Old, unused but puffed

[trex]

I have a couple of lipos that are 3 years old but not used at all. Not charged. Not even connected to anything (except my voltmeter).

When I found them again a few days ago they were both slightly puffed. They were intended for my T-rex 450 but I am afraid of using them as they are.

I am hereby soliciting suggestions for what I should do with them. Come up with something useful (or funny)!

[Sleepyc]

Lipo's have a shelf life of around 2 - 3 years.
After that used or unused they are toast.
They will usually take a charge and then work for a few min and then DUMP hard.

I know this sucks, but I'd dispose of them outside of your house.

[Abala88]

I read somewhere that Lipos should be discharged to zero volts then soaked in a bucket of salt water for a few days. The Idea is that the salt neutralizes the battery chemistry and eliminates the risk of fire and contamination when the packs are sent to the trash.

[Sleepyc]

Yea, that is a great idea. Sorry I hope I didn't sound like i wanted him to toss them into the woods. I just meant after they have puffed I would not store or keep the packs inside the house!

[trex]

Thank you!

I was thinking more in terms of something educational. "Science" if you prefer. I do not expect them to power anything valuable. At least not something that could crash if power is lost.

For example, I could charge them and then discharge while measuring capacity. That way I could learn roughly how much capacity is lost by just storing for three years.

Also, I could mishandle them in a controlled way to learn how and when they fail. Example of mishandling could be overcharging it while logging current and voltage as well as recording the inevitable fireworks on video. Given the amount of effort I wouldn't do that unless there is a hypothesis to test or something to learn.

I know the general consesus is that puffed lipos should not be used. I do not know exacly why or what could happen to them. Can they leak or catch fire just by beeing stored?

These packs are 3S nominally 2150mAh 18C.

BTW. I do have another battery that I am still using. After 5 minutes of flying I will put back about 800mAh. That pack is not puffed but older than those that are. It's nominal capacity is 1500mAh. It is a different brand.

So my question is really: "Is there anything we'd like to learn about lipos that can be learned only if a pack or two is sacrificed?". If so, I have a couple to sacrifice.

[jones007]

I have a lot of 4-year old LiPos that are still working well, but they are used in slow-drain applications, typically 1/3C or less. They get used a few times every 2 to 3 months. I have others from the same batch that didn't get used for several years, and random cells in the packs puff badly when any significant load is applied.

The recommended disposal technique is to drain them low (not necessarily to zero, but low enough that they won't get hot if there's a short), puncture the cells (the part where you find out if you drained them enough), and then soak them overnight in salt-water. After this, they are not haz-mat, and can go into the landfill.

--Kevin

[nybbler]

Trying to charge a puffed battery is just asking for "venting with flame".

[trex]

Trying to charge a puffed battery is just asking for "venting with flame".

That's interesting. You are not the first to say things like that. On the other hand, there are people who claim they fly puffed packs with no issues (I do not suggest or recommend anyone do that).

One possible use for mye puffed lipos might be to repeatedly charge/discharge them in an orderly fashion to see if and when they will ignite.

Another idea would be to use them for testing ways to put out a lipo fire. Some claim a lipo on fire produces its own oxygen so that common firefighting techniques does not work.

Both of the above ideas would require some effort and a place where a fire would be acceptable. For that reason I would not do it unless there is something to learn. If people have already done and documented either of these things, post a link!

Have a safe day!

[aaronredbaron]

what it basically comes down to is how good your charger is and balancer technology. If you try to charge a pack with a puffed cell on a charger without a balancer, a fire is very likely. If you use a charger with a good integrated balancer, it may be able to charge the pack without over-charging the puffed cell. A puffed cell will have much less capacity than one in good shape, hence the puffed cell will peak much sooner than a cell with good ability to hold capacity. Its when the cell is over-charged a fire is likely, puffed or not. A charger without a balancer won't know one cell has already peaked if the total pack voltage is still below the peak voltage for the whole pack. Without an integrated balancer the charger will continue to pump full current into the pack even if one of the cells peaks early. Puffing leads to a severely out of balance situation, which is why a fire is likely if you are not using a charger with balancer technology. A balance charger will prevent individual cells from becoming over-charged.

[trex]

That makes sense aaronredbaron. Maybe a balancer is the difference between those who see smoke and those who don't?

I always use a balancer for charging t-rex batteries. Mainly for safety reasons. A balancer reduces the risk of fire caused by:
- defective cell(s)
- malfunctioning charger
- incorrect charger settings

I don't have an integrated balancer. I use a separate one (LBA10 from Hyperion). I don't think that should make a big difference safetywise.

BTW. Those puffed batteries are in good balance as they are now. That could change if I charged or discharged them of course.

[ericb]

If you have a decent place outside, hook them to a 12V car battery and watch the pretty flames. Otherwise it is kind of fun to shoot them with a 22.

[Sgt_Ric]

Hopefully you don't live downtown!