running canon a620 via UPS (Uninterruptable Power Supply) - Hotwire! Hardware Mods, Accessories and Insights - CHDK Forum
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running canon a620 via UPS (Uninterruptable Power Supply)

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Offline yair

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running canon a620 via UPS (Uninterruptable Power Supply)
« on: 18 / May / 2009, 14:45:09 »
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i want to run a 48hr time lapse on batteries
i have here a UPS (currently broken, i need it replaced) with following spec:

  • rated power supply: 650VA/400W
  • internal battery: 12V 7Ah

i understand that the A620 will probably take about 500 25-30 mA when shooting without screen and at manual focus (based on the CHDK power consumption page).

now, how long will it to run on PSU based on it's spec at 3-4 frames per minute ?
nothing like actually testing, which i will as soon as i get it. but would appreciate some guesstimations.



related threads:

Using chdk to measure the internal resistance of the batteries in the camera - guess i was way optimistic about the power consumption while shooting...

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To save battery life time you can switch to play mode, the power consumption is ~ 50% compared to the record mode.
You also can manually turn the display off: in the Canon menu you can assign the PRINT key to "Display Off", then with a LONG keypress (~1-1.5s) on PRINT the LCD shuts off, switching to/from the ALT mode is done by a SHORT (~ 0.5s) keypress to PRINT.
SD870 / IXUS860 battery life for time lapse shots

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enabling manual focus causes the camera to consume 140mA more! Even when i disable the "MF Point zoom" Magnification thing, the additional power consumption stays.
Power Consumption - some Measurements -some more power consumption numbers and revelations

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LCD backlight of A570IS requires 200 mW of power, give or take a 5 % or so.
...
This is significantly better than using the already proven but a bit disappointing AV plug method ... probably because the video output circuitry requires some power.
Backlight disable: Lua/UBASIC commands + power input measurement results

battery use on long (8 hour) intervalometer run?
« Last Edit: 18 / May / 2009, 15:33:17 by yair »
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databoy

Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #1 on: 18 / May / 2009, 23:02:48 »
As long as you have a reliable mains power supply; indefinitely.
A UPS will only run on the batteries when the mains fails.

If you are using a standard off the shelf, AC to DC 12 volt power supply.
The A620 is rated at 6 volts; that means you need a 12 volt to 6 volt regulator.
Half your power consumption will be wasted through the regulator as heat.
If you can purchase a 6 volt power supply even better.

A very very rough estimate:
your camera consumes 3 watts.
your battery is rated at 84 watts.
switched mode PSU are 60% load efficient.
you are virtually not applying any load to the UPS.

In essence your camera will represent a no load to the UPS.

Be aware that most UPS's output square wave not pure sine wave.
You may experience parasitic oscillations, if the loading is not correct.
End result, your UPS and power supply may self destruct.

Quite honestly you would be better off purchasing a 6 volt gel battery and use a continuous charge, regulated charger.
That is the approach they use in the electrical servicing industry, especially in fire alarm and security panels. 
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Offline yair

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Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #2 on: 19 / May / 2009, 03:29:42 »
« Last Edit: 19 / May / 2009, 03:33:37 by yair »
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Offline yair

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Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #3 on: 02 / June / 2009, 06:26:39 »
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Offline Microfunguy

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Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #4 on: 02 / June / 2009, 07:08:13 »
Use two 6V sealed lead-acid batteries with their +ve outputs joined via two diodes.

You can then disconnect one battery to recharge it if necessary without interrupting the sequence.


David
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databoy

Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #5 on: 02 / June / 2009, 11:17:51 »
« Last Edit: 02 / June / 2009, 11:20:27 by databoy »
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Offline yair

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Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #6 on: 09 / June / 2009, 17:06:47 »
thanks Microfunguy for the simple, elegant solution and databoy for the extra reading :)
i'll go with the first and meditate on the second.

missed this replays and hope to return from the trenches with some feedback.

i hope two 6v4amp gel cel will buy me the two days i need for my timelapse. as i dont have the tools to check the real power consumption i'll have to test.


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Offline yair

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Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #7 on: 10 / June / 2009, 05:58:32 »
one quick question, if i use a 12v car battery, can i use a 7806 (6v) regulator (with heatsink) without problems?

why all the trouble? http://www.electronicspoint.com/12v-6v-converter-regulator-t7737.html
« Last Edit: 10 / June / 2009, 06:11:15 by yair »
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Offline Microfunguy

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Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #8 on: 10 / June / 2009, 06:40:06 »
You could but it is wasting a lot of energy.
A commercial adjustable switching regulator is more suitable.
i cannot remember the company but an American source has been mentioned in this and other (model aeroplane) forums.

Will you be plugging into car's cigar lighter or will you be away from the car ?

If away, I would use the 6V batteries.
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Offline yair

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  • A620, A640, A530
Re: running canon a620 via UPS (Uninterruptable Power Supply)
« Reply #9 on: 10 / June / 2009, 12:59:14 »
found some nice article about dc-dc regulators
http://www.rc-cam.com/dc-dc.htm

i dont realy care about the heat as i get tons of amps/hour to make up for any inconvenience, just afried the current is to much or something.

i'm not going to be near a car, got the (used, free!) battery from a car electrician after i told him about timelapses
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