 8.4 volts like it's supposed to. The camera runs fine, with no burned parts from the 0.1 extra volt .

I also have the SX260 external supply. The connection was flaky, with the camera turning off at the slightest pull on the cable at the battery. I thought it was the barrel connector, but I discovered the dummy battery rocks back and forth a little when you move the connector and disconnects the battery connector at the bottom of the compartment, not the external connector.

So I added 3 thin strips of electrical tape, cut across the tape, to the back of the dummy battery on the opposite side of the connector. When you close the battery door, this acts as a spacer. Closing the battery door then pushes the battery tighter against its connector and maintains the connection even when pulling on the cable.

I think the only solution for the camera on times we're talking about is an external battery.

True.   But we are getting a little off topic - I started this thread was to compare the different suggestions for optimizing battery life through camera setup / script code.  Although I guess they also apply to any external battery,  just the time frame is different.

Still, thanks for posting your details.  I'm planning on a similiar solution combined with an outdoor mounting box project I saw described in another thread last year.

So based on some of these posts,  I decide to run another trial at a 60 second interval. This time the camera ran with only the backlight OFF option enabled and it used the camera's built-in Canon power saving option of turning off the display after 10 seconds.   

This results in a shot, followed by the backlight turning off immediately, followed 10 seconds later by the display turning completely off.  For some reason, the green viewfinder LED turns on at this point,  probably Canon's way of letting us know the camera is still running.

The result of this test was 566 shots over 9:26 hours - good but only the third best time out of five different setups!  Placing the camera into playback mode after each shot with the backlight turned off was better  (640 shots @ 10:48 hours)  and of coarse the best was with the display disabled 100% of the time via the DISP button (811 shots over 13:30 hours).