Aug 04, 2003, 10:21 AM
Bit-Twiddler and Flyer
Ken,

Sorry for your loss.

Maybe others can share their "rules of thumb" for
battery transport, storage, handling and charging.

1) Always remove jewelry rings, bracelets, watches,
necklaces. Gold is a GREAT conductor. A short of
any battery pack through jewelry will cause burns
and may remove body parts. Do not put batteries
in your pocket as loose change or keys can cause
a short.

2) Always assume a battery is loaded and treat it
just like a loaded gun. Even discharged cells may
have enough potential to cause fire in the event
of a short.

3) Storage/Transport? How do you store cell packs,
foam lined coffee can? Glass jar with foam? Any non-
conducting cushioning insulators out there?

4) Check and double check your charger settings.
Never leave a charging battery unattended. Never
charge indoors. Any others?

-- ggunners
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Aug 04, 2003, 10:43 AM
luc
luc
I plant balsa sticks too
luc's Avatar
I use plastic bags to wrap packs. as such I can't have short circuits between 2 different packs.
Aug 04, 2003, 11:24 AM
Live to ride... and fly!
Tres Wright's Avatar
Ken, that is a terrible story, very sorry to hear it happened to you. Perhaps others will take note and be careful with ALL battery packs. They should be handled and treated with great care, especially when charging.

I nosed in a plane that was running a 2s2p 1200 setup. The front pack immediately vented and got VERY hot. I set it aside on concrete expecting it to vent for a few minutes. 20 minutes later it was STILL venting and STILL very hot! I found a container and dunked it in water. These things can contain a lot of energy and can react unpredictably after being subjected to unusual forces like a place crash. Best to treat them like explosives, store and charge in protected areas with no combustibles.
Aug 04, 2003, 11:38 AM
Build'em and Crash'em
Ken Lapointe's Avatar
Ken,

sorry to hear about your loss.

As we e-flyiers keep wanting better batteries we will have to realize that what we are asking for is higher power density. At some point higher power density and higher total stored power become a hazard.

Once the cost of higher power density batteries comes down and everyone starts using them I expect to see more stories like this.

We need more information on the best way to store and charge these things. Maybe better packaging is even waranted.


Ken
Aug 04, 2003, 12:06 PM
Registered User
rtideas's Avatar
Ken,

That truly sucks.

NiMHs are a risk as well. I dorked in a foam plane. I had a large coin that balanced the plane in front of the 1800AA NiMH pack. Upon impact, the coin dented one cell, shorting itself out. I picked up the plane not knowing. Looked at the battery, and noticed the shrink wrap was cracking. I pulled the pack out and as I was examining it in my hand, I noticed a cell venting. Too late. KA-BLAM!!! The cell exploded with the sound of a shot gun. My left ear rang for over an hour. I was fortunate no body parts, or my face was in the line of the explosion.

A guy I fly with was charging a small NiMH pack as he was driving. He noticed a smell and stopped. The pack was overcharging and extremely hot. He unplugged it and go it outside to the ground. Luckily no explosion but his car smelled for a bit.

All energy storage devices are risky. This is another warning to all fliers to be aware.

Again, truly sorry for your loss.

rt
Aug 04, 2003, 12:56 PM
Aerial Shutterbug
RMihara's Avatar
Hi Ken,

This is terrible news and I'm also sorry to hear of your loss. I hope all will be replaced and you find yourself back up soon.

This definitely brings another reminder that Lithium-Polymer Technology, while relatively safe during recharge do not have any safety mechanism built into them during discharge or damage.

Sure the soft packaging addresses the venting/pressure build-up issue but by no means provides adequate mechanical protection, that is up to the end user. Perhaps this is a good time for all of us to start thinking about how to mechanically protect these cells - much like how we would wrap a receiver in a foam blanket.

Accidents/crashes do happen whether by pilot error, electronics failure or simply being 'shot down'. This is another wake-up call indeed.

Roger
Aug 04, 2003, 01:31 PM
Registered User
Ken, thank you for sharing your bad experience with us. I'm sorry for your material loss, but thank goodness no one was injured. Crash damage to lithium cells and subsequent cell venting has been discussed in a few other threads that I've read here recently. Putting this together with previous threads about unattended charging of packs near combustible materials resulting in a few fires already had me thinking in terms of being especially careful with any lithium pack after a crash.

We are still on the cutting edge of learning all the things that can go wrong with lithium cells when they're used in experimental applications. Sharing the results of these experiences with other members of the e-flight community through forums such as this one will help spread the word much faster than possible before the advent of online discussion groups.

In addition to the previously accepted safety rule of never leaving a lithium pack unattended near combustible materials while charging, we now know that we should never leave one unattended near combustible materials after a crash. As has been discussed in previous threads, we should not let these unfortunate but relatively rare incidents create panic and fear. If we learn our lessons and follow basic safety rules, there's no reason not to continue to experiment with this extremely useful cell technology.

Based on the incident described in this thread, I'm going to look again at how I handle all of my Li-ion and Li-poly packs under all circumstances. I think we all should.
Aug 04, 2003, 01:37 PM
Purveyor of RC-Opiates
LightFlightRC's Avatar
I agree completely Dave,

I will be appending my battery manuals to stress cation after crashes.

We are all very sorry to hear about your loss Ken. Thankfully the dog was able to escape.

-Dave
Aug 04, 2003, 01:43 PM
AMA 148796
Thanks guys. A couple bottles of good wine last night helped.

All the credit cards are re-ordered, I've a driver's license now, and a rental car.

Now to call the FAA and get a new ticket, that was the original.

Off to the dealer today to look at cars - seems they've gone up in the last four years.

Ah well, no one was hurt.

And the fire was interesting to watch. Ever seen a tire explode?



Ken
Aug 04, 2003, 02:27 PM
Registered User
Dave Grife's Avatar
Yes Ken,

Thank-you very much for sharing your information with us all.

Sometimes our setbacks can indeed help others even more than our success.

I'm sure that your information sharing will probably help prevent similiar accidents for many other modellers.


Thank-you again very much,

respectfully,

-DG
Aug 04, 2003, 03:11 PM
Registered User
Sorry for your loss and thanks for helping us be more careful.

About how big were the cells involved? I understand you don't wish to give the manuf.'s name, but are we talking about large packs or small?

John
Aug 04, 2003, 03:47 PM
AMA 148796
The cells were a 3S2P pack of 1200s (total 2400mah). Preconfigured.

Aug 04, 2003, 03:56 PM
Senior Moment Member
Ken,
Sorry to hear about your accident. That must be a terrible experience to go through, but as said before, thankfully only material goods were lost, and they can be replaced.

We all get a little lax as time goes on and familiarity increases. I have always been very careful with Li technology, yet sometimes catch myself doing things I shouldn't do. But I've never had an accident. By relating your experience you help to bring the reality back to everyone that it can and does happen, and at the least expected time.

Jimmy
Aug 04, 2003, 04:22 PM
Registered User
sneu's Avatar
I will bet that after a few more problems like this on that the AMA will get involved on the safety side due to possible lawsuits. Lithium batteries can provide very good performance but the safety issue for the hobby user has been largely ignored.
I believe that some standards need to be set for the lithium battery hobby business.

In dealing with lithium battery in industry I have found that most of the larger manufactures will not sell just cells without an engineering evaluation of the application along with the charging system and the safety systems. This comes from the early problems with lithium battery fires in laptop computers and such. If you look at any consumer lithium powered device you will find safety devices.

Steve
Aug 04, 2003, 05:21 PM
Bit-Twiddler and Flyer
Quote:
Originally posted by sneu
If you look at any consumer lithium powered device you will find safety devices.
Unfortunately, to make the LiPoly "safe" may require the addition of protection in the form of a metal casing to prevent inadvertant crashes from damaging the cells. That casing may add enough weight to remove the benefit of today's lighter cells. We can only hope that engineering a "safe" LiPo battery doesn't make it too heavy to use.

-- ggunners


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