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 The most efficient power in the lightest package? 
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Joined: Wed Aug 17, 2011 8:07 am
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Post The most efficient power in the lightest package?
I've had the worst luck with power lately when running the Emotimo's TB3. I recently shot time-lapse for a documentary series with Kessler's REV 2 Pan and Tilt Head which seems to use power more conservatively. Kessler's is a great system but I love my TB3 and brought the newly acquired eMotimo to this shoot (powered by Anker's 10000mah batts). The problem is I couldn't finish a shot; it wouldn't shoot more then 3 hours. The temperature was around 0 degrees Celsius at the lowest.

What will it take to run the TB3 for 8-12 hours? I thought about paralleling two Ankers. Tonight I'll test this and see how far I get and tomorrow post the results.

I have this http://www.kesslercrane.com/product-p/ion_battery.htm Kessler batt in my cart, but will it deliver more power? I think the MAH unit is flawed when communicating capacity. I sent Anker an email with my concerns; below is an excerpt from their response. Anyone have any thoughts on Kessler's battery given this info and it's actual capacity?

My post is a bit wordy but all in all I'm looking for the ultimate power system that is light, and has high capacity. Money is no object within reason. Just looking for the best option because running out of power in the middle of a shot is painful. I'd like to run a 12v moco unit, lens heater and camera (via false batt) off of the same power cell.


FROM ANKER:
"As all external batteries in market have conversion loss. Our Anker external batteries have an efficiency of 70% while most of other external batteries in market have an efficiency which is lower than 65%. The built-in battery cell has a voltage of 3.0-4.2V. The PCB will boost it from 3.0-4.2V to 5.3V to give a USB output to charge you devices. This procedure consumes power, plus the power will also drain on the Resistance of the cable and phone's circuit, those makes the anker external battery have an efficiency of about 70%. Therefore, the actual output of this external battery is 70% (3000x70%=2100mah).

Just want to add, according to industrial standard, all external batteries are labeled based on raw cells capacity in external batteries (for this one, it is 3000mah) not efficiency. Like others, we are following this standard."


Thanks in advance,

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Wed Oct 09, 2013 2:30 pm
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Post Re: The most efficient power in the lightest package?
My test tonight. :?:


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Wed Oct 09, 2013 2:38 pm
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Joined: Wed Nov 11, 2009 10:45 am
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Location: Merritt Island, Florida, Estates Unitas
Post Re: The most efficient power in the lightest package?
How did it go? I'm curious how much juice these things eat as well. In this latest test, are you using it for the dew heater, camera and eMotimo, or just eMotimo alone?


Wed Oct 09, 2013 5:01 pm
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Joined: Sat Aug 27, 2011 7:05 am
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Post Re: The most efficient power in the lightest package?
Get the Kessler Ion battery! I have been though so many freeeeeking batteries and finally the Ion has solved all my problems. I shot this entire burning man time lapse film with one charge and still had a bit of battery left! http://www.vimeo.com/ondemand/5335/75660130


Thu Oct 10, 2013 7:42 am
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Post Re: The most efficient power in the lightest package?
Awesome video Daniel, and thanks for sharing your experience with the Kessler battery. That kind of experience is a lot more helpful than specs published by battery manufacturers. Case in point, Scott's Anker batteries claim to have 10 amp hours each, compared to just shy of that for Kessler. Apparently you are getting a lot more hours of use from the Kessler. Makes you wonder how reliable the amp hour ratings are. Normally, it would seem reasonable to compare amp hours per dollar or amp hours per pound. If amp hours is something that gets exaggerated by some sellers, then reviews based on actual use like yours become the best way to pick a good battery.

Are we sure that Kessler's battery isn't significantly more than 9.6 amp hours? I know thats what they say, but Daniel is getting a lot more MOCO out of 9.6 AH than I would have thought possible.

Scott, how much current does your dew heater use? Are you absolutely sure your batteries are starting with a full charge?

Something doesn't seem to add up.

These special packs are real convenient, have the right plugs already attached, a nifty indicator of charge level, and an outer protective case. If you have a medium to large budget, and want to spend your time shooting instead of wiring battery packs, they're definitely the way to go. For DIY guys, there are these Lithium iron Phosphate cells plus battery management circuit things;

This has 10 AH, or about the same as the Anker or Kessler. It costs $70.

http://www.ebay.com/itm/12V-10Ah-Bamboo ... 4aca6999bd

This one has 40 AH, or 4 times either the Kessler or Anker. Its $350 and weighs 13 pounds.

http://www.ebay.com/itm/12V-40Ah-Lithiu ... 27d2c7a1ab

Daniel, have you tried anything like these in your extensive experience with battery packs? Do you think the amp hour specs are as unreliable as the above conversation suggests?


Thu Oct 10, 2013 9:19 am
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Post Re: The most efficient power in the lightest package?
DANIEL:
Great video! How many setups did you shoot? An entire short film on one charge is quite impressive. You didn't use any other batteries other than camera batts?
I'll likely order it. Anyone else have an experience to share regarding the Kessler batt?


Sciencelookers:
Results of my eMotimo and 2 Anker 10000mha (paralleled) are in.

I set up the emtimo to shoot; pan axis set at full rotation over twelve hours with a full tilt (fully down to fully up) also 12 hours.
The eMotimo stopped after finishing 58% of its programmed move. Just shy of 7 hours. Given these results I'd say one new Anker 10k-mha would give me about 3 hours on two axises, proportionality it would be 2 hours on 3 axises (33% less efficient). I would need 4 Ankers to run 3 axises for 8 hours considering the variables below..

75 degrees Fahrenheit (23C).
I ran the eMotimo on accuracy mode.
45 Second interval, 35 second static time for 12 hours.

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Thu Oct 10, 2013 12:52 pm
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Joined: Mon Mar 07, 2011 8:37 am
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Post Re: The most efficient power in the lightest package?
Quick one guys as Scott clued me into this forum post. While paralleling these batteries in this way may seem like you would double the output and run times, this isn't the best way to do it.

The reason is that the battery inside the Anker's isn't a full 12 volts. It is a 3.7 volt lithium polymer battery that is stepped up to output 12 volts. That means a circuit board is doing work to convert the 3.7 volts to 12 volts. Albeit, it is working efficiently - my guess is about 90% or so, but there is still some loss. That is just out of one battery.

On the charging side (input) the Anker is stepping down this 12 volts to a charging voltage - more loss, then the second battery is converting back up to 12 volts for output to the TB3.

So I like the idea and this works in a pinch, but this isn't going to double your run time of a single battery.

So if you primary goal is long run time, I would suggest you move to the low power mode as many axis as possible.

For the pan and tilt side, go to power save mode on all axis - on long exposures you can save a ton. This is because in this mode, we only power up the motors for the move. In the accuracy mode, we keep the motors powered on all the while we are triggering your camera. Technically, holding the motors in a position will get us a bit more accuracy on the shot (I can show you the math), but in practice, you aren't ever going to see this unless you are on a strong zoom lens.

To give you an idea of the accuracy we are losing, we could be off by as much as 8 microstep/444.44 = 0.018 degrees. In our tests we haven't been able to see any differences.

For the AUX axis, the lower power mode will be great if you dolly is on the flats or light slope. You do need hold current if you are moving up a dolly at a moderate to steep angle. This, since the AUX motor draws the most current is you biggest power suck.

I hope this helps. We are starting to get quite a few more power questions now that we have offered these options in our firmware.

Best regards,
Brian

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Wed Oct 16, 2013 7:51 am
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Post Re: The most efficient power in the lightest package?
The truth about amp hours can be found on Wikipedia http://en.wikipedia.org/wiki/Ampere-hour. "It is a unit of electric charge, with sub-units milliampere-hour (mA·h or mAh; often used in rechargeable and disposable battery specifications) and milliampere-second (mA·s). One ampere-hour is equal to 3600 coulomb. The ampere-hour is frequently used in measurements of electrochemical systems such as electroplating and electrical batteries. The commonly seen milliampere-hour (mA·h or mAh) is one-thousandth of an ampere-hour (3.6 coulomb)."

Basically amp hours it is a specification for batteries, but it does not take into consideration real world energy draw in amperes, which is the important factor for us photographers. The Kessler ION battery can theoretically deliver a maximum 14 amps for 41 minutes at 12 volts. But that isn't the real life story. The Kessler battery (and all others) voltage will fall off before that time. If the battery draw in amps is less than 14, then it will last proportionately longer. If the current draw is 1 amp, then this battery could last up to 14 hours if the voltage doesn't matter. The only way for us to really know is to test our gear in the real world.

I am using two Tekkon batteries in parallel, one MP3450i and one MP3450. Each battery is rated at 58 Wh (a better measure of battery capacity). The two in parallel are set up to output 19 volts because this is the input voltage of my ASUS netbook, used for running GBTimelapseEOS. The camera is running on 8.4 volts via a step down buck converter adapter I have made. This setup will run for over 12 hours on these batteries.

As a retired electrical engineer, I recommend that everyone measure the current draw of their equipment, and test it, *before* setting out on a photography session in the field. The old carpenter's rule applies here; "Measure twice, cut once." It is always to best benefit to know and understand. The way to know is to measure. The way to understand is to study the science and do the math.

~David

Incidentally Daniel, that is a very good video.


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Fri Oct 18, 2013 2:09 pm
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Joined: Sun Jul 03, 2011 1:30 pm
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Location: Maine, USA
Post Re: The most efficient power in the lightest package?
Goal Zero's Sherpa 100 packs quite a wallop in ~2lbs. 98Wh (11V, 8,800mAh). I'm not quite sure how long I can run the eMotimo and 27:1 stepper for my DP slider because I'm also running other equipment like a RamperPro, DewBuster, and 12v->7.4v step down converter for the camera at the same time and it's been single digit temps. I also power it via solar during the day (which is much warmer now) to help out.

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Sat Apr 19, 2014 8:07 pm
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Post Re: The most efficient power in the lightest package?
Sorry it took me a while to reply, I didn't notice your comment until today. I use a Goal Zero Nomad 20. It easily packs up and fits in my backpack for hiking. I was going to get a second one and daisy chain it for faster charging at the truck or a campsite, but I may just keep saving my pennies and spring for their new Nomad 100 panel instead. It's a whopper, but quite expensive.

http://www.powerfilmsolar.com/ also makes some good solar panels.

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Sun Feb 21, 2016 6:51 am
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