XDCam Batteries

[Alister Chapman]

There will still be complete Li-ion cells in each part of the battery pack and these can still fail and start a fire. The problem with Li-ion cells is the way they fail. Most battery cells get hot when overloaded but nicads and ni-mh and similar break down and get less efficient as they over heat, wheras Li-ion cells produce more and more current as they heat up, so they get hotter still and you get a thermal run-away. Eventually they catch fire and the chemicals in the cell itself will burn fiercely. Nicads don't burn. This can happen with any Li-ion cell, even a cell phone battery. Clearly you don't want fires starting on planes and that's why the amount you can take on board is limited, to reduce the risk to an acceptable level.

[Thierry Humeau]

I love the Pro-X from Switronix ( www.switronix.com ). I have a few 130s . They are well made and last long.

Thierry.

[Greg Boston]

Originally Posted by Alister Chapman

There will still be complete Li-ion cells in each part of the battery pack and these can still fail and start a fire. The problem with Li-ion cells is the way they fail. Most battery cells get hot when overloaded but nicads and ni-mh and similar break down and get less efficient as they over heat, wheras Li-ion cells produce more and more current as they heat up, so they get hotter still and you get a thermal run-away. Eventually they catch fire and the chemicals in the cell itself will burn fiercely. Nicads don't burn. This can happen with any Li-ion cell, even a cell phone battery. Clearly you don't want fires starting on planes and that's why the amount you can take on board is limited, to reduce the risk to an acceptable level.

Nigel, I'm aware of what you are saying. But the batteries I referred to SEPARATE the cells. That's the whole idea behind the design, to become airplane safe. In many batteries like those for laptops and cellphones, there is only a thin mylar sheet that separates the positive and negative side of the battery internally. It was contaminants in the mfg process that rubbed through over time from vibration causing a short that plagued the Sony made batteries.

BTW, any battery which has a full charge can burn if the contacts or the two plates internally short out. Lithium Ion batteries just have the highest energy density per area at the moment. So if they short, they can produce more heat energy for their size, hence the limitation on size, or more correctly, amount of lithium content (8 grams or less) for airplane transport. I send you a link to the site as soon as I remember where it was so you can see what I'm talking about.

-gb-

[Simon Wyndham]

Yep. The reason why the AB's are so expensive is because of all the computer technology inside that constantly monitor the condition of the cells and act to prevent any potential disaster.

[Alex Dolgin]

Originally Posted by Greg Boston

Nigel, I'm aware of what you are saying. But the batteries I referred to SEPARATE the cells. That's the whole idea behind the design, to become airplane safe. In many batteries like those for laptops and cellphones, there is only a thin mylar sheet that separates the positive and negative side of the battery internally. It was contaminants in the mfg process that rubbed through over time from vibration causing a short that plagued the Sony made batteries.

BTW, any battery which has a full charge can burn if the contacts or the two plates internally short out. Lithium Ion batteries just have the highest energy density per area at the moment. So if they short, they can produce more heat energy for their size, hence the limitation on size, or more correctly, amount of lithium content (8 grams or less) for airplane transport. I send you a link to the site as soon as I remember where it was so you can see what I'm talking about.

-gb-

Li-Ion are inherently flammable because the material itself is flammable, regardless of external shorts. It is different from any other battery chemistries in this respect. There is no way to separate a Li-Ion cell to make it safe. You probably think of making the pack smaller by separating it into 2 halfs. There is a transportantion industry standard, limiting the amount of Li-Ion in a pack. This trick would help it to sneak it "under the radar."

[Greg Boston]

Originally Posted by Alex Dolgin

Li-Ion are inherently flammable because the material itself is flammable, regardless of external shorts. It is different from any other battery chemistries in this respect. There is no way to separate a Li-Ion cell to make it safe. You probably think of making the pack smaller by separating it into 2 halfs. There is a transportantion industry standard, limiting the amount of Li-Ion in a pack. This trick would help it to sneak it "under the radar."

That's true Alex about Lithium. No, the batteries I saw aim to separate the two materials so that the possibility of an internal short that would start that Lithium fire is removed. I'm not saying the airline industry will buy into it and accept this method of 'fireproofing' li-ion batteries, but I do think it's a clever idea if it works.

-gb-

[Alex Dolgin]

Originally Posted by Greg Boston

That's true Alex about Lithium. No, the batteries I saw aim to separate the two materials so that the possibility of an internal short that would start that Lithium fire is removed. I'm not saying the airline industry will buy into it and accept this method of 'fireproofing' li-ion batteries, but I do think it's a clever idea if it works.

-gb-

Just am trying to separate facts from fiction :-)
I am very closely involved in the battery industry, on the technical level. If somebody had invented and delivered a solution like that, it would be on the first pages of all the publications I am getting...

[Greg Boston]

Originally Posted by Alex Dolgin

Just am trying to separate facts from fiction :-)
I am very closely involved in the battery industry, on the technical level. If somebody had invented and delivered a solution like that, it would be on the first pages of all the publications I am getting...

It's there, I just can't remember the site I was browsing. I'm thinking I followed a link asking about the quality of a particular LCD monitor, and then found the batteries on that same site.

Good to have your tech knowledge on batteries. I myself spent 25 years as a tech in the semiconductor industry and have worked with some very nasty stuff, chemically speaking.

I gotta find that website so I can send you guys the link. I'm looking. I tend to keep my browser history limited so that's no help.

-gb-

[Alister Chapman]

You can't possibly separate the negative and positive parts of a cell. The cells rely on a chemical reaction between the different chemicals within the cell. As well as being highly flammable the chemicals in Li-ion cells are about as toxic as you can get. While you may be able to separate individual cells, which will reduce the risk, you can't get away from the fact that once a Li-ion cell gets hot enough (for whatever reason) the chemicals inside the cell will ignite in an intense and possibly explosive manner. Nicad and the like simply don't do this, the chemicals used don't just burst into flames. A li-ion cell submerged in water can also self-ignite, there also extremely difficult to extinguish.

[Greg Boston]

I still can't find the site I was on, but the more I think about it, they were probably separating the pack into smaller pieces to 'slip under the radar' as Alex stated.

From the diagram I remember, it looked like they were splitting the battery in a manner that each piece was only offering an external connection of positive or negative to eliminate them being close enough to each other to get shorted out accidently from an exterior position.

But yeah, I agree that you can't separate the two active chemicals within each cell. Maybe I worded my original posts wrong.

What I meant about other battery types being dangerous was that a direct short, or reversed connections on a fully charged alkaline, nicad, NiMH, lead acid, what have you, may not cause it to flame up internally like lithium, but to get hot enough to ignite any flammables in close proximity to the battery. I've seen lead-acid batteries explode when shorted out. It's the massive current flow from a short through the internal resistance of the cells that generates heat, which creates more resistance, which creates more heat, ad nauseum in a thermal runaway until the casing usually ruptures and starts to leak.

Anyway, we've drifted off topic about which batteries are good for running your XDCAM camera with.

-gb-

[Alister Chapman]

Originally Posted by Greg Boston

I've seen lead-acid batteries explode when shorted out. It's the massive current flow from a short through the internal resistance of the cells that generates heat, which creates more resistance, which creates more heat, ad nauseum in a thermal runaway until the casing usually ruptures and starts to leak.-gb-

Yes any cell or battery can start a fire or explode. But most cells when they overheat the resistance as you correctly say climbs. Increased resistance will REDUCE the current flow (ohms law, I=V/R), which reduces or at least prevents complete thermal runaway. Li-ion cells are completely different, the resistance falls as they heat up, the current increases quickly and you get true thermal runaway follwed by self ignition. Correctly designed Nicad and NiMh cells should not explode as they should have overpressure vents. Lead acid cells can explode as they produce hydrogen gas. As you say Greg we have gone off topic, but it is important that people understand why Li-ion batteries are so much more dangerous than Nicads and NiMh.

[Greg Boston]

Originally Posted by Alister Chapman

but it is important that people understand why Li-ion batteries are so much more dangerous than Nicads and NiMh.

Totally agreed, and the press has done a good job of educating the public with the high profile battery recalls.

Here's a good read about what's being done.

http://www.technologyreview.com/read...nergy&sc=&pg=1

More links to Lithium Ion horror stories

http://wcco.com/consumer/local_story_148150249.html

http://news.com.com/2102-1041_3-5942...=st.util.print

http://www.usa.canon.com/consumer/co...0&keycode=2111


And here is some good 'factual' reading...

http://www.macosxhints.com/article.p...30314081843218

This should be enough information for everyone to take to heart.

Looking back at my original statement about the website showing these batteries, I did say separation of positive and negative 'material' whereas I should have said separation of positive and negative 'external connections' which is where this whole discussion drifted of topic.

Mea culpa,

-gb-

[Alex Dolgin]

Originally Posted by Greg Boston

Looking back at my original statement about the website showing these batteries, I did say separation of positive and negative 'material' whereas I should have said separation of positive and negative 'external connections' which is where this whole discussion drifted of topic.

Mea culpa,

-gb-

No problem, I wish you were right :-)
Would take care of many headaches in the battery industry...

[Ivan Snoeckx]

Originally Posted by Greg Boston

I still can't find the site I was on, but the more I think about it, they were probably separating the pack into smaller pieces to 'slip under the radar' as Alex stated.

Greg,

The batteries you are mentioning are from SWIT.
Their large capacity (S-8170S) bricks can be devided in two pieces, so that you can stay under IATA his norms.

http://www.swit-battery.com/swit2006...ig/s-8170s.gif

Greetings!