What causes a Lipo cell to puff up?

[iamdarkyoshi]

I have two 17W/hr lipos in a battery bank made for three 18650s. It has an awesome battery life, cells measured over 8.5Ah. But these are lipos, not cylindrical cells. 

 

I got these two lipos from a 3 cell battery pack where one of the cells bloated. I kept the two other cells, and they have been working fine, but what caused the third cell to bloat up when it was a laptop battery? Overcharging? Overdischarging? Heat?

[Windows7ge]

I believe it's due to the electrolytic fluid drying out and the battery starts to run hotter causing it to expand. Could be wrong. I'm not a battery expert.

[spartaman64]

dispose of the bloated lipo in a safe way immediately and dont use it. it is obviously damaged somehow and could blow up. in fact i recommend not picking it up with your hands

a lot of things can cause this like moisture, heat, physical force

[iamdarkyoshi]

2 minutes ago, spartaman64 said:

dispose of the bloated lipo immediately and dont use it. it is obviously damaged somehow and could blow up

Yup. That is what I did. I kept the two cells that were not bloated.

[Naeaes]

Just in case you and/or someone reading this didn't know, Lithium (the magic metal in Lipo batteries) catches fire and explodes in contact with water. Lithium is very volatile. The moisture in the air can be enough to set it off. Damage the cell and it'll literally explode on your face. Do not mess with broken down batteries unless you absolutely know what you're doing. https://www.youtube.com/watch?v=8ypUVpwgcAA

[You_are_a_cunt]

Angry pixies

[iamdarkyoshi]

1 minute ago, Naeaes said:

Just in case you and/or someone reading this didn't know, Lithium (the magic metal in Lipo batteries) catches fire and explodes in contact with water. Lithium is very volatile. The moisture in the air can be enough to set it off. Damage the cell and it'll literally explode on your face. Do not mess with broken down batteries unless you absolutely know what you're doing. https://www.youtube.com/watch?v=8ypUVpwgcAA

I do absolutely know what I am doing. I have the required safety to work with these, and when I get bloated laptop packs in, they go in a fireproof case and brought to the recycling center.

 

Even though flames are fun

[aisle9]

Excessive heat, usually. I'd very carefully (as in, using thick rubber gloves that you know are dry) remove it from the premises, as a ruptured lithium battery can catch fire.

[byalexandr]

3 minutes ago, revsilverspine said:

Angry pixies

AvE

[iamdarkyoshi]

Although not an excuse tp be careless, these cells are not quite as dangerous as the media thinks.

 

[You_are_a_cunt]

1 minute ago, byalexandr said:

AvE

indeed

[iamdarkyoshi]

1 minute ago, byalexandr said:

AvE

Lithium batteries are pretty damn skookum but they can release the angry pixies if you put their dick in a vice.

[Hackentosher]

I know that over discharge of a cell can cause damage, or discharging too quickly as shown by the slight puffing of a 35c 4s pack I have after pulling upwards of 120 amps for a maximum of 20 seconds (punch outs with an fpv quad are fun ) 

 

[iamdarkyoshi]

28 minutes ago, Hackentosher said:

I know that over discharge of a cell can cause damage, or discharging too quickly as shown by the slight puffing of a 35c 4s pack I have after pulling upwards of 120 amps for a maximum of 20 seconds (punch outs with an fpv quad are fun ) 

 

The heat in the engine bay of my dads car has damaged his lithium battery... its a bit bigger. Not alarmingly large... yet. Good thing its in a steel case.

[Hackentosher]

43 minutes ago, iamdarkyoshi said:

The heat in the engine bay of my dads car has damaged his lithium battery... its a bit bigger. Not alarmingly large... yet. Good thing its in a steel case.

LiPo's are made of witch craft and lithium. Isn't that all we need to know? And that under no circumstance do you fuck with a lipo? 

[Huntsman]

I believe that it's a faulty cell. In battery packs like these they are balance charged. If one cell is faulty or has lower capacity, logic of balance charging is to discharge the battery which voltage is higher than the rest to balance out the charging. Thus, it probably gets charged and discharged more often that others and that causes it to expand. Worn LiPos are usually plump. It's just the chemistry woodoo inside as they age.

[iamdarkyoshi]

22 hours ago, Hackentosher said:

LiPo's are made of witch craft and lithium