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Old Jul 05, 2004, 01:11 AM
Roger
Guest
n/a Posts
LiPoly fire

Ok,
"splain this one to me.
Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday.
Along with a new charger.
they were checked out on the system, and then put on the charger.
Charger is FMA Direct LIPO-203. 220ma charge, till the charger quit
charging (light went out), about 3 hours.
Took them off the charger, set them on the counter. 2 hours later, we
stuck them in the airplane-a "littlest Stick", and put the wing on.
Barreries are just in the airplane, not connected to anything. Just
setting there.
15 minutes later, smoke is pouring out of the fuselage. Batteries are
STILL not connected to anything.except that all the insulation is melted
off the things, and batteries are swolen up like to Nicad size. Big
mess. May have gorren so hot as to melt the reciever.
Any ideas? If these things are THAT dangerous, maybe we need a different
power supply.

Roger

Old Jul 05, 2004, 05:11 AM
The Natural Philosopher
Guest
n/a Posts
Re: LiPoly fire

Roger wrote:

> Ok,
> "splain this one to me.
> Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday.
> Along with a new charger.
> they were checked out on the system, and then put on the charger.
> Charger is FMA Direct LIPO-203. 220ma charge, till the charger quit
> charging (light went out), about 3 hours.
> Took them off the charger, set them on the counter. 2 hours later, we
> stuck them in the airplane-a "littlest Stick", and put the wing on.
> Barreries are just in the airplane, not connected to anything. Just
> setting there.
> 15 minutes later, smoke is pouring out of the fuselage. Batteries are
> STILL not connected to anything.except that all the insulation is melted
> off the things, and batteries are swolen up like to Nicad size. Big
> mess. May have gorren so hot as to melt the reciever.
> Any ideas? If these things are THAT dangerous, maybe we need a different
> power supply.
>


Overheating in the sun, or previously overcharged/overheated. Once the
pack swells up, it can get progressively likely to short internally.
Some newer packs seem more prone to this.

Undoubtedly it would be nice to have a power supply that didn't do this.

Do you leave glo fuel canisters in the sun too?

> Roger
>


Old Jul 05, 2004, 09:11 AM
jjvb
Guest
n/a Posts
Re: LiPoly fire

Not usually. However, the jug just swells a little. No fires.

John VB

> Do you leave glo fuel canisters in the sun too?
>
> > Roger
> >

>




Old Jul 05, 2004, 09:11 AM
tapio.linkosalo@helsinki.fi.invalid
Guest
n/a Posts
Re: LiPoly fire

another possibility is a bad solder joint in the battery pack. I've read
some reports of extremely poor solder jobs on ready-made packs, waiting for
the short to happen. I cannot tell if this is the case, but that is one
possibility.

It might be a good idea to make the lithium packs yourself, that way you
could wire them for "serial use, parallel charge" (bring each termina of
each cell to the connector, and have special connectors foo flight and
charge that re-organize the pack. Parallel charging of a lithium pack is a
good idea, as it automatically balances the back, which should be done after
every 3rd to 5th charge anyway.


-Tapio-
Old Jul 05, 2004, 11:11 AM
Paul McIntosh
Guest
n/a Posts
Re: LiPoly fire

Yes, I have left glow fuel canisters in the sun on many occasions. No one I
have known or flown with has ever experienced a fire because of it. And,
the heat in Arizona is FAR higher than in the UK. If LiPos will melt my
electrics merely by sitting in the sun, then I will look elsewhere.

--
Paul McIntosh
http://www.rc-bearings.com
"The Natural Philosopher" <a@b.c> wrote in message
news:ccb3q3$6s0$1$8300dec7@news.demon.co.uk...
> Roger wrote:
>
> > Ok,
> > "splain this one to me.
> > Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday.
> > Along with a new charger.
> > they were checked out on the system, and then put on the charger.
> > Charger is FMA Direct LIPO-203. 220ma charge, till the charger quit
> > charging (light went out), about 3 hours.
> > Took them off the charger, set them on the counter. 2 hours later, we
> > stuck them in the airplane-a "littlest Stick", and put the wing on.
> > Barreries are just in the airplane, not connected to anything. Just
> > setting there.
> > 15 minutes later, smoke is pouring out of the fuselage. Batteries are
> > STILL not connected to anything.except that all the insulation is melted
> > off the things, and batteries are swolen up like to Nicad size. Big
> > mess. May have gorren so hot as to melt the reciever.
> > Any ideas? If these things are THAT dangerous, maybe we need a different
> > power supply.
> >

>
> Overheating in the sun, or previously overcharged/overheated. Once the
> pack swells up, it can get progressively likely to short internally.
> Some newer packs seem more prone to this.
>
> Undoubtedly it would be nice to have a power supply that didn't do this.
>
> Do you leave glo fuel canisters in the sun too?
>
> > Roger
> >

>



Old Jul 05, 2004, 11:11 AM
Roger
Guest
n/a Posts
Re: LiPoly fire

atta boy, nP
Where, in my missive, did "hot" or "out in the sun" occur?
This was all indoors.
Idjut Limey! :-D
Roger

The Natural Philosopher wrote:
> Roger wrote:
>
>> Ok,
>> "splain this one to me.
>> Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday.
>> Along with a new charger.
>> they were checked out on the system, and then put on the charger.
>> Charger is FMA Direct LIPO-203. 220ma charge, till the charger quit
>> charging (light went out), about 3 hours.
>> Took them off the charger, set them on the counter. 2 hours later, we
>> stuck them in the airplane-a "littlest Stick", and put the wing on.
>> Barreries are just in the airplane, not connected to anything. Just
>> setting there.
>> 15 minutes later, smoke is pouring out of the fuselage. Batteries are
>> STILL not connected to anything.except that all the insulation is
>> melted off the things, and batteries are swolen up like to Nicad size.
>> Big mess. May have gorren so hot as to melt the reciever.
>> Any ideas? If these things are THAT dangerous, maybe we need a
>> different power supply.
>>

>
> Overheating in the sun, or previously overcharged/overheated. Once the
> pack swells up, it can get progressively likely to short internally.
> Some newer packs seem more prone to this.
>
> Undoubtedly it would be nice to have a power supply that didn't do this.
>
> Do you leave glo fuel canisters in the sun too?
>
>> Roger
>>

>


Old Jul 05, 2004, 01:11 PM
Bobby Galvez
Guest
n/a Posts
Re: LiPoly fire

Roger wrote:

> Ok,
> "splain this one to me.
> Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday.
> Along with a new charger.
> they were checked out on the system, and then put on the charger.
> Charger is FMA Direct LIPO-203. 220ma charge, till the charger quit
> charging (light went out), about 3 hours.
> Took them off the charger, set them on the counter. 2 hours later, we
> stuck them in the airplane-a "littlest Stick", and put the wing on.
> Barreries are just in the airplane, not connected to anything. Just
> setting there.
> 15 minutes later, smoke is pouring out of the fuselage. Batteries are
> STILL not connected to anything.except that all the insulation is melted
> off the things, and batteries are swolen up like to Nicad size. Big
> mess. May have gorren so hot as to melt the reciever.
> Any ideas? If these things are THAT dangerous, maybe we need a different
> power supply.


What brand of batteries?

BobbyG



Old Jul 05, 2004, 05:11 PM
The Shaw's
Guest
n/a Posts
Re: LiPoly fire

Would like to see a diagram of this "serial use- parallel charge"
wiring.!!!


V


<tapio.linkosalo@helsinki.fi.invalid> wrote in message
news:ccbfhs$mv2$2@oravannahka.helsinki.fi...
> another possibility is a bad solder joint in the battery pack. I've

read
> some reports of extremely poor solder jobs on ready-made packs,

waiting for
> the short to happen. I cannot tell if this is the case, but that is

one
> possibility.
>
> It might be a good idea to make the lithium packs yourself, that way

you
> could wire them for "serial use, parallel charge" (bring each

termina of
> each cell to the connector, and have special connectors foo flight

and
> charge that re-organize the pack. Parallel charging of a lithium

pack is a
> good idea, as it automatically balances the back, which should be

done after
> every 3rd to 5th charge anyway.
>
>
> -Tapio-



Old Jul 05, 2004, 05:11 PM
Roger
Guest
n/a Posts
Re: LiPoly fire

They are Kokam USA, marketed/distributed by FMA Direct.

Bobby Galvez wrote
>
>
> What brand of batteries?
>
> BobbyG
>
>
>


Old Jul 05, 2004, 05:11 PM
The Natural Philosopher
Guest
n/a Posts
Re: LiPoly fire

The Shaw's wrote:

> Would like to see a diagram of this "serial use- parallel charge"
> wiring.!!!
>


Its possible. You need twice as many connector pins as there are serial
cells.

One harness wires the cells in parallel for charging, the other in the
plane in series.

Its not a perfect solution, because shorting cells at potentially
slightly different levels of discharge can overheat them as well...

But they will all end up at the same state of charge.

>
> V
>
>
> <tapio.linkosalo@helsinki.fi.invalid> wrote in message
> news:ccbfhs$mv2$2@oravannahka.helsinki.fi...
>
>>another possibility is a bad solder joint in the battery pack. I've

>
> read
>
>>some reports of extremely poor solder jobs on ready-made packs,

>
> waiting for
>
>>the short to happen. I cannot tell if this is the case, but that is

>
> one
>
>>possibility.
>>
>>It might be a good idea to make the lithium packs yourself, that way

>
> you
>
>>could wire them for "serial use, parallel charge" (bring each

>
> termina of
>
>>each cell to the connector, and have special connectors foo flight

>
> and
>
>>charge that re-organize the pack. Parallel charging of a lithium

>
> pack is a
>
>>good idea, as it automatically balances the back, which should be

>
> done after
>
>>every 3rd to 5th charge anyway.
>>
>>
>>-Tapio-

>
>
>


Old Jul 05, 2004, 11:11 PM
tapio.linkosalo@helsinki.fi.invalid
Guest
n/a Posts
Re: LiPoly fire

The Natural Philosopher <a@b.c> wrote:
: The Shaw's wrote:

:> Would like to see a diagram of this "serial use- parallel charge"
:> wiring.!!!
:>

: Its possible. You need twice as many connector pins as there are serial
: cells.

Precisely.

: One harness wires the cells in parallel for charging, the other in the
: plane in series.

: Its not a perfect solution, because shorting cells at potentially
: slightly different levels of discharge can overheat them as well...

But if you parallel-charge them every time they are darn likely to be on the
same level of discharge every time you start charging...

-Tapio-
Old Jul 06, 2004, 07:11 AM
The Natural Philosopher
Guest
n/a Posts
Re: LiPoly fire

tapio.linkosalo@helsinki.fi.invalid wrote:

> The Natural Philosopher <a@b.c> wrote:
> : The Shaw's wrote:
>
> :> Would like to see a diagram of this "serial use- parallel charge"
> :> wiring.!!!
> :>
>
> : Its possible. You need twice as many connector pins as there are serial
> : cells.
>
> Precisely.
>
> : One harness wires the cells in parallel for charging, the other in the
> : plane in series.
>
> : Its not a perfect solution, because shorting cells at potentially
> : slightly different levels of discharge can overheat them as well...
>
> But if you parallel-charge them every time they are darn likely to be on the
> same level of discharge every time you start charging...


No. That would imply that they are all *exactly* equal capacity. No two
cells are exactly alike.

One could equally well argue that, if you make up your pack with exactly
equally charged cells (but of slightly different capacities) to start
with, then after discharging, no matter what their end point voltages
individually are, once charged up in series with exactly the same amount
going into each as has been taken out, they will all end up at the same
voltage fully charged.

Which is, in fact, more ore less why series charging does not blow every
pack up every time its used.

The devil is, as always, in the detail.

Parallel charging SOUNDS like a good idea to the simple minded.
Investigation of it shows it has as many flaws as series charging.

Ultimately cell voltage clamps and series charging is the way to go, or
INDIVIDUAL charging of cells one by ne to restore balance - but if
balance has been badly lost in a series pack, one should probably
investigate why. It may well be the first sign the pack is on its last legs.


Many of the problems being experienced are actually problems of
MARKETING. Packs are sold as '1000mA/h 10C discharge' but in reality,
whilst they may do that under carefully controlled tests, once, they are
liable to fail dramatically if exposed to it on a regular basis.

I use half the current draw and half the capacity that the marketing
alleges is safe. I haven't had any problems so far. LIPOS have so much
more power to weight and duration that I actually need, that there seems
no point in pushing them to the limits.




>
> -Tapio-


Old Jul 06, 2004, 07:11 AM
The Natural Philosopher
Guest
n/a Posts
Re: LiPoly fire

Six_O'Clock_High wrote:

> Roger,
> You were right the first time. Give up on D.H. he is probably too drunk to
> understand the FACTS you posted. Then he has to show his bad attitude about
> everyone in the world.
>

It is not always effective to judge everyine by your own stanrdas.

Just because you are high by six o clock every night, does not mean that
the rest of the world has to be the same.

This failure to move beyond childish solipsitic fantasies is known as
'ego centricity' - the feeling that you alone are representative of the
world at large. Its a Merkin thing.

Old Jul 07, 2004, 03:11 PM
Doug McLaren
Guest
n/a Posts
Re: LiPoly fire

In article <ccdu3u$rtt$1$830fa17d@news.demon.co.uk>,
The Natural Philosopher <a@b.c> wrote:

| Parallel charging SOUNDS like a good idea to the simple minded.

It sounds like a fine idea to those not so simple minded too ...

| Investigation of it shows it has as many flaws as series charging.

Really? I only see one big flaw -- when you hook the batteries up in
parallel, if there is any signifigant voltage difference between the
cells a possibly large current will flow until the voltages match. As
long as the cells are fairly close in charge level this shouldn't be a
big problem. You could also put some <1 ohm resistors in your
charging harness to keep the currents down between cells, but they'd
also slow down your charging rates.

Remember, we're talking about LiPo charging, not NiCd or NiMH.

| Ultimately cell voltage clamps and series charging is the way to go,
| or INDIVIDUAL charging of cells one by ne to restore balance - but
| if balance has been badly lost in a series pack, one should probably
| investigate why. It may well be the first sign the pack is on its
| last legs.

I can see where measuring individual cells from time to time after a
flight to determine how discharged they are is a good thing, but for
normal charging after each flight, I see no problem with charging in
parallel most of the time.

Certainly, charging in parallel every time is better than charging in
series every time and never checking individual cells (which is a much
more likely scenario, since many (most?) packs don't even include the
connectors needed to measure individual cells.)

| Many of the problems being experienced are actually problems of
| MARKETING. Packs are sold as '1000mA/h 10C discharge' but in reality,
| whilst they may do that under carefully controlled tests, once, they are
| liable to fail dramatically if exposed to it on a regular basis.

I've got some Tanic/iRate 2200 mAh 10C discharge packs, and they do
seem to handle 22 amp discharges with no problems. I don't fly wide
open throttle (WOT) all the time, but for sixty seconds or so it seems
fine. I've got hundreds of flights on them now, and I usually do at
least 60-120 seconds of WOT flight each flight. Often I fly the plane
(Combat Wings XE2) as a glider, and so my flights are 30 seconds of
WOT, 5 minutes of gliding, 30 seconds of WOT, 10 minutes of gliding,
etc. until either the batteries or I get tired.

I've used my Astroflight Whattmeter to measure the current used -- on
the ground, with my 3 cell pack and Astroflight 020, it'll use about
23 amps at full throttle. It should be a bit less in flight, but
still fairly close to the advertised limit.

| I use half the current draw and half the capacity that the marketing
| alleges is safe. I haven't had any problems so far.

They probably do last longer if you don't push 'em ...

| LIPOS have so much more power to weight and duration that I actually
| need, that there seems no point in pushing them to the limits.

Depends on what you're after. Certainly, I prefer not fly at WOT for
long -- I don't want to ruin my $75 pack. But so far they're doing
what they were promised to do with no problems.

--
Doug McLaren, dougmc@frenzy.com
People don't usually make the same mistake twice -- they make it three
times, four time, five times...
Old Jul 10, 2004, 01:11 AM
Ken Day
Guest
n/a Posts
Re: LiPoly fire

I have 10 Li Poly 1500 ma packs that are going in a pattern plane.
Five are 7.4 volts , 5 are 11.1 volts. I plan on wiring one 7.4 and
one 11.1 in series to attain 18.5 volts ,make 5 packs this way and
then wire the five in parallel to get 7500 ma. These will be hard
wired together terminating into one Deans ultra connector. I have
an Astro Flight 109 D and that will charge everything at once.
Have any of you wired this many this way ? Have you encountered any
problems charging ?

Thanks

Ken Day

On Mon, 05 Jul 2004 21:50:43 +0100, The Natural Philosopher <a@b.c>
wrote:

>The Shaw's wrote:
>
>> Would like to see a diagram of this "serial use- parallel charge"
>> wiring.!!!
>>

>
>Its possible. You need twice as many connector pins as there are serial
>cells.
>
>One harness wires the cells in parallel for charging, the other in the
>plane in series.
>
>Its not a perfect solution, because shorting cells at potentially
>slightly different levels of discharge can overheat them as well...
>
>But they will all end up at the same state of charge.
>
>>
>> V
>>
>>
>> <tapio.linkosalo@helsinki.fi.invalid> wrote in message
>> news:ccbfhs$mv2$2@oravannahka.helsinki.fi...
>>
>>>another possibility is a bad solder joint in the battery pack. I've

>>
>> read
>>
>>>some reports of extremely poor solder jobs on ready-made packs,

>>
>> waiting for
>>
>>>the short to happen. I cannot tell if this is the case, but that is

>>
>> one
>>
>>>possibility.
>>>
>>>It might be a good idea to make the lithium packs yourself, that way

>>
>> you
>>
>>>could wire them for "serial use, parallel charge" (bring each

>>
>> termina of
>>
>>>each cell to the connector, and have special connectors foo flight

>>
>> and
>>
>>>charge that re-organize the pack. Parallel charging of a lithium

>>
>> pack is a
>>
>>>good idea, as it automatically balances the back, which should be

>>
>> done after
>>
>>>every 3rd to 5th charge anyway.
>>>
>>>
>>>-Tapio-

>>
>>
>>


 


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