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Old Jun 21, 2012, 12:26 AM
I need a bigger shed..
sammyc's Avatar
Australia, TAS, Launceston
Joined Nov 2011
1,498 Posts
Quote:
Originally Posted by REVOJohn View Post
Do remember IR is relative to the battery state of charge.
Eg: A good 5000mAhr 60C cell should be about 1 - 2mohn (on cell level)
130mohm is huge. I2R during your flight is allot of heat
Professional IR machines and hald held units can be bought but they cost a fair bit more than a toy grade device
Im assuming they aren't actually 130mohm, as they are still not that old, have been looked after and stored correctly, and don't heat up much at all in use.
So I spose my meter is wrong, it would be good for comparing between batteries though.
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Old Jun 21, 2012, 06:42 PM
Quadraholic
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Beverly Hills, Florida
Joined Nov 2006
2,072 Posts
Battery storage?

After hearing all the horror stories about batteries catching fire and buning houses down, I bought an ammo can at the surplus store, and now keep them in there on the garage floor.
The question is,,, if one of them goes off in the can, will it keep on burning and set the rest off also, or will it go out do to lack of oxygen?
G.
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Old Jun 21, 2012, 08:39 PM
Space Coast USA
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Space Coast
Joined Oct 2000
21,116 Posts
The thermal runaway reaction caused by a short, puncture, or overcharging does not require oxygen from the air. This reaction however generates a lot of heat which volatilizes the organic solvents in the cell which can burn if 02 is present.

The videos I have seen of intentional lipo ignitions in a firesafe container did not ignite the other packs that had been placed in the container. YMMV Separators would probably help stop the fire from igniting other packs.

The main goal of using a firesafe container is to contain the fire in the rare case that an ignition might occur. Some modelers remove the gasket so that pressure will not build up in the container. I vent all my containers with several holes in the top.

Fires are pretty rare but if one occurred, hopefully the firesafe container would prevent its spread.
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Old Jul 02, 2012, 12:24 AM
Euphoric flights
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United States, NY, Fredonia
Joined Aug 2011
527 Posts
Question: I punctured a lipo, it smells sweet. Repeated accidental shorts along with this puncture, currently the battery flies for a brief 5 mins then the LVC is triggered and the motor pulses till I land.

Also, I can't seem to solder together my individual cells. I bought some "Solder-it" Aluminum paste, it doesn't seem to be working with my standard rosin core lead solder. I am not sure if this is because I actually do require the Zinc Solder / Zinc flux or if my soldering gun(s) are not getting hot enough. I have a 75 watt gun and a 25 watt soldering pen. I have touched the ends together to get an even hotter burn. Still not sticking.

I am wondering if it is the fact that I need the zinc solder / flux or if I need a hotter temperature, in which case I have a butane soldering gun but have not tried it yet.

Can anyone help me?
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Old Jul 02, 2012, 09:07 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,116 Posts
The sweet smell is the organic electrolyte. It is hazardous to your health. Download the pdf file. MSDS.
Quote:
Quote:
SECTION 5 – HEALTH HAZARDS
Threshold
Limit Value
NA
Signs and Symptoms
of Exposure
Following cell overheating due to external source or due to improper use, electrolyte leakage or
battery container rupture may occur and release inner component/material in the environment.
Electrolyte solution contained in the battery causes ocular tissue and skin irritation. Ingestion of
electrolyte solution causes tissue damage to throat and gastro/respiratory tract. Contents of a
leaking or ruptured battery can cause respiratory tract, mucus, membrane irritation and edema.
Medical Conditions
Generally Caused by
Exposure
The materials contained in this battery may only represent a hazard if the integrity of the battery is
compromised or if the battery is physically or electrically abused. Acute exposure: Electrolyte
may irritate skin and eyes.
Routes of Entry Skin, eyes, swallowing, and inhalation
That pack should be discharged and discarded. It is a fire accident in the making.

Soldering lipo cells- Google to the rescue.
https://www.google.com/search?q=sold...ient=firefox-a

If they are Al tabs, aluminum solder is mandatory. I would prefer a 45W soldering iron. IMO, soldering guns are not good for this application.
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Old Jul 03, 2012, 03:44 PM
RC Helicopter Pilot
TheWoodCrafter's Avatar
United States, CA, Westminster
Joined Mar 2010
1,696 Posts
Quote:
Originally Posted by GreenAce92_v2 View Post
Question: I punctured a lipo, it smells sweet. Repeated accidental shorts along with this puncture, currently the battery flies for a brief 5 mins then the LVC is triggered and the motor pulses till I land.
You really need to get rid of that battery before you burn something down.
Don't try to do any repiars.
Discharge it outside.
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Old Jul 03, 2012, 08:40 PM
yakum smakum
stevo6739615's Avatar
United States, FL, Naples
Joined Jan 2012
48 Posts
Quick question from a lipo newby. Can you put a lipo back on the charger to charge the battery back up to full charge if you did not drain the battery completely flying the airplane on two very short madien flights?

thanks,

Steve S. Naples Fl
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Old Jul 03, 2012, 09:11 PM
RC Helicopter Pilot
TheWoodCrafter's Avatar
United States, CA, Westminster
Joined Mar 2010
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Quote:
Originally Posted by stevo6739615 View Post
Quick question from a lipo newby. Can you put a lipo back on the charger to charge the battery back up to full charge if you did not drain the battery completely flying the airplane on two very short madien flights?

thanks,

Steve S. Naples Fl
Yes you can.
They are not like NiCADs that develop memory.
Not a problem.
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Old Jul 03, 2012, 09:42 PM
yakum smakum
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United States, FL, Naples
Joined Jan 2012
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Thank you, Wood Crafter, I was not sure and I did not want to hurt anything.
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Old Jul 04, 2012, 09:07 AM
Space Coast USA
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Space Coast
Joined Oct 2000
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Quote:
Originally Posted by TheWoodCrafter View Post
Yes you can.
They are not like NiCADs that develop memory.
Not a problem.
Stevo, this is good info, however, do not store them fully charged. It shortens their life and decreases the C-rating. Ideal storage conditions are 3.85v/cell @ 45F.
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Old Jul 06, 2012, 08:07 AM
Registered User
Joined Jan 2008
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Originally Posted by hoppy View Post
Stevo, this is good info, however, do not store them fully charged. It shortens their life and decreases the C-rating. Ideal storage conditions are 3.85v/cell @ 45F.
I've been reading for a while now and what is the general rule for how long a pack can sustain being fully charged before it should be placed into a storage voltage condition?

I currently have started back into RC Airplanes and going electric this time. My plane is almost ready but now to the point... I have purchased some Turnigy 3.3A (3S) and 2.2A (4S) Lipo's (both 30C discharge rate). I've charged them up to full capacity and they have been that way for about a week now. I don't plan to use them for at least another 7 days.

Should I place them at the storage voltage or will they be fine staying at the full pack voltage?

And you know, it's impossible for me to find any information about Turnigy packs. Couldn't find a manufacturer's website, specs on recommended charge or discharge (for charger) rates to optimize battery life. Right now I'm discharging at .7A and charging at 1.5A as I'm not in a hurry.

Thanks for any advice.
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Old Jul 06, 2012, 09:18 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,116 Posts
It's thought that the time at full charge is cumulative so the fewer days kept at full charge the better.
Personally, I'll accept anything under 3.95v/cell for short term storage. The other factor is temperature. The higher the temperature the greater the harm to the packs at full charge. Leaving packs fully charged in a 100F garage is really bad. All of my Turnigy packs have puffed a bit from my carelessness in that regard.

The ideal storage condition is 50% at 45F.

Check this article out.
Look at how fast a Lipo battery degrades at 100%charge @40C (104F) - It lost 35% of it's capacity in 3 months.
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Old Jul 11, 2012, 05:44 PM
Suspended Account
United States, TX, Austin
Joined Jun 2012
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Why the HELL are they using aluminum as the tabs for cells?
Aluminum's not the best conductor!
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Old Jul 12, 2012, 05:43 AM
REVOJohn's Avatar
Singapore, Singapore
Joined Apr 2012
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Originally Posted by Just4parts View Post
Why the HELL are they using aluminum as the tabs for cells?
Aluminum's not the best conductor!
one is Al and the other Ni due to their internal connections to the cell anodes and cathodes BUT....they should nickel tab them when they come out of the cell
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Old Jul 12, 2012, 08:45 AM
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United States, TX, Austin
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Good English.
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