[NSRCA-discussion] Some more lipo fire videos - Explosion Proofvault

Fri May 26 03:45:40 AKDT 2006

Electrical enclosures in flammable / explosive vapor areas are often maintained at positive pressure with nitrogen (and this system alarmed) to ensure that there is no fuel for ignition (nor oxygen to support combustion) in the enclosure.

While safety cans and / or vented storage cabinets are a good idea for liquid fuels - their cost generally prevents home use (most won't pay $85 for a gas can or hundreds for a cabinet). Careful practice (and often luck) seems to work OK in home use.

The same is true for LiPo's - most folks won't pay big bucks for some sort of vault and probably don't need to. We do need to understand that there is a potential for fire (and disbursement of burning material) if all goes wrong, and provide reasonable containment / location to accommodate such an occurrence. 

With the cost of the big packs being what it is, I really want to make sure practice / equipment doesn't allow catastrophic failure in the first place.

Earl

  ----- Original Message ----- 
  From: brian young 
  To: NSRCA Mailing List 
  Sent: Thursday, May 25, 2006 10:11 PM
  Subject: Re: [NSRCA-discussion] Some more lipo fire videos - Explosion Proofvault

  Yeah a fuel-air bomb isnt among the most potent explosive?

  I worked in petrochem design for awhile, doing projects in areas where we had electrical sources in explosive areas. The explosion proof electrical service we placed actually could contain gas and ignite within the box, and the box would vent but the seal of the box was controlled so the flame was extinguished as it exited the box and would not ignite a source outside the box. 

  I was an ME design coordinator so only know the basics of this from the EE guys explanation.  Im sure others follow this list that know more than me ;-)

   I have wondered since the lipo technology and the fears came whether there was any market for something like this. If someone ever screws up and sets a pattern pack off in a garage/car/trailer something like this might help contain better than sand bags, cinder blocks, crocks, etc....just a thought. 

  Price might be high but cheaper than a lot of other things and if all the safe gaurds go wrong this might offer one last hope. 

  Earl Haury <ehaury at houston.rr.com> wrote:
    All energy sources present a potential risk and must be handled accordingly. The LiPo fire videos demonstrate the potential for this source. Anyone have a video of a gallon of glow fuel or gasoline or Jet-A being ignited - say by a 12v gel cell shorting against a can? I guarantee it will be even more spectacular than the LiPo!

    My point is that we tend to become complacent with things we are familiar with. Gasoline is an extremely dangerous material - yet most of us are comfortable in using it and often get by with potentially fatal practice. Only the narrow flammability range of gasoline saves us. (And no - the lubricant added for model engines doesn't make it more safe.)

    How many have gallons of glow fuel stored in their home or garage? Not a wise thing - but again we get complacent after a period of good luck. (Then there were my trap shooting days when I bought gunpowder in multiple 12# containers - guess where that was stored.)

    The LiPo simply presents a new set of risks and failure modes. Overcharge the things or short them (dents can do this internally) and things get nasty. Care in handling / charging / using these things is mandatory - and yet we all make mistakes. Shorting them will get your attention immediately (extreme care is required when attaching leads). Crash damage has a high likelihood of shorting them internally / externally - so extreme caution is need here also (think gasoline dripping on sparking battery leads). The overcharge issue can be a matter of carelessness or of charger failure. Containment during charging is a really good idea, as well as a charge system that prevents overvoltage in individual cells (sets). 

    I suspect that most charging errors occur with folks using a variety of size packs. The other (well discussed) issue is charger mis-identification of cell count due to trying to charge a charged pack. A little less risk if pattern equipment only is used. (I choose to use separate chargers for the large power batteries and the radio power battery to limit the error factor.) The inclusion of cell "taps" for monitoring cell (set) voltage and balancing also go a long way toward ensuring that a pack is healthy and behaving normally during charge. 

    Bottom line - LiPo's present risk in the same range as other "fuels" - the safety procedures are no more or less important - but they are different!

    Earl

      ----- Original Message ----- 
      From: Tommy Scarmardo 
      To: NSRCA Mailing List 
      Sent: Thursday, May 25, 2006 10:09 AM
      Subject: Re: [NSRCA-discussion] Some more lipo fire videos

      I saw some pictures on a Japanese web site of an electric Impact which caught on
      fire and was completely destroyed while in the air flying presumably from too much
      load on the batteries or maybe a short. I wish I could read Japanese to find out exactly
      what happened.

      tommy s

      Larry <ledunn at centurytel.net> wrote:
        Maybe this is a good time to share these videos - if you haven't seen them they are well worth watching. Look on the left side of the bottom of the main page.

        Lipos fires 1,2 & 3

        http://www.utahflyers.org/

        I have become a bit of a lipo safety nazi lately - ever since I had my first lipo fire a couple of months ago.

        I have been using lipos since the early days. I'm a smart guy with a background in electronics and all things electrical. I am known as "Electric Larry" at our field. I teach other people how to do electrics and what NOT to do. I'm the go-to guy in our club. In spite of all that - I had a major lipo fire a couple of months ago that destroyed almost all my RC gear and planes and came very close to burning down my house. It was 100% my fault. I was doing too many things at once and had become casual/careless in my care of lipos.  I had gone YEARS with no issues at all and had gotten complacent.

        My equipment and charging routines are now 100% improved.

        Be careful guys.

        Larry
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