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Running Arri 16SB on 9V?


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#1 Frederik Floor

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Posted 26 February 2010 - 08:39 AM

Hi

I recently bought an Arri 16SB with a Governor Controlled Motor (Constant 24fps) and a Variable speed 4-48fps motor, both running on 8V I think.
However, 8V batteries are impossible to find, at least here in Norway, so is it doable to run this camera and motor on a 9 or 7.2V battery over a long period of time without any tear?

And what amh does the camera need?

Thanks!

Frederik
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#2 Tim Carroll

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Posted 26 February 2010 - 09:53 AM

Frederik,

The Arriflex 16S/B, if it is properly tuned up, will draw 2.5 amps when running with a 100 ft internal load of film. When using the torque motor and the 400 ft magazine, the camera draws closer to 4 amps.

I have run an Arriflex 16S/B on two 7.2 volt battery packs wired in parellel when running with the 100 ft internal load of film. Works great, and you should be able to get half a dozen 100 ft rolls run through the camera at least before having to recharge the batteries.

Here's the ones I used, not sure if these are available in Norway or if you can possibly order them online.

Radio Shack 7.2 volt RC battery and charger

Best,
-Tim
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#3 Frederik Floor

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Posted 26 February 2010 - 04:27 PM

Frederik,

The Arriflex 16S/B, if it is properly tuned up, will draw 2.5 amps when running with a 100 ft internal load of film. When using the torque motor and the 400 ft magazine, the camera draws closer to 4 amps.

I have run an Arriflex 16S/B on two 7.2 volt battery packs wired in parellel when running with the 100 ft internal load of film. Works great, and you should be able to get half a dozen 100 ft rolls run through the camera at least before having to recharge the batteries.

Here's the ones I used, not sure if these are available in Norway or if you can possibly order them online.

Radio Shack 7.2 volt RC battery and charger

Best,
-Tim


Ok, that's great! But if I parallell wire two 7,2V batteries, won't that make them alot stronger, rather than only lasting longer?


Frederik
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#4 Tim Carroll

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Posted 26 February 2010 - 05:42 PM

Ok, that's great! But if I parallell wire two 7,2V batteries, won't that make them alot stronger, rather than only lasting longer?


Frederik


If you wire them in series, they become 14.4 volts, if you wire them in parallel, they remain 7.2 volts.

Best,
-Tim
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#5 Frederik Floor

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Posted 26 February 2010 - 06:04 PM

If you wire them in series, they become 14.4 volts, if you wire them in parallel, they remain 7.2 volts.

Best,
-Tim


Oh, thanks alot!
I found some 7,2V 1700amp batteries and I'll probably buy them very soon! Thanks alot for your quick replies!

Frederik
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#6 John Sprung

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Posted 26 February 2010 - 10:02 PM

The actual design Voltage is 8.4, so 9 should be well within tolerance, too. With the wild motor, you'd just be a little bit farther down on the rheostat, no danger at all.




-- J.S
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#7 Tim Carroll

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Posted 02 March 2010 - 03:16 PM

The actual design Voltage is 8.4, so 9 should be well within tolerance, too. With the wild motor, you'd just be a little bit farther down on the rheostat, no danger at all.
-- J.S


John,

You're correct as far as the wild motor goes, it will run off the 9.6 volt batteries with no problem. As far as the constant speed motor goes, that can be iffy. Some of the constant speed motors will be fine on 9.6 volts, but others will go "wild" and burn up. The newer ones, with the transistor on the side, will be fine on 9.6 volts. And I personally have an older one that takes 9.6 volts okay, but be aware, especially with some of the oldest ones, they can go "wild" which means speeding up really fast on the 9.6 volts, and if they do that for any length of time, they're fried.

If you have one of the constant speed motors, and a freshly charged 9.6 volt battery (when freshly charged they can run as high as 10 volts) you can turn it on for a couple of seconds, and if it runs smoothly and doesn't go "wild", you'll probably be okay. But if it does start to go "wild", shut it off right away and hopefully you won't have fried anything. Then get one of the 7.2 volt batteries, and that will run the motor okay.

Best,
-Tim
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#8 Frederik Floor

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Posted 05 March 2010 - 05:23 AM

Ok, so I've bought a 7,2V battery, and got a friend to do the wires right so it fits the camera, and when it is connected directly into the camera it runs smoothly at 24fps, but when it goes through a short 1m wire, it only runs at 23fps.

Does the wire have to be shorter, or what else could be the problem?

Thanks,
Fredrik
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#9 Tim Carroll

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Posted 05 March 2010 - 06:22 AM

Ok, so I've bought a 7,2V battery, and got a friend to do the wires right so it fits the camera, and when it is connected directly into the camera it runs smoothly at 24fps, but when it goes through a short 1m wire, it only runs at 23fps.

Does the wire have to be shorter, or what else could be the problem?

Thanks,
Fredrik


The wire could be adding more resistance, or it could be something else, without seeing your set up it's really hard to tell. Make sure the battery is holding a good charge. And if you wiring set up is already draining the battery, try the 9.6 volt battery option.

The battery packs I mentioned in the previous post were 2000 mah battery packs, and when you wire them in parallel, you have one 7.2 volt 4000 mah battery pack. I would doubt that a 1m wire would add so much resistance as to drain a 4000 mah pack.

Best,
-Tim
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#10 Frederik Floor

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Posted 05 March 2010 - 07:03 AM

Ok, I'll try to buy another battery..
The weird thing is, I tried to hook up my variable motor, and it ran at about 10fps when the cable was on it's way into the socket, but once completely in place, it doesn't run at all..

Btw, can I run 48fps on the 7,2V battery, or does it need more?


Frederik
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#11 Tim Carroll

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Posted 05 March 2010 - 07:28 AM

Ok, I'll try to buy another battery..
The weird thing is, I tried to hook up my variable motor, and it ran at about 10fps when the cable was on it's way into the socket, but once completely in place, it doesn't run at all..

Btw, can I run 48fps on the 7,2V battery, or does it need more?


Frederik


Sounds like your camera or your power cord needs to be looked at. The post sticking out of the camera where the plug inserts, are spring steel (or chrome plated brass) with a slit down the middle. Over time, that slit down the middle closes up and the posts become loose inside the power cable. That may be your problem. Or it could be inside the camera body where those posts go in. It sounds like you have a loose connection somewhere.

Running 48 fps will depend on what shape your camera is in, what shape the rubber motor coupling is in, what shape your variable speed motor is in, and having two fully charged 7.2 volt, 2000 mah batteries wired in parallel. If all those are in good order, and you fix the loose electrical connection, you should be able to run 48 fps.

Best,
-Tim
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#12 John Sprung

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Posted 05 March 2010 - 01:43 PM

It sounds like you have a loose connection somewhere.


Yup, it has to be bad contact. A meter of any reasonable size wire isn't going to produce significant voltage drop. More like a hundred meters is where you start thinking about it.

If you run for a while with that bad connection, you might start to feel a little heat where the problem is.




-- J.S.
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#13 Frederik Floor

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Posted 05 March 2010 - 05:21 PM

Yup, it has to be bad contact. A meter of any reasonable size wire isn't going to produce significant voltage drop. More like a hundred meters is where you start thinking about it.

If you run for a while with that bad connection, you might start to feel a little heat where the problem is.
-- J.S.


I've tried it a bit more, and it starts out fine at 24fps, but drops to about 12fps over a minute or so. I haven't got a charger yet, but I'll fix it and hope that it might help.
Otherwise; We connected the battery into the camera directly and it worked fine, so I'm at least glad the bad connection won't be inside the camera, if there is one at all.

I'm gonna make the charger of a 220V transformer, which transforms to 7,5, 9 and 12V. Which would work best in charging the 7,2V battery? I'm guessing the 12V is to powerful.

Thanks alot for your help!
- Frederik
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#14 Tim Carroll

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Posted 05 March 2010 - 05:47 PM

I'm gonna make the charger of a 220V transformer, which transforms to 7,5, 9 and 12V. Which would work best in charging the 7,2V battery? I'm guessing the 12V is to powerful.


That's beyond me, I don't know squat about electricity.

Best,
-Tim
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#15 Ed Sieb

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Posted 07 March 2010 - 09:16 AM

[...] I'm gonna make the charger of a 220V transformer, which transforms to 7,5, 9 and 12V. Which would work best in charging the 7,2V battery? I'm guessing the 12V is to powerful.


OK - I assuume you are somewhere in Europe, what with a 220 VAC mains?
Remember that you need DC for the camera. Make sure you get good guidance from an electronics tech to guide you. You will need a mains transformer, rectifier, capacitors and regulators to derive the voltages you want. In any case, 12 VDC is to much for the Arri motors. I believe I provided a circuiit to regulate 8 VDC from 12 volts, in another thread.

As far as your voltage drop is concerned, make sure that you use a large enough size of wire to feed DC to the camera. Here in North America, we would use no less than #14 guage wire for the battery to camera conection, 1 meter or less. For a meter (approx 39 inches) or more I would use #12 guage wire. The Arri's draw at least 2.5 Amperes, and that will cause a significant voltage drop in thin wire. I'm sorry, but I have no idea of European wire guages :unsure: or what their equivalents would be.
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#16 Oliver Christoph Kochs

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Posted 07 March 2010 - 04:15 PM

Just a short notice based on my experiences.
The motor from the S doesn't work with NiCads or NiMH cells. The amperage needed will drain these too fast.
What you need is a lead acid cell. These supply the power that the motor needs. Back in th days you could just grab the 12V battery from your (t)rusty volkswagen and shoot with that.
I have always used 12V batteries without problems. The motors (IC type and rheostat) can handle 12V - they can become warm and then you just need to wait for a minute.
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#17 Tim Carroll

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Posted 07 March 2010 - 04:41 PM

Just a short notice based on my experiences.
The motor from the S doesn't work with NiCads or NiMH cells. The amperage needed will drain these too fast.
What you need is a lead acid cell. These supply the power that the motor needs. Back in th days you could just grab the 12V battery from your (t)rusty volkswagen and shoot with that.
I have always used 12V batteries without problems. The motors (IC type and rheostat) can handle 12V - they can become warm and then you just need to wait for a minute.


Oliver,

Couldn't disagree with you more. I've been running an Arriflex 16S with 100 ft. internal loads on the battery packs I linked to above for years and never had a problem. They're NiCads. I recently started using 9.6 volt NiMH battery packs for the Arriflex 16S and they work equally as well.

You need to make sure your battery packs are high enough in their mah ratings (milli-amp hour ratings). The 9.6 volt packs are 1600 mah, and the 7.2 volt packs are 2000 mah (which I team up in parallel, which makes them 4000 mah), and they all work fine. If I wanted to run the 400 ft. mags with the camera, which I don't do, I would team up two of the 9.6 volt batteries which would give me a pack with a 3200 mah rating.

Best,
-Tim
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#18 John Sprung

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Posted 07 March 2010 - 09:20 PM

Tim has it right. It's the battery's capacity rather than its chemistry that matters. The rule of thumb is the ten hour rate. You want to draw from a battery no more current than it's rated to supply in ten hours. From a 3200 mAH battery, the ten hour limit would be 320 mA. Of course, for film cameras, we routinely push well beyond that, and pay for it with reduced battery life. Push way too far, like around a one hour rate, and the poor battery might not even be able to turn the motor at all.

Commonly available lead acid batteries are made for things like UPS's or motorcycles, so they generally have more capacity than the Ni-Cad's and NiMH's that are made for smaller applications.





-- J.S.
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#19 Oliver Christoph Kochs

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Posted 08 March 2010 - 05:23 PM

Tim and John, thanx for the info with the NiCad or NiMH cells. It obviously works when multiple packs have been wired parallel to get to 4 AH. I have used only one pack wired from ten 1,2 Volt AA cells with 2000mAh in a row. That obviously wasn't enough so i went with the lead acid battery instead and it worked for me.
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#20 Frederik Floor

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Posted 16 March 2010 - 03:32 PM

Ok, so I got another 7,2V battery today, and got help parallell wiring these two completely similar batteries. So thats plus on plus, and minus on minus, using a three pin XLR with one pin left over..

We tested it in the voltage meter and it showed around 6,3V, however not steady at all. And nothing happens at all when I plug it into the camera. It worked a little with one battery, but not at all with two of them. We've also checked all connections and they're all in shape, no bad contacts.
What could possibly be the problem?

Thanks for your help!
-Frederik
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