So you're going to use Lithium
Polymer Batteries ??
PLEASE BE VERY, VERY CAREFUL !!!!
By: Tom Laureanno, AMA #751764
This is what could possibly happen if a Lithium Polymer battery
ignites.... Over $40,000 of damage
between R/C gear and smoke/soot damage.
The first picture below is how it all looked before the
I came home from work the evening of Wednesday November 9th, 2005 around 4:30 pm, pulled into my garage and upon getting out of my car, I decided to cycle and charge some R/C Nicad batteries, while also charging some Lithium Polymers (or LiPos). I plugged in my Astroflight Model 115D peak charger and connected a 6 cell 1800maH Duratrax Piranha pack to it and placed it on trickle charge. I then took my LiPo packs out from my ceramic storage container (similar to a medium flower pot) and placed them on my bench top. I then powered on the 12V regulated power supply which was connected to the Astroflight Model 109 LiPo charger (purchased 2 months prior), connected one of the 1500maH 3-cell Kokam packs to the charging leads and placed the pack into the ceramic container. I watched as the charger recognized the 3 cell pack. I then proceeded to line up the other LiPo packs on the bench while also observing the charger as it initially analyzed the LiPo pack (it usually takes 3 minutes, according to the manual). After this 3 minute period, I heard the charger then go into its normal charging mode (it beeps once). I also noticed that the charger was charging at a 1300mA rate and I was about to set it to 1500mA (1C) but did not (a little lower can't hurt I thought). I then left the garage and went upstairs where I set up my laptop on the breakfast nook table. I got something to drink and seated myself at the table with my laptop (I had some work to do.... still).
Around 20 minutes later, I all of a sudden heard my garage door unexpectedly open, which was directly below from were I was seated. "Hmmm", I thought, "the only time I hear this open Is when my girlfriend comes in", as she has a remote for it. But hmmm... I thought,.. "she's usually still working at this time". 5-6 seconds after hearing the garage door open, I then heard my smoke detector going off downstairs (directly outside the door leading into the garage). I momentarily thought,... "could my girlfriend be messing with my head?"... "but why would she be holding in the fire alarm test button..?" I thought. A second later, I heard a pop and a snap from downstairs and I immediately launched myself out of my seat and ran down the stairs. Upon coming to the door leading to the garage (which was ajar), I saw a wall of FLAMES! The only image I really remember is my entire R/C airplane wing rack (made from PVC covered with foam, holding 4 wings), engulfed in one big flame, wings and all! I quickly went into fire fighting mode and knew exactly where I placed a new fire extinguisher that I had recently purchased (2 weeks prior). Lucky for me, it was 4 feet away. I grabbed it and remember struggling with the safety pin a bit before I could engage it. I then emptied the entire fire extinguisher onto the now ever growing fire and was very lucky to put most of it out. As soon as the extinguisher emptied, more flames began to develop. The next fire extinguisher I remember having is one for my kitchen. I "flew" up the stairs, grabbed the extinguisher from the counter and as I was running down the stairs, got it all ready (still struggling with the darn safety pin) and upon entering the garage, emptied this second extinguisher onto the fire. By the time it took me to run upstairs and get back down (15 seconds most), the fire continued to quickly spread along the back wall, engulfing all the airplanes (foam and balsa) I had hanging from their holders attached to the wall, including 3 airplanes I had in a PVC rack (similar to the wing rack). I managed to knock the fire down completely this time but had some embers still burning. I ran out the opened garage door and quickly turned on the garden hose and began to spray down the smoldering fire. As soon as I started spraying, I heard my neighbor yelling "Tom, is everything OK?". I answered "NO Joe!...Call the Fire".... I should have said "Fire Department" but I think I was so out of breath I couldn't. Nevertheless, he understood, relayed this to his wife and came up the driveway to help out. I handed him the hose and said "Joe, I'm running upstairs to grab another extinguisher and be sure there is no fire upstairs". After getting the extinguisher, I checked the walls, the floor, and even went out on the upper deck to check the exterior... all looked ok. I ran back down and met Joe and the fire looked like it was all out. About 30 seconds later, the fire engines began rolling down the street.
The fire fighters proceeded to knock down the sheet rock to be certain the fire had not spread, tearing half the wall and part of the ceiling down. They then investigated the cause (for around 45 minutes) and came to the initial conclusion that it was a general electrical fire. I myself am almost certain it was from the LiPo pack exploding (for what reason, I do not know). This was a fairly new pack (1/2 yr old, 20 cycles if that) and the charger being used is supposedly "state-of-the-art". I had placed the battery pack into the "flower pot" but did not place the cover over it (as I always use to do but had been slacking). I believe the battery explosion (i.e. fire ball) lit the wings on fire and this spread rapidly to the other planes and wings that were hanging. Nevertheless, one thing you should not do is charge these any where near flammable materials... especially balsa, Monokote and foam! Please be sure you always STORE, CHARGE and TRANSPORT (yes, all 3) Lithium Polymer batteries in a safe, fire-proof container that is "fully" contained (i.e. a lid, cover, etc...).
Oh, and in case you are wondering why the garage door opened by itself, it appears that the fire and heat generated along the ceiling must have melted the bell wire, triggering the garage door opener. Although this might sound good in that the smoke would leave the garage, in fact, the wind fueled the fire and blew smoke and soot into my house since the door between the garage and interior was left open. Boo. Heck, I still have my health, and luckily, even my house! Everything else is replaceable. This has been a very humbling experience, as I'm an electrical engineer who usually puts safety first. It goes to show you that this type of accident can happen to any one.
And one last safety note... Please be sure you have at least a couple of fire extinguishers in your house and be sure they are checked often! (actually, practicing with them is a good idea too, simply to familiarize yourself with its operation). They could definitely save your house, if not your life. If I did not have these, my house certainly would had burned down!
So, if you really have to use
Lithium Polymer batteries, be sure you are very, very safe !
Do not become complacent like I did.
Astroflight charging operation, I did not see if when in stage 2, it was
still recognizing the 3-cell pack. I only noticed the current was 1300maH.
Also, I do not know if the pack was already fully charged ("topped") or not. If I
was to guess, I would think it was depleted as it was one of my newer packs
I had been testing. I have been charging LiPos for years now (been
using them for 4+ years) and never had an incident, not even a warm or puffy
pack. I have been using the Triton charger with temp probe and all and never
had a pack heat up or damaged in any way. My demise was not covering the
pot. I would hate to think it was the charger but I know others say there
had been 4-5 LiPo fire incidents so far this year that included the AF 109.
I passed up the AF 109 many times because I did not like the auto-cell
detect feature; I like to be in control. I started using 6s2p packs in my
larger planes and needed a charger that would handle this capacity, hence I
splurged for the AF 109.
Wow, what a wake-up call!
P.S. I received
numerous emails regarding this webpage and accident and appreciate most of
will always read more into it than they need to... oh well. One the
nicest emails I received was from Kevin Kelley, the manufacturer of the
"Battery Bunker". Kevin was so nice he even offered me a Battery
Bunker container for charging my LiPos in the future. Let me say...
this container is literally a "work of art", in fact, I almost don't want to
use it for my LiPos! Really, it's a great container and I think
everyone should have one, especially if you plan to safely charge your LiPos
in your house. You can check it out at his
Click here to go back to Tom's DIYRC.com webpage...