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4K & 6500 Watt Genny

Published : 21st July 2004


Hello.

Is powering a 4K HMI par from a 6500watt Honda genny a problem? What about a 5500watt genny? What about two 2500watt pars from either one of these genny's?

Thank you in advance for your advice.

David Jones
LA



Hello David,

One way to run a 4K off a Honda Put-Put 6500W generator is to run the 4K at 220V with an electronic ballast. This way you have all the generator's amps available since you are using both hot legs. Running it 220V will cut your amps in half too. Most of the regular Put-Puts have a 220V twist-lock connector. Connect the genny to the ballast with 4 pin twist-lock cable. You'll need an adaptor to connect it to the bates plug on the ballast. I think the retrofitted Put-Puts have 220V bates plugs built in. Not completely sure though. I've run 4Ks off 6500w Put-Puts with no problem. You should be able to run 2 2.5Ks on 120V on each hot leg. You might need bates to twist-lock adaptors though.

Alex Markle
L.A. based



>Is powering a 4K HMI par from a 6500watt Honda genny a problem? >What about a 5500watt genny? What about two 2500watt pars from >either one of these genny’s?

You can run a 4k on a 6500watt genny but you cant use the 5500 as it will not be able to start the 4K.

You should be able to run two 2.5K on the 6500watt so long as you don't turn both on at the same time just let one come up for a min before starting the other.

Keith Jakins
Australia



David :

The advice you received so far is good. I'd like to point out that it's all true insofar as the genny is in perfect condition. As with any other internal combustion engine a little drop in compression will translate in significant loss of power; besides engine cooling can also be a problem, a genny that runs everything OK for five minutes as tested in the rental facility could overheat after 20 minutes of running on the set (it happened to me). I wouldn't run any genny at more than 70% of its nominal output in any configuration.

Best of luck

Victor Lefelman



I have successfully used a 4k with a 6500 Honda Genny. One caveat though is that the genny was very new and in very good condition.

On another show I proposed doing the same thing, but the DP was doubtful that it would work...I assured him that I had done it before, so I rigged it up to test it and it would strike, but would not hold. In this case, the generator was actually the same model, but just judging from its exterior, it had seen a lot more battlefield time.

All I could extrapolate from those experiences is that with the 4K/6500w genny combination, you are apparently just about at the threshold of it working...so the condition of the generator is very important...the beat up one ran fine, and there were no problems with lower power units, but must not have been running at optimal efficiency.

The other lesson was, even when you know something will work...or should work...never test it out in front of the DP for the first time. Somewhere there is a DP who loved me for pulling off more than he expected could be done...then there is the other DP who probably thinks I am an ass and is still saying "I told him it wouldn't work."

If you're counting on being able to use these together, have them test the specific units you will be taking at the rental house, and don't just strike it... let the light burn for a good 15 minutes or so and make sure that it stays up and does not flicker or start having color shifts.

Sean Murray, soc
Camera Operator/Gaffer
Burbank, CA/Pittsburgh, PA



>I have successfully used a 4k with a 6500 Honda Genny.

My experience as well. It never hurts to ask the rental house that you have a good relationship with.

This is a question that undoubtedly comes up often for them. Not that you should put all your faith in the house but a good rental house will usually know from experience if THEIR 4K works with THEIR putt-putt.

They don't gain anything from sending you equipment that doesn't work or will only work if the Gods are all aligned.

John Roche, gaffer
NYC



David

A few years go I had this same question and the guys at Rosenthal Lighting 818 252-1010 here in LA fixed me up with a 5500W put-put and a 4Khmi with electronic ballast that worked beautifully together. They provided a wiring harness that made it work and I didn't bother getting into the details of how or why. I was sceptical because everyone else had said no. They hooked it up at their facility and assured me it worked before it was picked up by production. In theory a 5500W gene should power a 4K but of course since this is an HMI it isn't quite the same as hooking up 2 mighty's.

Of course it burned gas at the maximum rate so be sure to have plenty of fuel in reserve.

Randy "not an electrician but electricity makes my life easier" Miller,
DP in LA



So...the answer is..."trust the rental house and test the equipment".

Thanks everyone for your advice.

David Jones
DP LA



David Jones wrote :

>So...the answer is..."trust the rental house and test the equipment".

I've found the genny's designed for this in LA to be very reliable (although you gotta watch that gas gauge, I've gotten them with broken gas gauges reading "full" and NO GAS) but in other cities I've had problems with them. Even if you test them, sometimes they'll fire a 4K but then will only keep it on for twenty minutes or so (of course going out RIGHT as you're about to roll).

Best solution I've found is to bring along a 2.5K with your 4K just in case it doesn't hold the 4K.

Phil Badger,
Gaffer
http://home.earthlink.net/~badger111/index.html



Phil Badger wrote :

>Best solution I've found is to bring along a 2.5K with your 4K just in case >it doesn't hold the 4K.

This is sound advice...

I have used the twin cylinder 5500 hundreds of times on tracking vehicles. I consider that a 4k HMI is dicey even at 50 HZ with a magnetic ballast. It may strike and hold, or it may not.. at #60Hz the gene would be revving its little heart out. I would go for a larger gene if I definitely had to run a 4k..for any period.

Also electronic ballasts draw more current than magnetic ballasts nothing to do with being power factor corrected or not ...just they are a switch mode device using only 80% to 85% of the input sine wave, so input current needs to be higher.

Graham Rutherford
"Gaffers Always Know Best"
Australia



A couple of things to keep in mind about small genny’s: they have small fuel filters, so it doesn't take much crud to have a significant effect on performance. Carelessness in refuelling has led to a lot of unhappiness on the set. And these small genny’s need to be kept tuned for best performance. It is especially important to change the oil frequently -- not only to prolong engine life, which may not be a great concern to the renter, but to keep the compression high.

It is also important to keep the voltage adjusted properly. Here an accurate volt meter is essential.

Also, HMIs need to be properly maintained to minimize starting draw. Badly maintained units can draw a surprising amount of starting current -- way beyond the nominal wattage.

Brian Heller
IA 600 DP



David,

I agree with everything mentioned so far and have had both positive and negative experiences with this setup (4k on a 6500 Honda). The negative was actually due to too much voltage, oddly enough. I was using a fairly new and seemingly well maintained 6500 to juice a 4K when suddenly everything got very bright then dark.

After double checking and restriking everything, all was well for about an hour and then it happened again. We figured the 4K was drawing too much so I dropped the HMI and went with 2 2K mighty moles with dichroic filters. Sure enough, about 20 minutes after we were up and running again, the mighty’s suddenly ramped up and the globe in one failed.

After a lot of snooping around and metering (while waiting for the rental company to deliver a replacement) we discovered the throttle regulating solenoid liked to stick, causing the RPM's to soar and voltage with it. After asking around I found out that it is a fairly common problem when you are running these Genny’s at the top of their capabilities.

Just one more little issue to watch out for.

David C. Smith
LA/OC D.P
www.filmstox.com



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