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Only You Can Prevent Movi Fires

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When you run a rental house, you basically function as a torture-test lab for equipment. For many years I've put out a Repair Data list annually, showing which photography equipment is more likely to fail than others. I get asked to do the same thing for video equipment, but I usually just shrug and say it's not necessary. I can sum it up simply.

If the product is new and exciting it will probably fail.

If the company is new and cutting-edge, the product will probably fail.

This sounds like a generalization, and it is. It also sounds like an exaggeration, and it's not. New, cutting-edge video equipment from new, cutting-edge companies has an extremely high failure rate. For a lot of these products, nearly 100% fail within a few months.

I'm sure some of you are thinking I'm just being overly harsh about cutting-edge products from new, cutting-edge companies. Really, I'm not. I'm just using common sense. Think about it. Some guys come up with an idea for something great and unique. They might convince an investor to back them, or maybe crowd-source some funding. They put together a prototype, find a parts suppliers, and assemble maybe 5,000 of that item. They might even budget to get Famous Cinematographer Guy to use it and blog about it.

You know what they don't budget for, because it's really expensive? An engineering firm to do failure testing and find out where the electronic and mechanical weak points are. So they release the product, it starts breaking, and guess what? They spent all their money to make 5,000 new widgets. They don't have any spare parts for repairs. For that matter, they probably don't have a repair department.

The truth is, I totally understand it. I meet a lot of young entrepreneurs who are trying to bring exciting new products to market. They truly mean well, and they truly believe in their product. They're desperately trying to get their new product to market. That's such a huge task that it's hard to worry about customer support until later.

Lensrentals Mods

We generally don't make a big fuss about this kind of thing. If you hang out on Lensrentals.com you might see some exciting new products disappear after a few months. That's what happens when we realize there's no way to keep a product operating long enough for most renters to use it.

More commonly, you might find a product you rent has been modified a bit. We do this when we think a product has great potential except for the fact it breaks frequently. Since we've got a repair department full of gear-heads who like trying to solve these kinds of problems, that seems the logical way to go.

The Edelkrone Sliders are a good case in point. It's a brilliant concept, a smoothly moving slider that extends as it slides, so a 17-inch slider slides a full 24 inches. Unfortunately, the cheap belts sent out with the first ones had a problem: they permanently bent in the 'rest' position, so when you slid you got a big bump every time the belt passed the bend.

We replaced the belt with some top-of-the-line automotive timing belts and it worked better. Edelkrone replaced it with some soft nylon cord. That worked well, too, except that it the soft cord broke frequently. We've been pleased to see they finally have started using the same belts we've been using for months (we do like to be right). We've also replaced the feet that have little stuck-on rubber pads that come off, and tried several fixes for the plastic bearings that fall out and get lost when the belt breaks or comes loose. It's a great concept, but we'll probably wave the white flag and discontinue it soon.

Red Rock's One Man Crew is a similar, if more complex, product. Amazingly good idea, but it's hard to keep in service. But it's so cool we've tried. We've glued foam inside to reduce the rattling. Aaron even tried replacing the soft plastic gear teeth that wear out in amazingly short time with wooden ones (epic fail) and metal ones. We love it. We hate it. We'll keep trying fixes for a while to see if we can get it reliable enough to keep renting.

Now don't get me wrong. You should certainly have fewer problems than we do. For one thing, you've probably spent some time reading the instructions before you started using your expensive new purchase. Renters don't do that, probably exceed weight restrictions, and do lots of other things you wouldn't do with your own equipment. So just because something has problems under harsh rental conditions doesn't mean it will have problems when you baby it. But remember, too, that most of the equipment we carry, used under those same harsh conditions, hardly ever fails.

Don't Cross the Streams

Once in a great while, though, we come across something that's actually dangerous and feel like we need to tell you about it - both for your possible protection and to explain why something you rent from us looks rather odd.

The Freefly Movi is in that category, unfortunately. The product is so great that we did a workaround that should keep it safe. It's not pretty or professional, but until we come up with something better it will have to do. If you own one, I'd recommend you do something similar, unless you're one of those people who actually follow directions meticulously and always makes sure anyone who uses your equipment does too.

The battery system for the Movi is a LiPo system that, like the Movi controller, is borrowed from the Radio Controlled Model industry. There's nothing wrong with that. Unfortunately, though, the charging cords are a fairly narrow gauge, and more importantly, the ends of the charging cable are free to touch each other when the cable isn't plugged into the charger. Since the battery cable connector can be a bit difficult to release, a lot of people leave this cable connected to the battery.

Freely Movi charging cables. As the website shows, you shouldn't leave these cables plugged into the battery and then let the copper tips touch. Image http://store.freeflysystems.com/products/replacement-leads-for-movi-battery-charger

 

Now I'm not an electrical engineer, but even I know when you let the positive and negative terminals of a powerful battery come in contact with each other the battery discharges fast. Which gets hot. How hot? Start a fire hot. We've had 3 fires now, all started when a renter left the charging cables plugged into the battery, but not into the charger, so that the copper tips of the charging cable could touch each other. Like this.

Like Murphy's No Smoking Rule says: No electronic component will work properly unless all of the smoke is kept therein.

 

This isn't particularly Freefly's fault. They clearly tell everyone to be careful, to not leave the battery plugged in to the cable unless the cable is inserted in the charger, etc. Plus, we sort of assume everyone knows that basic rule of electricity and ghostbusting: Don't cross the streams.

But in the rental world, at least, a lot of people are no more likely to read the directions than I am. Third-assistant grips hired for the day don't ever read directions, for example, and they're usually the ones packing up the equipment.

Our fix isn't elegant, but it should be effective. We just mold a plastic piece out of Sugru that keeps the terminals from touching whether they're plugged into the charger or not. We'll eventually find a supplier with a nice, thick-cabled, fixed-plug JST charge lead and replace our homemade fixes with that. But for now, if you notice a homemade plug on the battery charger, you know why.

If you have a Freefly Movi and you're a careful person, you're probably fine. But if anyone else uses it that doesn't know better, we strongly suggest take a few minutes to make a similar solution. You don't want to be the guy whose luggage starts burning halfway through the flight. If you don't like Sugru, you can get a fixed space banana clip plug but make certain you clearly mark positive and negative terminals or other bad things might happen.

OK, the blue color is kind of a fail, but you get the idea.

 

I'm not just slamming the manufacturer, here, I'm slamming myself, too. Like every other product that we rent, I examined it when we first began stocking it, looking for weak points so I could go ahead and order repair parts, etc. I never thought of this problem until after it happened. Actually, the first time it happened we assumed there must have been some kind of short in the battery. Only after the second fire did we realize what the actual issue was, and there was a third before we put some corrective measures in place.

We all need to remember just how powerful today's batteries are. Discharge all that power too fast and bad things happen. Making a direct connection between the positive and negative poles of a powerful battery is like pulling the pin on a grenade. Like the military saying goes, "Once the pin is pulled, Mr. Grenade is not our friend."

The military have another saying I like: "Remember, every part was made by the lowest bidder." When you buy that new, exciting, cutting-edge piece of equipment, that's completely true.

 

Roger Cicala

Lensrentals.com

June, 2014

 

 

23 Responses to “Only You Can Prevent Movi Fires”

Aaron said:

As soon as I saw the image of that plug connector, given the direction you were going, I knew it would end up with someone having packed it up still attached and nearly caused an lithium battery explosion.

Brian Churchwell said:

Adding an inline fuse would be safer, but how many extra fuses would you include in a rental?

Nqina Dlamini said:

While reading this, I couldn't help but wonder if your insurance company is also reading it. And Getting themselves a sort of "you admitted to be reckless in your blog so no payout for you" idea...LOL

Larry said:

You really should put a fuse on that wire and a big warning label to unplug from the battery. If the two ends contact a metal piece you are back to the same issue. And the manufacturer should issue a recall.

Will Frostmill said:

Geez, there are interconnects especially designed to prevent this problem!
I like Anderson Powerpole connectors. (Link here: http://www.andersonpower.com/products/singlepole-connectors.html ). All kinds of industries use them, but they latch, they are polarized, they can be stacked, they come color-coded, and above all, they are touch-safe!

I would recommend completely replacing the existing plugs with these right away! Just glue in the existing plugs and put some powerpoles in the middle, or better yet, replace the wiring and sockets all together. And then badger the manufacturer to do the same! They come in all sizes and capacities, up to 350 amps.

(Model railroading guys use them for modular setups like Ntrak. There's actually a written standard...)

Rupert said:

I notice the sugru covers the red and black pastic of the plugs, I can see someone plugging them in with the polarity reversed. . . . Fire when charging = BIG fire.

LensRentals Employee

Roger Cicala said:

Rupert, we've carved it back to make sure the plug color shows, but we're probably going to change over to rewiring the whole assembly. This is a bit of a stop-gap until we figure out the best way to do that. Truth is between this and already a dozen dead batteries because people run them dry (once that happens they're dead forever) we're really looking at replacing the entire battery-charger assembly.

Michael R. said:

The better way would be using better plugs. The first thing that came into my mind was to use these: http://www.sks-kontakt.de/index.php?page=shop.browse&option=com_virtuemart&Itemid=101 These don't require changes of "the other end". And theoretically exchange one plug would prevent shortcuts; still both would be better.
If it's possible to change the other end a connector preventing wrong polarity would be much better.

Michael R. said:

Argh. Sorry I noticed that the link in the post above did not point to the items I was looking for. Search for "SLS 200" on that page. And another assumption was that the connectors are 4mm plugs.

Gert F Hansen said:

An alternative low-tech "solution" is to make one of the cords ½-1 inch shorter than the other; It looks a little funny when plugged in but it works.

This works well for speaker cables too (at the speaker end) and I believe it has saved more than one power amp for me, when in the heat of speaker comparisons someone (tm) forgot to turn off the amp before unplugging the cables at the speaker.

A said:

I must admit Brian suggested a fuse, I was thinking gunpowder, rather than 2A inline ;)

Cool job, finding and fixing problems before they happen though - that sounds like my kind of gig!

Scott said:

The RC hobby has already pretty much figured this out. The lipo battery leads are typically taken to a female type connector to make it harder to short out the battery when disconnected from a vehicle or charger.

Also, the Lipo cells need to be kept above 3.0v per cell. discharging then beyond that can end in a fire as well. Most RC vehicles will have a lipo cutoff circuit to prevent this.

Not sure how many cells the freefly battery has, but if it's more than one, they should be charged with a balance charger to make sure that no individual cell is charged more than 4.2v per cell.

Finally, lipo's should be charged and stored in firesafe bags or containers.

Dr Croubie said:

I would also recommend to the manufacturer to change the plugs to something less likely to touch, even the same as on the other end to plug into the charger would help. A reverse-polarity-protection diode somewhere in there will also prevent current flow if the two ends do still touch. Another option is that I've actually got a model helicopter where the cable is fixed to the charger, only one plug on the heli, and it won't take off with it plugged in.

But if 10 years as both electronic and electrical design engineer has taught me anything, it's my favourite saying: "if you make anything idiot-proof, god will make a better idiot"

Matthias Welwarsky said:

I'm a bit shocked finding a bare LiPo battery being used without proper protection circuitry. I used to work in consumer electronics and I know that there are regulations for that. All devices we made had a small PCB attached to the battery with an integrated protection circuit that cut the connection as soon as the wires were shorted. Believe me we didn't do this for fun since it added to the bill of materials, but because we had to for compliance with regulation. Even though the battery was not user-servicable and inside the device case where it could not be touched.

Lynn Allan said:

This article makes a good case for "rent before buying" on latest/greatest stuff. I think that might especially apply to something like the Samyang Tilt/Shift ... rent the lens to try it out. The build quality doesn't necessarily inspire confidence. Or not?

Hmmmm ... an interesting, recurring article might be "lens, cameras, and non-lens stuff LR no longer carries because it wasn't built well enough to rent".

NormSchulttze said:

You need to talk to your local FSDO. I wouldn't what that product in the cargo hold of my aircraft. Aircrafts have been lost due to fires from high power batteries.

NancyP said:

Roger's rule concerning new product or new feature failure is likely the reason why the pro cameras generally do not carry new technology, just a better grade of old technology. Note that Canon introduced the dual-pixel autofocus technology on a consumer model in a line that refreshes fairly frequently.

John Leslie said:

NancyP - strictly they put the hardware in a three very Pro cameras first (C100, C300 and C500), they just "trialled" the firmware in the 70D before allowing Cx00 users to upgrade to it. Plus unlike small companies they would have had cameras in trials for many months prior to release.

Nicos said:

As an aside, those spaced plugs may not be readily available in countries using "Euro" or German mains plugs. Since the spacing is rather compatible and those plugs used to be on loudspeakers, there were some loud incidents (think 4 kilowatt *WRRRRRBOOOM* followed by a huge bass magnet forcefully leaving a smoking speaker enclosure), which led to those parts falling out of grace and off the market.

I would, however, generally speak out against the use of RC electrics. Those are about the worst you can get. Sure, they're readily available, but most plug systems suck noodle; this one also uses a BEC connector which is relatively robust and more importantly has crimp contacts on the battery, but overall that market is full of hogwash. There are a couple of good, locking, and yet easily separated interconnevcts on the market, and yet they are not used in RC, in favour of cheap hack solutions. If you've ever tried to solder a flimsy barrel connector onto the massive lead of a battery pack, with the other lead tied to the pack with half a roll of tape to avoid it snapping loose and welding itself to your vice, you know what I'm talking about.

pierlux said:

OT, but worth mentioning. This reminds me of Apple's lightning cable: it's smaller and nicer than the previous one, but not idiot proof. If you leave it plugged to the charger hanging free, sooner or later the exposed contacts will touch a conductive material (metal, tin foil, aqueous solution, whatever) and a short circuit is guaranteed. It's not dangerous (5 volts), but potentially lethal for the cable and/or the charger.
http://www.macrumors.com/2014/03/04/lightning-cable-corrosion/

Volker said:

Hi Roger!

Excuse me for not knowing what Freefly or MōVI is. After googling it: Ah, OK. A digitally stabilized gimbal with brushless motors. Steadycam 2.0, if you want to put it that way. The product looks pretty cool, quite well engineered.

From that point of view, I can hardly believe that anyone would use such a crappy adapter to charge the LiPO cell(s) or build a charger that requires these banana plugs. Outside a laboratory, that is. There are 1'000'001 ready-to-use solutions available that avoid short circuits, reverse polarity or protection against accidental contact and they are not even more expensive.

What would the input voltage be? 9V? 18V? Charging current? 5A? 10A? You probably don't want to invest in a rocket-science PEN.0F.302.XLM or likewise from LEMO (http://intra.lemo.ch/PartSearch?app=&mat=&ref=PEN.0F.302.XLM&lang=en), but even the good old DC connector would do: http://download.siliconexpert.com/pdfs/2010/11/1/3/38/36/261/scf_/manual/760bk.pdf.

So I really can't understand why a company deliberately wants to fail on the finish line.

Cheers,
Volker

Big_Eater said:

I'm rather surprised that the Freefly people have not dropped by this blog to comment. Do they know about all this?
Also, can you carve or stamp the positive and negative symbols into the Sugru before it hardens to let people know the polarity?

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