Blackmagic Forum

I've been looking around but either haven't found the right search term or it's just not a thing, but I'm wondering if anyone makes a two battery plate or shark fin that could take two 14v batteries and connect them in series to power higher voltage cameras. Everything seems to be in parallel, which makes sense for using with the same voltage camera, but it sure would be nice to be able to use my stack of flight-safe v-mounts with an Ursa Cine. Obviously you wouldn't be able to hot swap but it seems electrically possible. Like, Aputure makes a dual v-mount 48v battery box for their lights, why not a dual v-mount to 28v b-mount shark fin?

Is this something anyone has seen?

I'm very interested in an Ursa Cine, especially with the new body only version, but batteries are a conundrum. 98wh batteries in b-mount cost nearly the same as bigger 275wh batteries. I think for non-flight shoots I'd want 275wh batteries, but then I'd need a grip of 98 wh batteries for air travel that cost just as much. With the 12k OLPF I usually fly with 8-10 98wh v-mounts and I'm assuming I'd need even more with the higher draw of the Ursa Cine and that's a whole lot of money on batteries.

Edit to add:

Blueshape has a voltage step up adapter that's very expensive. It's gotta be too much draw for a normal singl v-mount but maybe combined with a shark fin could work? https://www.adorama.com/bsmv2bm.html

I have a switronix v-lock sharkfin that would be really easy to rewired for a series configuration. However, I would be worried about it accidentally getting used on a 12V camera. Without some very visible warning, there could be a very costly mistake on set.

Yeah, ideally it'd be like... the battery side has v-mount and the camera side b-mount to avoid that issue.

I do have a Sony NP dummy battery with unregulated d-tap connection that I'm sure would not be good for a camera expecting half the voltage.

Just speculating here. You can double batteries in series but it's not really ideal. You are correct from what I can see, the 24v b-mount batteries appear to be just double 14.4v v-mount battery voltage.

However, if your batteries in series are mismatched in either capacity or charge you will be limited by your lower capacity/charge battery potentially depleteing it below it's recommended voltage per cell.

Ie good battery is 4v per cell and sad battery is 3.6v per cell and these are 2x 4 cell batteries the camera will think the
(1x) 8 cell attery is fine at 3.8v average per cell but said sad battery is going go under pretty soon because it's already near exhausted.

Mm, that's a good point. The V-mounts I use say they have over-discharge protection, wouldn't that just shut down the sad battery in your example? Obviously you're still limited by your least charged/good battery, but that would be a decent tradeoff I think.

Jon Hustead wrote:Yeah, ideally it'd be like... the battery side has v-mount and the camera side b-mount to avoid that issue.

Ideally? 24V on a V-Mount is a poor idea, if not outright dangerous. I would hazard a guess that the 24V plates and the 12V plates use different pins in the Molex connector. If it's not then the circuitry needs to be complex enough to protect both 12V and 24V sources. Given that level of complexity the cam may never go into 24V mode from a V-Lock.

dolby1970 wrote:I have a switronix v-lock sharkfin that would be really easy to rewired for a series configuration.

I want to see the vid when you try it for the first time, actually please don't, seriously.

Good Luck

There are already battery manufacturers that make dual voltage v-mount batteries that have some kind of communication to ramp up into 28v mode, so they could presumably make a shark fin that does the same thing. There's a thread somewhere on here that the Ursa Cine v-mount plate does work with CoreSWX's versions of the same. "Ideally" my batteries in series shark find would also have with some circuitry to balance the battery load and offer regulated 14v d-taps.

My main question remains if someone already makes something like this — it seems very doable electrically and you could do it in a way that's camera safe, I think it's just a matter if there's enough market for anyone to actually make one.

You can make batteries. It's fun if you know how and have a few essential tools and testing equipment (spot welder, IR meter) and a little bit of skill and knowledge along with good quality parts (Japanese cells and a good BMS with thermal cutoff). 16 cells (8s2p).. You will need to go 2p or 3p at least to supply over 150W reliably for a reasonable amount of time, at a complete guess..

But the biggest issue with a camera is probably the ergonomics. You will want a really good connector and some kind of housing and you will want it integrated. And it will need to be rock solid.