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Old Aug 10, 2004, 11:00 PM
A Clinger
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Butte, MT
Joined Sep 2001
7,075 Posts
. I was one of the 'wait' and see guys; but I have since bought several LiPo packs and a 'dedicated' LiPo charger ( Astro 109 ) . If I buy another charger it will also be 'dedicated' to LiPo. Less mistakes that way (several times on my Triton, I've spun the dial as I pressed and ended up discharing a NiMh pack instead of peaking it ) . Anyway, I'll never look back -- the benefits are to great to ignore. FWIW, I do charge in my basement in a fire safe. I do have a Fire extinquisher near by and a smoke alarm setup over the charging area. And my point is? Just know the technology, respect it, and USE IT ........ My two cents .
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Old Aug 11, 2004, 02:37 AM
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Sacramento, CA
Joined Sep 2003
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Quote:
Originally Posted by SharksTooth
It's not the batteries fault that a user does not follow directions. . . . .They are just like guns. A gun doesn't just decide it's going to go off all by itself, it takes somebody pulling the trigger to make that happen. Li-Po's are exactly the same in that respect...they are as safe as anything until a negligent user goes and causes them to go off. The only reason to fear Li-po's would be if you were planning on not following directions, or just plain paranoia. In either of those two cases, it's better to stick with obsolete technology.
Tthe law holds a manufacturer/vendor/distributor of a product to a higher standard -- i.e., if it is reasonably forseeable that the USE or MISUSE of a product can or will result in harm, then the MANUFACTURER/vendor/distributor have a non-delegable DUTY to ensure that their product addresses such uses or misuses in a way designed to protect the user from such foreseeable harm.

Simply: It is the batteries' fault if the average user/abuser's activities (charging, discharging, storing them on the seat of a hot car, etc.) result in harm (especially in a technologically advanced society where alternatives exist to protect the end-users from said harm.)

Read: Charge/discharge protections should be MANDATORY. Even if the user makes mistakes, the manufacturer/distributor/vendor can all be held liable for product use and/or foreseeable misuses -- especially if the vendor/distributor/manufacturer fails to take obvious steps to PREVENT uses or misuses from resulting in personal injury, property damage, or other such harm. Especially when the vendor/distributor/manufacturer need only view these forums occassionally to see that such USES/MISUSES are resulting in harm -- as the direct result of failures by them to protect!

I don't want to see all the manufacturer's pull out of this market any more than the next guy. But, it's time they stopped blaming the end users for "failures" while at the same time marketing a product which has the potential to detonate -- with absolutely no safety protections other than a "READ THIS FIRST" label affixed thereto.

I'm not a lawyer and won't respond to legal questions on this issue. But, to me, it's a product-liability lawyer's dream the minute someone gets killed or maimed by one of these "safe" products. Gun makers get sued all the time when their 38 specials explode in someone's hand -- when utilized in the product's intended fashion. Lipos have the same potential.

If the manufacturers, distributors, and vendors fail to take steps along these lines, I doubt their "luck" will hold out in the long run. Someone, unfortunately, will get hurt. We need the over-charge/discharge protection circuits, a safe charging container, better casings, chargers-for-dummies, parallel chargers, and many other such protections to idiot-proof these sticks of dynamite immediately -- if not sooner.

Either that or take them off the market until they are truly "safe". Or, as appears to be the case with most of these products these days, 1. pay up those liabilty insurance premiums, 2. blame the end-user, and 3. cross your fingers nobody dies.
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Old Aug 11, 2004, 02:49 AM
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Mostly in Norman, OK
Joined May 2002
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Quote:
Originally Posted by hall woo
Tiger Moth that can run 45 minutes on a 2 cell LI-ION pack with qualcomm charger. This a safe system because there is a safety circuit built-in the cells.

You won't find anything about fires with this system
No you won't, BUT if the on-board protection ckt decides to kick it, it will CUT OFF ALL POWER to the plane - ESC, motor, RX, servos and ALL. Granted it's 'only' a TM, but let's just say you're flying rather close to an interstate, freeway, road etc ...

It's as dangerous as putting a fuse between the battery and the ESC (with BEC).

DON'T do it.
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Old Aug 11, 2004, 03:42 AM
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Copenhagen, Denmark
Joined Apr 2003
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Hi

I have a similar history as FreeFlier.

I charged a 11s3p 6600mAh pack using a Schulze 636+ charger at 4A. Cell count was correct, the pack had less than 20 cycles, the pack had worked perfectly, the pack had no visible damage, the pack was never involved in a crach or mishandled by other ways, the pack was never overcharged or overdischarged. The pack was used in a Joker helicopter.

But during my last charge the pack didn't come up to full voltage before a center cell started to whistle. At that time my charger had put more than 6Ah into the pack. At the time I noticed it the pack was warm and cells located in the center of the pack was swelling. I moved the pack outside very fast and couldn't do anything but looking at how the pack turned into a pile of ash during the next 5 minutes. 6 foot fire spikes kept comming out of the pack for 5 minutes as each cell got on fire.

So be carefull. I have learned not to use lipo's again before I have a totally safe place to charge AND store my packs (iron box with bricks inside).

I have also learned to favor packs which are built from a serie of parallel groups of cells (instead of paralleling series of cells). In such packs each group of cells tend to balance each other because cells in parallel will always share a common voltage. An 11s3p pack is normally built by paralleling 3 11s1p packs. So if just one cell is bad and end up with a higher voltage than the rest of the cells mishap is sure to happen sooner or later. So avoid packs like 11s3p, 11s2p, 10s3p where cells cannot geometrically be arranced in to parallel groups close to each other. Use instead packs like 12s3p, 9s3p, 10s2p, 5s3p and so on.

Thomas
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Old Aug 11, 2004, 07:48 AM
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Sayre,PA
Joined Sep 2002
1,664 Posts
Quote:
Originally Posted by RD Blakeslee
Salt in the water probably contributed to the thermal runaway - it effectively shorted the already overheated pack.

...
This was my first thought when I first read this post. Why would you throw a fully charged pack into heavily salted water? This would cause a near dead short in the battery greatly exacerbating the problem. The only reference I recall to using saltwater was for disposal of the dead Li-Poly batteries.
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Old Aug 11, 2004, 07:57 AM
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jimsp,

the quote I used was abridged from Stew's initial post. In another part, he says:"Yes it did later occur to me that perhaps the pack should not have been placed in the water at that time, but the puffing., the odor, and liquid spots were quite unnerving, and rational thinking was at least a few minutes away..."

I can sure sympatize with that.

- RD
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Old Aug 11, 2004, 08:12 AM
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Joined Jul 2004
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Quote:
Originally Posted by jimsp
The only reference I recall to using saltwater was for disposal of the dead Li-Poly batteries.
How would one go about disposing a Li-Poly cell that is suspected of being damaged?

Let's assume that after a crash a cell is dented or otherwise damaged externally. Instead of taking chances with it, a prudent pilot may elect to dispose of the cell. What is the correct method? Discharge it until it is below 3.0V (under no load) (or other voltage?), then submerge in saltwater, then puncture and re-submerge?

I am asking in advance so that I know if/when the time comes...
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Old Aug 11, 2004, 08:16 AM
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Walled Lake, MI, USA
Joined Feb 2000
11,182 Posts
Quote:
Originally Posted by SharksTooth
There is not one single incident documented that was not result of user error or negligence.
This is only true by the very strictest definition of "user error" and "negligence." For instance, can someone be accused of user error or negligence if their pet chews on a Li-poly pack and damages it, causing it to fail? This situation was reported by at least one user on this forum. How about the user who reported having his charger set correctly, but a brief, not immediately noticed loss of electricity in the neighborhood caused the charger to reset to a different charge rate, causing the pack to fail. Can this be called user error or negligence?

The only way that every single Li-poly incident can be called user error or negligence is if every Li-poly user is expected to be on guard every second that any of thousands of possible incidents could cause a pack to fail catastrophically. This means always having every pack under close observation, or stored in a fire-resistant container where it cannot possibly cause any damage even if it does fail catastrophically.

There is no tolerance for momentary lapses of attention, nor for any human error in this scenario. If you make a mistake that results in pack failure, then you're guilty of user error or negligence. Unfortunately, humans are imperfect and are guilty of numerous errors every day of their lives. Most modern products are designed to protect the user from common human error. Li-poly cells, as used in e-flight, are near the bottom of the list in terms of protecting users from common human error.

Many people will not put up with the close level of scrutiny and care required to safely use Li-polys, nor should they have to. It's up to the industry to produce safer alternatives that provide more passive protection to users. It's been done with many other products that we use on a daily basis, and it will also be done for Li cells used for e-flight.
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Old Aug 11, 2004, 08:16 AM
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Joined Jul 2004
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Quote:
Originally Posted by RD Blakeslee
In another part, he says:"Yes it did later occur to me that perhaps the pack should not have been placed in the water at that time, but the puffing., the odor, and liquid spots were quite unnerving, and rational thinking was at least a few minutes away..."
What would have been the correct, rational response? Dump a bucket of sand on the battery?

(If the battery vents hope that the heat melts sand silicates into glass, then use glass to make jewellery, offer jewellery to spouse as a peace offering? )

Seriously, what is the correct rational response? And after the battery has cooled down (assuming it would not "vent with flame"), what then (see my post immediately above)?
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Old Aug 11, 2004, 08:34 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,107 Posts
Quote:
Originally Posted by SharksTooth
There is not one single incident documented that was not result of user error or negligence.
What you say is generally true. But, what about all those "ballooned on receipt" cells? It's true that we haven't had a report of one of them proceeding to the 'fire' stage, but something obviously is happening to them without modeler intervention. Maybe they were damaged during manufacturing. That brings up an interesting point. What if they were damaged during manufacturing but the cell hasn't ballooned yet. Could this be a fire in waiting? There have been several fires where the modeler has insisted that all charging parameters were correct. Perhaps these may have been caused by factory/shipping damage.
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Old Aug 11, 2004, 08:38 AM
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Walled Lake, MI, USA
Joined Feb 2000
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Quote:
Originally Posted by FreeFlier
I'm fairly sure the pack went to the bottom, but the cloudiness of the salt made it impossible to be completely sure.
Stew, your complete openness and honesty in describing this incident is highly commendable. It's not always possible in stressful situations to properly perceive and recall all of the details. Experiments have been done to test the ability of witnesses to recall details in high-stress situations. In such tests, various witnesses recalled details of the same incident that were totally at odds with what others recalled.

Now, if someone had a videotape of a Li-poly pack sitting on the bottom of a glass bowl under 10 inches of water with flames and sparks shooting from the pack on the bottom up to the surface and out into the air, that would be an entirely different situation. With no proof as to whether the pack was under 10 inches of water or floating on the surface, any discussion here about the failure mode of Li-polys in water would be purely speculative.
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Old Aug 11, 2004, 09:01 AM
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Joined Jan 2002
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Quote:
Originally Posted by Tojusi
What would have been the correct, rational response? Dump a bucket of sand on the battery? ...after the battery has cooled down (assuming it would not "vent with flame"), what then (see my post immediately above)?
Actually, I think Stew's response was correct: He quickly took the ONE ESSENTIAL action: He got the pack outside. As to whether, once he got there, it was a mistake to dispose of the pack quickly and spectacularly, by burning it in saltwater, I think is a judgement call.

Well, that got the disposal done in a hurry and I don't fault it.

- RD
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Old Aug 11, 2004, 02:44 PM
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Joined Apr 2003
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Quote:
Originally Posted by hall woo
Kit

Check out www.bayrc.com battery forum Ted Cooper knows about LIPO chemistry down to the last atom, I think, he is a battery junkie, blows them up on a regular basis for destructive testing id IS TJ COOPER


Ted Cooper's been MIA. Nobody knows where he's been, just right
after his started testing new Lipos. Hope he is... survived and well.
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Old Aug 11, 2004, 02:54 PM
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San Jose Ca / RSA flyer
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He is on vacation, be back next week, I believe
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Old Aug 11, 2004, 02:56 PM
Rhinebeck CD-99,00,01,02
Tom Smith's Avatar
New Bern, NC
Joined Mar 2001
3,060 Posts
Tojusi's question answered please!

I too have a pack gone south, I believe. Bought it used, a Kokam 3s 600mah Lipoly that was slowly loosing capacity. It was used to fly my FanTastic Models Gee Bee R1, pulling all of 2 amps. Last time used I was recharging at home and touched the pack after about 10 minutes on my Apachee 1500 charger and it had a hot spot on it. Unplugged immediately and ran outside with it. In my haste, I cut the leads off the pack, one at a time, of course, so now it sits in my back yard on a brick waiting for my next move. Cutting the plug off was not the right thing to do cause now I can't discharge it, the leads were cut off right at the shrink wrap covering. It cooled in a few minutes and has been out there for more than a week now, rain or shine. From the sounds of this thread, dropping it in a bucket of salt water doesn't seem to be the correct thing to do. Thought of taking my 22 and shooting a hole through it and standing back to see what happens, then dropping it in the bucket. Any ideas on what to do with this darn thing would really be appreciated. Tom
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