Ikan AC107-S Test

We bought the Ikan AC107-S with adaptor to provide power for the BMCC (http://ikancorp.com/productdetail.php?id=570). Now we're disappointed because in tests with eBay 7.2v 6600 mAh batteries, the camera only ran 25 to 40 minutes.

I did the test by first running down the internal battery completely. Then I used the Ikan to a shoot two-frames-per-minute timelapse of a clock. I expected each battery to last 4 hours (7.2v x 6600mAh = 47.5 wh. The Switronix is 70 wh and lasts 6 hours (?). 6 hours x 47.5 / 70 = 4 hours).

Any idea what the problem is? My math, my understanding of the Switronix, poor eBay batteries?

- Carl
p.s. I wish we'd ordered the Switronix bundle from Adorama for +$100. I tried to change the order, but our camera came in over Passover and shipped before they answered my email.

My son's film website: http://benkadie.com

Switronix 70 does not give 6 hours...more like 3.5.

The BMCC draws about 20W. The batteries you bought should last about 35min.

So...yeah. Just a crappy setup for the BMCC I'm afraid.

EDIT: Your batteries should last longer, but don't forget the ikan is converting your 7.2V battery to 12V, so adjust your math accordingly. You should be getting (at best) 28.5 Wh from each battery.

You see this quote a lot:

While an internal battery on the BMCC will only run for 90 minutes, the [Switronix] PB70-BMCC will nearly quadruple that runtime

Is this saying the Switronix has (nearly) 4 times the wh (watt hours) of the internal battery or (nearly) 3 times?

Anybody know the wh (watt hours) of the internal battery?

Does the 20W that Sean reports vary much (e.g. raw, just viewing, etc)

- Carl
My son's film website: http://benkadie.com

Battery manufacturers runtime claims are akin to auto manufacturers MPG claims. BM Engineer (Kristian I think) stated the BMCC ran an average of 20W. So the math Switronix is using simply doesn't add up. So add variables like how bright you have the LCD set at, the w draw of your SSD, and the fact that you were charging the internal battery at the same time, it's pretty clear why your run time is so low.

It's generally around the 20W mark, this is factoring a maximum 5W draw from the SSD. This may go up a bit of the battery is simultaneously charging (i.e. when it's not fully charged).

I did the test by first running down the internal battery completely. Then I used the Ikan to a shoot two-frames-per-minute timelapse of a clock.

If the Ikan charges the internal battery as other batteries do (like the cheap longer lasting Anker Astro3 I use) this might have caused some part of the disappointment as well.

An update:

We've ordered the Anker Astro3 ($50 on Amazon for, it says, 100 wh, i.e., about 5 hours).

We'll return the Ikan AC107-S. I think my real problem is that eBay batteries lie about their capacity, but name brand Sony-style batteries don't seem to make sense compared to the Astro3.

We tested the BMCC internal battery with a two-frames-per-minute timelapse of a clock. It lasted 1 hour 45 minutes, which I thought was good.

I'll test and report on Astro3 when we get it.

- Carl

I tested the Anker Astro3 ($50 Amazon) last night. It added 2 hours to our run time.

Test:

• BMCC fully charged + Astro3 Full Charged
• Shoot two-frames-per-minute timelapse of a clock

Result:

• added 2 hours = 3 hours 45 minutes (running time) - 1 hour 45 minute (running time, internal battery)

So, I'm disappointed that it didn't add 5 hours (10000 wh/20 watts), but I'm still happy with it for $50. Also, although it comes with a dozen tip adaptors, the plain cord is just the right size for the BMCC.

I'll do an experiment tonight in which the BMCC internal battery will be dead.

- Carl

Again....it's just straight math.

Anker Astro3 is only 3.7V to BMCC 12V. You're only going to get 30-40% of the runtime....

Again....it's just straight math.
Anker Astro3 is only 3.7V to BMCC 12V. You're only going to get 30-40% of the runtime....

Are you sure? I understood that a Watt is a unit of

energy per time

so a "Watt hour" is unit of energy not directly related to voltage or current.

The other unit I've seen on batteries is Ah (amp hour). That is a unit related to current. Because

watt = volt * amp

- Carl

milliamper-hour to watt-hour calculation
The energy E(Wh) in watt-hours is equal to the electric charge Q(mAh) in milliampere-hour times the voltage V(V) in volts (V) divided by 1000:

E(Wh) = Q(mAh) × V(V) / 1000

So watt-hour is equal to milliamp-hour times volts divided by 1000:

watt-hours = milliampere-hours × volts / 1000
or
Wh = mAh × V / 1000

Example
Find the energy in watt-hours when the electric charge is 300 milliampere-hour and the voltage is 5 volts.

The energy E is equal to 300 milliamp-hour times 5 volts divided by 1000:
E = 300mAh × 5V / 1000 = 1.5Wh

also see: http://www.rapidtables.com/convert/elec ... to-mah.htm

A 95Wh brick, designed for heavy video use, is basically a 6400 mAh battery.

In the end, you're comparing a really small 356g battery and expecting it to provide 5 hours of power when a large brick weighing twice as much only provide 4.5 hours. While weight/size isn't a super accurate measure of battery capacity, it's pretty good at represent how much energy you can store.

While time lapses are nice, they don't represent real usage (unless you only do time lapses) so why not set up the camera and record a open scene for as long as you can fill the SSD, erase and repeat until the battery is drained. Ensure you are not getting any dropped frames (which some people have reported while using these small Up-rated batteries) and get a true measure of runtime?

I see my mistake: a misreading. I thought Anker claimed that the Astro3 was 100 WH, but they claim 10000mA at 3.7 volts (that is 37 WH). Thanks for the help with the math.

2 Anker Astro3 seem like a much better purchase than the PB-70.
Actually you can also power your gameboy 16hours per day until your camera arrives.

I have the BPU battery adapter plate from Ikan. It takes 14v Sony BPU batteries or equivelent and is a better option than "up-converting" a 7.4v battery to 12v.

I tested the Anker Astro3 ($50 Amazon) last night. It added 2 hours to our run time.

Test:

• BMCC fully charged + Astro3 Full Charged
• Shoot two-frames-per-minute timelapse of a clock

Result:

• added 2 hours = 3 hours 45 minutes (running time) - 1 hour 45 minute (running time, internal battery)

So, I'm disappointed that it didn't add 5 hours (10000 wh/20 watts), but I'm still happy with it for $50. Also, although it comes with a dozen tip adaptors, the plain cord is just the right size for the BMCC.

I'll do an experiment tonight in which the BMCC internal battery will be dead.

- Carl

How do you rig out the anker? Does it come with a cable that can plug right into the BMC?

2 Anker Astro3 seem like a much better purchase than the PB-70.
Actually you can also power your gameboy 16hours per day until your camera arrives.

Not sure I'd agree...other than the Gameboy perspective

I am interesting to see someone test one of these up convert systems. Like, torture test. I've heard rumours of drop frames to do voltage dips and I'd like to know for sure.

It's still a very light & portable solution if you don't need hours of extra runtime.

Does it come with a cable that can plug right into the BMC?

Yes, the default cable just plugs in to the BMCC. (In addition, it comes with a dozen tips for use with other devices.)

As far as how to attach it to the camera or tripod or rig ... we haven't figured that out yet. It is pretty much featureless.

- Carl

Just buy some Endura's man....youll be to happy with the results. Light and efficient!

I'm an Anton Bauer man, myself...but it sounds like $400 per battery is not exactly up the OP's alley. I hear decent things about the Switronix 70. But, yeah: simple math. And don't forget if you're near a wall outlet the power of the AC adapter (pun intended). I'm sure you're not on a set so what do you need more than 90 minutes battery for, anyway. I get the same time on my DSLR's. Of course I also have the luxury of changeable batteries. For general use you really only need your battery if you're far from juice.

EDIT: of course I go back and re-read the OP's original post and he already went down an avenue or two I mentioned so I cut that out. You should still go with the Switronix.

If you don't mind using the AC adapter....I like this solution. It was designed to power photography monolights...but it Is 14.8V 130Wh Lithium battery with AC output for $240. Extra batteries are $90.

http://www.paulcbuff.com/vm120.php

Plus you can simply mount it to your tripod or rail using their light stand mount.

Frankly, the only downside I see is the the hassle of using the AC adapter & cables. Some velcro ties would sort that out though.