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Li-ions and the 435


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#1 Stephen Murphy

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Posted 26 November 2004 - 12:21 PM

A while back i learned a little tidbit i thought some of you might be interested in.

I had a commercial about a month or so ago, which was to be shot at high speed on a 435. During the prep day i found that my sled,running 3 pag lithium ions, wouldnt start the 435 even at 24 fps! This wasnt the first time i had flown a 435 and i hadnt had any previous problems so this caused me some confusion.
This was however the first time i had flown a 435 from Panavision, and this was a 435 ES, not an advanced or an Xtreme. After much disscussion with Howard and the PV technicians we managed to figure out that the Original 435 and the 435 Es both have an 18 amp spike upon start up (the newer 435's have a slow ramp option to deal with this) and the Li-ion batteries couldnt deal with this brief spike. The simple solution was to switch out one of my li-ion batts to a 50w nicad batt and that solved the problem. The nicad battery took care of the power spike and the lithium ions ran the camera all day at 75 and 100fps, I didnt need to change batteries for the entire day (which was all steadicam). So the moral of the story is always go to the prep and never hire a 435 from Panavision:)
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#2 Benjamin Treplin

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Posted 26 November 2004 - 01:44 PM

Hi Stephen,
a friend also use PAG Li-Ion an NiCad Batteries on his sled.
He ran into some problems combining NiCad and Li-Ion chemistry. It caused the Li-Ion (L-75) to shut down and refuse operating until it had spent some time on the charger. I'm surprised that nothing similar happened. Do you use the L-95? What's you maximum speed on the 435 with your batteries?
Best
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#3 Stephen Murphy

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Posted 26 November 2004 - 02:43 PM

Hi Benjamin,

I didnt have any chemistry problems at all. Im using the Pag L-75's (lith-ion) and the new Pag Lok-on 20's (nicad) on an Mk-V evolution sled. I ran the camera at 120 fps with no problems for a whole day on the same set of batteries- i didnt test it at 150fps. Hope this helps.
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#4 Rudy Katkic

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Posted 26 November 2004 - 10:06 PM

Hi,

FYI, outside of flying the 435 on a rig, plugging it into an especially long extention power cord i.e. camera is on top of a 10 foot ladder and battery is down on the ground, the camera will also not be able to run properly as a result of its very specific voltage needs.

Found that one out the hard way.

Cheers,

Rudy
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#5 Benjamin Treplin

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Posted 27 November 2004 - 04:10 AM

Hi Stephen,
thank you for the information. I will forward this information and maybe we'll run some tests.
Hi Rudy,
this is an interesting issue. You will run into this situation on every crane setup. Every cord has an internal resistance and as result a voltage drop. On a long extension cord it is possible to have a voltage drop up to 2V. With a 24V battery the camera will not run. If my memory serves me right the 435 needs 22V to run at all and at least 25V to run high speed up to 150 fps. A lot of sleds are equipped with to small wire gauge sizes, the in post cord is coiled and the connectors are a bit to small as well. As a result the system has high resistance / voltage drop. Maybe the batteries alone can handle the camera but not in combination with a steadicam setup. Hope this makes sense.
Stephen is right, always do a prep.
BTW Stephen do you have a pic of the lok-on 20 NiCad? There is nothing on the PAG website.
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#6 Stephen Murphy

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Posted 27 November 2004 - 04:59 AM

BTW Stephen do you have a pic of the lok-on 20 NiCad? There is nothing on the PAG website.
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<{POST_SNAPBACK}>


Hi Benjamin,

I dont have a photo handy but i can take one on set next week and email it to you. Pag originally made them for the chrosiel rig: Howard smith got to play with them at a trade show and recommended them to me. They are about the same size as an L75 but twice as deep and heavier. This extra weight helps me on heavier cameras like the 435 as i like to keep a short post and work with a quick drop time. I think they were around Euro 300 each.

While scanning through the old AOL folders i found another tip about powering the 435: At the back of the camera, under the magazine port, there is a small black button which gets depressed when the camera is fitted with an older Arri 3 magazine or a 1000ft 435 mag. When depressed this button apparantly reduces the massive power spike which can be too much for the older magazines to take. It was suggessted that if you tape this button down when using a steadimag or regular 400ft (in studio mode) it might help your batteries run the camera.

I havent tried this myself. Nice tip though and yet another reason why it would be great to have the AOL folders archived for all to see.
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#7 guillermo nespolo

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Posted 27 November 2004 - 12:02 PM

hi i just finish a work witha 435 with my mk-v and 3 aton buer proformer 14,4 and 30w and i shoot about 5 mags at 50 and no problem , yes in the few years before i try to run a 434 with 2 proformers ...hahahah keep on trying baby ...the arri guys and howard tolme about the start of the 435 and besides ...i have to change the ramp just because when u start the camera tilts up like crazy......with out a ramp...


i hope i get soon my hands on the new 235 that a rental house buy already
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#8 Brad Hruboska

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Posted 27 November 2004 - 05:15 PM

Yeah Ihad a weird situation with the Arri 3 and the Li-ion batteries this week, which I attributed to the cold weather we were shooting in. It would start up ok, and then one breaker would soft trip on the sled ( pro 2 ) , switching to the profpormer Nicads solved the problem. I agree, I have to keep a couple of Trimpacks for the older 435's just to deal with the amperage spike. We had problems way back when they were introduced with remote heads too, too much resistance in a line to pass the amperage....great camera, but power hungry to be sure.....

:huh:
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#9 sebastian matthias

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Posted 28 November 2004 - 02:59 AM

hey everybody !
this might be a stupid question,but do li-ion batteries allways have a lower output than Ni-Ca Batteries ? i was thinking about getting li-ions but now i´m not so sure anymore.i use the anton bauer trimpacs and never had any problems.i actually lew a 435 at 150fs with them on a commercial and it worked fine.(it was a ramp from about 50fs to 150 fs !).schould i stick with my Ni-Ca s or what is the real advantage of Li-Ions?(beide the weight?)

all the best

sebastian
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#10 Benjamin Treplin

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Posted 28 November 2004 - 05:24 AM

Hi Sebastian,
A few months ago I had the opportunity to test swit Li-Ion batteries with a 435. The German dealer lent me two 126Wh batts. Fully charged it was no problem to get to 150 fps, I rehearsed the start up about 10 time for a duration of 10 seconds. I had no stock to test the 435 with so I blocked the takeup core with one hand. The highest power demand is between 120 and 150 fps. The Voltage dropped from 32V to 25V during acceleration. Just before the 435 reached 150 fps it dropped to 25V, on speed it reached 28 to 28.5V again. Unfortunately I didn't have enough time to discharge the batteries and test them at 70% or 50%. But for me this was enough proof. IMHO these batteries can handle most situations we encounter.
Last week I got my new Li-Ion batteries from swit and they rock. I have two sizes 88Wh and 126Wh with A/B mount. One 126Wh battery last two days of shooting and powered my green screen monitor, modulus, miniDV onboard recorder and BFD. In addition the batteries are not so wide as the Trimpacs are.

I agree, I have to keep a couple of Trimpacks for the older 435's just to deal with the amperage spike

I second that. Li-Ion chemistry has a higher internal resistance. If I'm right twice Ni-Ca has. This causes a higher voltage drop under load and therefor a higher amperage. A small set of Ni-Ca batteries is always useful.
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#11 RobinThwaites

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Posted 29 November 2004 - 05:26 AM

Hi Stephen

FYI the PAG L-95 will cut out at around 5 amps whereas NiCads will run much higher currents. One thing you can do is parallel wire Lithiums which is something you should NEVER do with other chemistry batteries. Also, Lithiums should not be affected by the cold whereas NiCads will.

Strange that Arri had the start-up spike problem on 535s and cured it and then built the earlier 435s without addressing the problem.

Robin Thwaites
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#12 Benjamin Treplin

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Posted 29 November 2004 - 05:52 AM

Robin,
why not parallel Ni-Ca and Ni-MH? The PAG "power modul"/"power plate" is doing this or am I wrong? Or did I misunderstood this completely?
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#13 RobVanGelder

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Posted 29 November 2004 - 12:56 PM

You can use them parallel, NiCd or NMHi, but it is best to use diodes between them or they will start "balancing" on each other. That means that if one is a bit higher in voltage it will discharge into the other when there are no diodes.

The problem with the diodes is that you have to find the right ones that can handle the current and a second effect is that you will loose about 0,6 to 0,9 volt per battery.

I found some here but I am not really happy with that voltage drop so I am looking for another solution.

Phil Rhodes? are you still reading this forum?
:huh:
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#14 charlesneufeld

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Posted 29 November 2004 - 09:55 PM

Hey Rob and Guys,

You should look at these two diodes I have found, and work well with my Parallel NiCad setup.

They are both Schottky Power Diodes which have a lower Forward voltage drop than other diodes.

International Rectifier 20CTQ... series (20A 35-45volts)
or onsemi MBR2030CTL (20A 30Volts)

Both have a drop of about 0.5v but they are both in TO-220 packages so a little bigger than the inline <_<

I have the datasheets on both if you want me to send them to you.

Charles :)




I found some here but I am not really happy with that voltage drop so I am looking for another solution.

<{POST_SNAPBACK}>


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#15 RobinThwaites

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Posted 30 November 2004 - 04:56 AM

Hi Benjamin

Sorry I should have specified "without other electronics", basically one battery will try to take charge from the other.

Robin Thwaites
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