BMPCC4K power drain problem (+ general battery advice)

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SandroSchreiber

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BMPCC4K power drain problem (+ general battery advice)

PostMon Jan 21, 2019 6:48 am

Hi forum

I have a problem with my BMPCC4K and the power bank I want to use. I postet this earlier to another thread and realized too late that it was about the old pocket.
I used two 20'000 mah Anker power banks with my old BMPCC. They can output 12v and it worked great for years! I could power the camera for about 7h. Now I bought the original BM DC cables and my camera indicates "AC" when I connect the powerbank, so far so good.
But it seems that the powerbank can't supply the power drain. The battery loses its charge and dies after about 30-45 mins. I tested with the original BM LP-E6 and one from Patona. Unfortunately I don't have an original Canon battery (yet).
The powerbank loses about 5-10% over that time.

I use an active Viltrox ef-m2 speedbooster. Could it be that this is too much for the battery? I haven't even connected my T5 and a mic yet!
The Anker outputs 12v 1.5A, could the current be too low?

Has anyone encountered the same problem?

IF my powerbanks should be insufficient, what power solution would you suggest? If find that V-mounts are too big for travelling, but I consider them for working on set.
In another thread Sandeep suggests the XT-20000QC2-PA2-AO from XTpower. But he only could test it with the original pocket.
Is anyone operating his P4K with one of these over several hours?

Any advice is appreciated. Thanks!
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Robert Niessner

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Re: BMPCC4K power drain problem (+ general battery advice)

PostMon Jan 21, 2019 5:23 pm

SandroSchreiber wrote:The Anker outputs 12v 1.5A, could the current be too low?


That is definitely the problem. The camera consumes around 23 Wh or ~2A at 12V.
And if you have a battery inside the camera and supply AC power the battery gets charged too - consuming maybe another 0.5A.
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Re: BMPCC4K power drain problem (+ general battery advice)

PostTue Jan 22, 2019 5:30 am

I've been holding off recommending this option because it requires a proper charging system, requires proper battery management and storage, as well as careful handling (within reason). But since I saw it being used on a rig in Blackmagic's own website, I thought I'd mention it.

One option is to use Li-Po batteries which provide a range of voltage and capacity options, and are relatively inexpensive. Li-Po batteries are usually used in RC cars, RC helicopters, drones and similar, but there's nothing to say you can't use them in other applications. I use them with my slider that I motorised and they work well.

And it appears that some are using these in their camera rigs. The fact that a Li-Po battery provides two power outlets (one is mainly for charging but can be used as a power source) makes them quite versatile. This is the pic from Blackmagic (look closely at the red connector) and a larger view can be found here: https://www.blackmagicdesign.com/au/products/blackmagicvideoassist.

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SandroSchreiber

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Re: BMPCC4K power drain problem (+ general battery advice)

PostTue Jan 22, 2019 6:25 am

Thank you Robert and Ray. I'm glad it's not the camera again.

Does that mean that the camera consumes about 3.2A at 7.2V from an LP-E6?
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Re: BMPCC4K power drain problem (+ general battery advice)

PostTue Jan 22, 2019 6:36 am

SandroSchreiber wrote:Does that mean that the camera consumes about 3.2A at 7.2V from an LP-E6?


You can't put a definitive figure on the power draw, as much depends on the format you're using, what's connected, battery condition and even environmental factors such as cold vs hot conditions. What you need to do is just work out what you get in your shooting situations. Someone might say they get an hour from one battery and another may only get half an hour.
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Uli Plank

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Re: BMPCC4K power drain problem (+ general battery advice)

PostTue Jan 22, 2019 8:36 am

I've been using Li-Po batteries too on several occasions. Yes, they are relatively inexpensive and can deliver pretty high current. But they have a fast self-depletion, so take care to (re)charge them before use.
And you may get some strange looks at airport security, plan some extra time!
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Re: BMPCC4K power drain problem (+ general battery advice)

PostWed Jan 23, 2019 8:28 pm

What if you used a USB-A to USB-C cable to connect the battery packs? Think a current GoPro cable or such.

I'm surprised there isn't a knock out for a dummy battery cable in the door. One other option would be the TetherTools CaseRelay system - it's a LP-E6 with a small battery in the middle plus a standard USB-A to connect to one of the Anker packs. There's a trick to putting/plugging them in the right order, but once you have that it should be everything you want - hot-swap larger batteries.
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Re: BMPCC4K power drain problem (+ general battery advice)

PostThu Jan 24, 2019 3:51 pm

Thanks for all your inputs!

What if you used a USB-A to USB-C cable to connect the battery packs? Think a current GoPro cable or such.

I'm surprised there isn't a knock out for a dummy battery cable in the door. One other option would be the TetherTools CaseRelay system - it's a LP-E6 with a small battery in the middle plus a standard USB-A to connect to one of the Anker packs. There's a trick to putting/plugging them in the right order, but once you have that it should be everything you want - hot-swap larger batteries.


The BMPCC4K can't be powered over USB, only slow battery charging.
Thanks for the suggestion with the Tether Tools device. But the Anker's USB Ports don't supply 12v, only 5v I suppose.

I think I'll give the XT-20000QC2-PA2-AO from XTpower a try. It's not in stock at the moment but I'll report back once I tested it.

Cheers
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Re: BMPCC4K power drain problem (+ general battery advice)

PostFri Jan 25, 2019 4:54 am

I actually bought 8 18650 batteries with the intention of using 4 in series to get 14.8v or so and hopefully power the camera/ssd drive. At about 10whs each, should get about 2 to 3 hours for the camera alone out of a set of 4. There are a few people making some nice rig options for these very batteries. Only thing I am not sure of is if I can just connect the DC cord to it and it works, or if I need one of those small PCBs with the batteries... I think for protection while charging though, so not sure.
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