Remove internal battery? (BMCC)

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Daniel Tufvesson

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Remove internal battery? (BMCC)

PostWed Aug 08, 2018 12:06 am

The internal Li-Po battery in my BMCC is getting pretty old and worn down by now and does not keep the camera alive for more than a few seconds.

Instead of replacing it, I figured I would just remove it completely.

Has anyone tried this? Will the BMCC/BMPC still run properly without the internal battery and powered only from external power source? I know the BMPCC does run fine on external power without EN-EL20 battery and I was hoping the same would work for the BMCC/BMPC as well.
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Anatoly Mashanov

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Re: Remove internal battery? (BMCC)

PostWed Aug 08, 2018 1:42 am

Just remove the battery, apply 3-4 charge-discharge cycles (discharge deep to 3.0 volts per cell) and put it back.
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Daniel Tufvesson

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Re: Remove internal battery? (BMCC)

PostWed Aug 08, 2018 8:49 am

Thank you for the suggestion Anatoly. I see what you are aiming at. A few full cycles can indeed revive a cell. At least for a while.

Some warning may be in order here for all readers.

The BMCC/BMPC uses a two-cell Li-Po pack meaning there are two cells in the pack connected in series. The absolute lower limit for a Li-Po cell is 3V so, in theory, the lower limit for the BMCC pack is 3V+3V=6V. But just discharging the entire pack to 6V does not guarantee that the cells are evenly discharged and one of them may end up at a level below 3V. Discharging or charging Li-Po cells outside the safe limits or using imbalanced Li-Po packs is a good way to eventually set your house on fire and kill your pet. Don't. Ever. Do. It.

I would guess that the (dis)charging circuit in the BMCC/BMPC cuts out at around 7.2V-7.4V to leave some safety margin.

In the RC world basically every multi-cell Li-Po pack is equipped with a balancing connector that gives access to each cell so that their charge can be individually monitored and balanced at all times. That means that the packs can be more efficiently utilized. The pack in the BMCC/BMPC does not have that feature and must rely on bigger margins to keep all cells in the pack within safe operating range.

That being said I would much rather just get rid of the BMCC battery entirely and have one less thing to worry about.
Shoot - BMCC | BMPC | BMPCC | BMVA
Edit - Debian Linux 9 | Resolve Studio 15.2 | i7-3930K CPU | X79 MB | 32GB RAM | GTX1080 GPU | Decklink SDI
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Rakesh Malik

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Re: Remove internal battery? (BMCC)

PostWed Aug 08, 2018 4:28 pm

Daniel Tufvesson wrote:That being said I would much rather just get rid of the BMCC battery entirely and have one less thing to worry about.


That's probably not a great idea; the battery and the non-locking power connector were major design flaws with that model. When the battery stopped working, the camera would shut down abrubptly and unexpectedly when running from external power until I sent the camera in to get the battery replaced.

That's why the Ursa Mini bodies have locking power connectors; in other words BMD learned from that mistake and chose to not repeat it.
Rakesh Malik
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http://WinterLight.studio
System:
HP Spectre x360 Kaby Lake-R w/ 1080Ti eGPU in RazerCore
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Daniel Tufvesson

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Re: Remove internal battery? (BMCC)

PostThu Aug 09, 2018 11:51 am

So I went ahead and removed the battery and I can confirm that the BMCC runs fine without it. The battery indicator shows 100% all the time with no battery connected. For testing I formatted and filled up a 240GB SSD with both raw and compressed recordings.

Regarding the power connector I've run the Video Assist and the Pocket Camera without on board batteries for over a year now and I have not had a single unplanned loss of power. For me it's not an issue. I just use good quality 90 deg connectors of the correct dimensions and tie all cables down to the rigs.

To me this operation has been successful so far!
Feels better now knowing there is no longer a poor old Li-Po suffering under the hood.
Shoot - BMCC | BMPC | BMPCC | BMVA
Edit - Debian Linux 9 | Resolve Studio 15.2 | i7-3930K CPU | X79 MB | 32GB RAM | GTX1080 GPU | Decklink SDI
danieltufvesson.com/makeresolvedeb
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Rakesh Malik

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Re: Remove internal battery? (BMCC)

PostThu Aug 09, 2018 4:03 pm

Daniel Tufvesson wrote:Regarding the power connector I've run the Video Assist and the Pocket Camera without on board batteries for over a year now and I have not had a single unplanned loss of power. For me it's not an issue. I just use good quality 90 deg connectors of the correct dimensions and tie all cables down to the rigs.


I guess the tie down must be the secret. I just gave up and upgraded. :)

To me this operation has been successful so far!
Feels better now knowing there is no longer a poor old Li-Po suffering under the hood.


And there's a reason that BMD doesn't have a built-in battery in its later and much nicer cameras ;)
Rakesh Malik
Cinematographer, photographer, adventurer, martial artist
http://WinterLight.studio
System:
HP Spectre x360 Kaby Lake-R w/ 1080Ti eGPU in RazerCore

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