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Battery Intervalometer

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Re: Battery Intervalometer
« Reply #60 on: 23 / September / 2015, 09:45:29 »
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Hi - I am planning to use a CHDK script for a high altitude balloon flight. I am using a Canon IXUS 115. I used the KAP script and I am getting about 80 minutes on the battery while I need about 3 hours. Can I use this script in the place of the KAP script to get longer battery life?
Maybe.

Taking pictures requires energy - each one you take drains the batter a little bit.  There is no way around that.  However, you can somewhat limit most other things that drain the battery.  The principal things that determine how long the battery lasts are :
  • Number of shots taken.  This is a "hard" limit - more shots = shorter battery life.
  • Camera mode in between shots.   Switching to playback mode (or standby if the camera supports it) helps a lot.  However, it can take several seconds to switch and several more to switch back so this only works if you are shooting slowly - say less than twice a minute.
  • Display off.    The kap_uav.lua script already does this (user set option)
  • RAW/DNG off.   Saving RAW/DNG takes longer and consumes more battery life
  • Locked focus.  If the camera does not have to move the focus mechanism before each shot, it saves power.  The kap_uav.lua script already allows you to do that.  (another user set option)
  • Temperature.   Lower = less battery life.
  • Battery age.  Rechargeable batteries gradually loose the ability to shoot for long durations.

I think that's it. After that, your best bet is probably an external power supply / battery.



Ported :   A1200    SD940   G10    Powershot N    G16

Re: Battery Intervalometer
« Reply #61 on: 08 / October / 2015, 10:09:27 »
Thanks for taking the time to do this research, the results are very useful.  I have done long time-lapses msyelf (snow storm) and couldn't get the camera to last as long as I'd like.

I had an idea, that there would be a way to measure each action (focusing, writing file, display) directly by it's energy.  The advantage is, it would be much clearer what's happening, the experiment would be faster and not rely on completely draining the battery, and tell you cross-over points like when playback mode is worthwhile.

I would start each test the moment the battery voltage changes, let it last 10 units, then stop at the last change.  Then use a formula a*x+b*y=10 for two variables and two equations, to solve for the energy used.  For example sitting there doing nothing is X and focusing is Y, test1 is doing nothing, test 2 is continually focussing, plug that into B, well you can work it all out.  From there, relate battery voltage to capacity used, I"m sure this is well researched and you'll have to find the formula.  Probably quite doable if you're good at math.

http://batteryuniversity.com/learn/article/bu_206a_finding_the_optimal_runtime_and_power_ratio_of_li_ion

Apparently you can optimize even further if you use a specific power draw?
« Last Edit: 08 / October / 2015, 10:16:42 by jmac698 »

Re: Battery Intervalometer
« Reply #62 on: 08 / October / 2015, 20:56:03 »
I had an idea, that there would be a way to measure each action (focusing, writing file, display) directly by it's energy.  The advantage is, it would be much clearer what's happening, the experiment would be faster and not rely on completely draining the battery, and tell you cross-over points like when playback mode is worthwhile.
Certainly interesting science.   

Quote
I would start each test the moment the battery voltage changes, let it last 10 units, then stop at the last change.  Then use a formula a*x+b*y=10 for two variables and two equations, to solve for the energy used.  For example sitting there doing nothing is X and focusing is Y, test1 is doing nothing, test 2 is continually focussing, plug that into B, well you can work it all out.  From there, relate battery voltage to capacity used, I"m sure this is well researched and you'll have to find the formula.  Probably quite doable if you're good at math.
I'm thinking that formula is going to need just a little more work for it tell you much.

Quote
Apparently you can optimize even further if you use a specific power draw?
Please let us know what your experiments show?
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Battery Intervalometer
« Reply #63 on: 10 / December / 2017, 11:19:56 »
This is an old topic but I'll add a hardware related reply: I'm using cheap used A560s as intervalometers and there are key issues if you want reliability. It's no good setting up your camera and script to run for days (up a tree?) then finding it crashed after 2 days! These cameras autotest their batteries for short duration peak current as a way (I think) of ensuring that auto flash will fire without crashing the OS. For the camera software whether Canon or CHDK to run reliably, the power source must have a very low source resistance when checked at power on. Reliability problems often relate to battery condition (internal resistance) or battery contact cleanliness. Unfortunately, relying on the camera batteries if they are AA types is very iffy. Even the external power jack is iffy because their center pin is too small and the contact plating may not give a very low resistance. If the camera is running remotely unattended and there's a power glitch, your intervalometer script or CHDK may not recover to your presets, depending on how it is written.

My A560 uses 2 AA batteries. I removed the contact connection plate on the door (2 screws), replaced the 2 AA cells with shorted empty 'dummies' and soldered wires to the top connectors of the dummy batteries (reverse polarity!!). That removed the door plate as one source of contact resistance and the wired connection is now more reliable using a mains power supply with a backup battery. A wired connection to the camera and large external LiIon battery will be more reliable than internal batteries. 3.2-3.8V is o.k.


Re: Battery Intervalometer
« Reply #64 on: 10 / December / 2017, 11:26:24 »
These cameras autotest their batteries for short duration peak current ....
I think you made a great comment in another post today that would help solve most of these problems, so I'll just quote it below. What value did you use for the cap?
I can stop this behaviour by adding a large capacitor to the supply wiring.
Obviously, you want the cap as close as possible to the battery terminals of the camera. What value did you use for the cap?
Ported :   A1200    SD940   G10    Powershot N    G16

Re: Battery Intervalometer
« Reply #65 on: 11 / December / 2017, 09:43:48 »
Quote
I'm planning on a similiar solution combined with an outdoor mounting box project

I'm planning on making a custom bird box with a UV filter glass in one side for the camera to shoot through. The front will have a fake black painted circle to make it realistic.

2200uF @ 6V low ESR switchmode spec. type. Anything over 1000uF would do, I just had it in my box. It obviously won't fit on the camera pcb, although I found some small surface mount caps up to 1000uF. I will still try to see if I can locate their current sensing resistor on the board. All this says to me that if you want to power these cameras 24/7 from an external supply choose a 3-5A switcher type, make sure wires to the camera are thick and short and use screw clamps terminals rather than plugs for power connection. For external battery backup I'll use li-ion polymer as they have low internal resistance. For remote applications it would be nice if these cameras could boot from an external power source, but the firmware doesn't idle in a sleep mode when the power button turns it off.
« Last Edit: 11 / December / 2017, 09:57:51 by voxmagna »

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Re: Battery Intervalometer
« Reply #66 on: 11 / December / 2017, 10:44:13 »
My A560 uses 2 AA batteries. I removed the contact connection plate on the door (2 screws), replaced the 2 AA cells with shorted empty 'dummies' and soldered wires to the top connectors of the dummy batteries (reverse polarity!!). That removed the door plate as one source of contact resistance and the wired connection is now more reliable using a mains power supply with a backup battery. A wired connection to the camera and large external LiIon battery will be more reliable than internal batteries. 3.2-3.8V is o.k.


Sounds interesting. Do you have a diagram and photos of this mod?

Re: Battery Intervalometer
« Reply #67 on: 11 / December / 2017, 15:45:22 »
I will still try to see if I can locate their current sensing resistor on the board.
I'd be curious to hear what you find.  I'd be surprised if they try to measure current draw. I suspect the camera only looks at battery voltage.
Ported :   A1200    SD940   G10    Powershot N    G16


 

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