Puff battery question

[SidneyKi]

Today after flying my quad I notice the batter looks a little puffy.
It is a nano tech 2200mha 25-50c lipo

Is it ok to continue to use this battery?
It is still able to charge.

Will it catch fire just laying around while it is in this state?

I think I ran it too low today while flying my quad.

 

[xuzme720]

They don't burst into flame sitting. it's a little puffy and you should keep a careful eye on it while charging but it should be fine as long as you don't abuse it.

 

[OttoPilot]

Technically, Yes, you can still use it. Yes, it will take a charge. No, it won't explode 'just sitting there'.

Yeah, you can use it and everything will probably be fine it's not too puffy...

The over-conservative, safest, thing to do if you're not 100% sure about things is retire it from service.

My understanding of Li-Po battery puffiness and how it relates to failures (full disclosure, I'm not a chemist...just an engineer. If someone sees something wrong, correct me):

Lipos puff due to a buildup of gas (mostly hydrogen) that occurs when the contents (mostly lithium) in the battery breaks down due to damage (being over-discharged in this case). The envelope the lithium-polymer is stored in contains this gas and gets puffy. The puffiness of the battery is directly tied to how much of this gas has been generated and can be used as a SWAG to roughly determine how much damage it has undergone (that's why I say "It's not too puffy" above).

When too much damage occurs and too much gas is generated, the envelope can't contain it and vents controllably (if the gasses build slowly), or pops (if the gasses build too quickly). This releases the lovely flammable gas mixture. This alone will not cause a fire...just a stinky, caustic, cloud of chemicals.

If an ignition source is nearby (even a spark internal to the battery) you now have a fire (think Mini-Hindenburg). Since the gasses are pressurized inside the battery envelope and the heat from the fire causes even more gas to be generated, they can send out blowtorch like flames. Oh the humanity!

If you do decide to use it, follow all the normal battery charging precautions (you're already following these...right?):

1. DO NOT CHARGE UNATTENDED.
2. Charge in a flame proof container, away from anything combustible (I charge inside cinderblocks, on a cement floor, against a cinderblock wall).
3. DO NOT CHARGE UNATTENDED.
4. Make sure you're not overcharging/mis-charging (that should go without saying).

 

[SidneyKi]

Thanks everyone,..

 

[MVogan]

Technically, Yes, you can still use it. Yes, it will take a charge. No, it won't explode 'just sitting there'.

Yeah, you can use it and everything will probably be fine it's not too puffy...

The over-conservative, safest, thing to do if you're not 100% sure about things is retire it from service.

My understanding of Li-Po battery puffiness and how it relates to failures (full disclosure, I'm not a chemist...just an engineer. If someone sees something wrong, correct me):

Lipos puff due to a buildup of gas (mostly hydrogen) that occurs when the contents (mostly lithium) in the battery breaks down due to damage (being over-discharged in this case). The envelope the lithium-polymer is stored in contains this gas and gets puffy. The puffiness of the battery is directly tied to how much of this gas has been generated and can be used as a SWAG to roughly determine how much damage it has undergone (that's why I say "It's not too puffy" above).

When too much damage occurs and too much gas is generated, the envelope can't contain it and vents controllably (if the gasses build slowly), or pops (if the gasses build too quickly). This releases the lovely flammable gas mixture. This alone will not cause a fire...just a stinky, caustic, cloud of chemicals.

If an ignition source is nearby (even a spark internal to the battery) you now have a fire (think Mini-Hindenburg). Since the gasses are pressurized inside the battery envelope and the heat from the fire causes even more gas to be generated, they can send out blowtorch like flames. Oh the humanity!

If you do decide to use it, follow all the normal battery charging precautions (you're already following these...right?):

1. DO NOT CHARGE UNATTENDED.
2. Charge in a flame proof container, away from anything combustible (I charge inside cinderblocks, on a cement floor, against a cinderblock wall).
3. DO NOT CHARGE UNATTENDED.
4. Make sure you're not overcharging/mis-charging (that should go without saying).

Another good reason to retire any puffy LiPo battery is that the damage has changed the battery's abilities which can make it both unreliable and dangerous.
That C-rating of 20C or 40C represents the ridiculous current these things can safely give us. LiPos have a really low internal resistance.
C=Capacity. 20C of a 2200mAH cell means it will give 44 amps! ... but not after it is puffy.
Internal resistance has increased. Now it is only capable of, say, 5C. When you try to pull 10C out of it, the damaged part is now acting as a resistor. Resistors get hot when you run high current through them. When batteries get too hot they explode.

Furthermore, damaged cells can ignite just sitting on the shelf. They should be disposed of in accordance with local regulations.

If it vents gases without explosion or fire, it is still going to cause a lot of damage. The gases that come out will ruin everything they touch. I saw our bridgeport mill go completely rusted overnight in the presence of a vented battery. We cleaned it up and it was fine, but we lost a lot of computer hardware to the corrosion these cells can cause.

Respect your batteries! I worked in batteries for 9yrs. The energy density inside LiPos is about 2/3 that of TNT. Powerful stuff! It is cool because it will pull your plane vertically, but you must respect these things.

I second OttoPilot's charging recommendations quoted above.
MVogan

 

[nerdnic]

This is probably the most informative thread I've read about puffy batteries. Thanks for the explanation guys.

 

[abieex]

I would probably use it but with EXTREME care and caution. I would not let it inside my shop or home.