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Will Jacobs

Power an ARRI SR I/II with 14.8v Batteries?

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Is it possible to power an ARRI SR I/II with 14.8v gold mount batteries? I understand the voltage would need to be converted to a regulated 12v, but even then is it posing a risk? I happened upon this plate:

https://www.bhphotovideo.com/c/product/839205-REG/Movecam_MOV_306_0208_BATTERY_BRACKET_FOR_GOLD.html

I would have to use a 3-pin male LEMO to 4-pin XLR cable to take advantage of the regulated 12v output. Is that possible, or would it pose problems?

Any insight would be dearly appreciated, as I'm quite uneducated when it comes to power supplies. Thank you!

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Apart from a few issues listed in the customer reviews, like noise from the voltage converter (not great with a sync sound camera) or poor lock-offs, I don’t see why that wouldn’t work. You’d probably want to check out how noisy the thing really is if you wanted to do sync sound work.

SRs don’t pull that much current, so the Lemo connector should be fine. I don’t know if you’ll find an off the shelf cable, but you could always have a custom cable made.

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Dom,

I did take note of the reviews. As silly as it sounds, I wonder if I could make a custom barney with a small acrylic window to slip around the plate and battery if the noise is a nuisance. 

Another review states, "The 3-pin 12v Lemos are not the Arricam 3-pin size. The ones marked 12 volt are one size to big." I wasn't aware of the varied sizes of 3-pin Lemo's. Which one would be proper?

As for the Lemo connector, is there a particular company you would recommend for making the cable? 

Thank you very much for your knowledge and guidance! 

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Lemo have about 5 different size connector series, maybe more! 

That cable looks about right, but you’d really want to contact the sellers or manufacturers to make sure. The plugs look right in terms of gender (power out is always female, power in male), and that looks the right size Lemo. 

You’d also need to check that the wiring is right. 4 pin XLRs for 12V are fairly standardised at pin 1 ground, pin 4 +12V. The 3 pin Lemo wiring you’d need to check that both the adapter and the cable specs match. An electrical tech could easily check and change it if necessary.

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The listing doesn't mention that is has a 12v regulated output.. it could just be transmitting the battery voltage straight through, which is a little high for a 12V appliance like an SR. I'd check with the seller. Looks home-made..

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Dom,

I purchased a MOVCAM battery converter which apparently had a regulated 12v XLR output. After ordering a 12v cable and a F-to-F NEMAL adapter, I measured the voltage with my multimeter and was disappointed...

Could this be true? Clearly it is, as I measured the 12v LEMO outputs which gave me readings of around 12v. The supposed 12v D-Tap outputs measured 16.60v along with the 14.8v camera output.

I'm now perplexed. 

 

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2020-03-19 13.39.52-min-min.jpg

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Well if it’s not giving you what the specs and the advertising claim, contact the seller or manufacturer. Maybe you got a faulty one?

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I contacted CORE detailing my situation and this was their response:

"The product is stated to be a 14.8 volt battery.  That is it’s plateau voltage,  meaning where it voltage stays the longest.   All 14v batteries charge to 16.6 to 16.8 volts.

All professional accessories will handle the voltage.  The voltage you are seeing is called skim voltage and will drop as soon as you turn on the camera."

I also opened the Movcam converter, having purchased it off of eBay and no need to return it, discovering that the XLR does not go through any down-conversion or regulation:

 

2.jpg

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Yes the battery voltage behaviour is normal, though whether older 12V appliances are all capable of handling over 16V is not a given. The fully charged voltage will drop under load, but not by much, which is why you got a regulated 12V converter in the first place, right?

So your issue is with the Movcam product - specifically if the 12V XLR output or D-taps were advertised as regulated. Clearly they’re not, so you have a case for complaint. You could use a custom cable to plug into the regulated Lemo outputs, but presumably you bought this Movcam product to avoid that and just use a standard XLR cable. I guess if you can’t get a refund, you (or an electrical tech) could just internally rewire the XLR socket to a Lemo output, but you’ll void any warranty, if it came with one.

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OR there may be enough space inside the box to add your own separate regulator just for the XLR. depending on how much current you are going to draw from it.

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