[MultiHack3D]

Originally Posted by OLD PRAIRIE RED NECK

Don't sell the farm and invest it in beer coolers yet Mike, the cooling effects appear to be pretty small and short lived.

Damn! that sucks WTH! All the money I spent, radios..servos, motors.... and now you tell me this.

Some friends you are! Your all so Un-reasonable!

Now how am I going to fly my fridge?!





LOL!................

[dashpuppy]

Originally Posted by BigJohn

Well I did some ready here and on another site to understand what may have happened and come to the conclusion that it was because of a bad cell and that's why it went on the final part of the charge. I was having some trouble with the battery last season and was thinking it may be a bad cell and from what I read it couldn't take the full charge into that cell and over charge the other two cells.
Makes sense to me so that what I'm going with, bad cell. John

Now if you had that connected to a charger & used the balance connector you would have been fine, the charger would have stopped because low cell, then saved you a case & battery and anything else that got wrecked..

[michaely]

My reading of Big John's lipo meltdown is the same - bad cell plus insufficient capacity of the "blinky" to balance charge. I also wonder if a more modern charger would not have detected the problem and stopped the charge at some point.
Knowing the internal resistance of individual cells might also give you an advance notice that a cell may go bad (as well as advise on the general aging of the pack). Some of the pricey chargers give you the IR numbers and HobbyKing as a standalone digital meter that gives you individual cell IR and current charge capacity numbers.

On building a vented metal enclosure to contain lipo fire while charging..... on detailed account of such a lipo fire in a modeler's workshop/plane storage said that the rapid expansion of gases in the lipo fire ejected embers a number of feet and those embers, while they did not start a fire, caused a lot of damage to the finish of other models..... so perhaps putting some metal window screening meshing over the vent holes might be an idea; rapidly expanding gases would still be able to vent but the mesh might prevent the ejection of embers.

thanks for the information as I am still learning about lipos,

Michael

[davidmc36]

Originally Posted by michaely

...... so perhaps putting some metal window screening meshing over the vent holes might be an idea;....

That's one thing that caught my eye about the A/C battery boxes; a fine metal screen behind slanted louvers in the some of the lids.

[OLD PRAIRIE RED NECK]

Yes it appears to be a bad cell as the temp rise when on charge at a reasonable rate seems to be small.

I like to do a hand test while charging batteries several times while they charge to see if they are getting warm, much easier when they are accessible.

It sounds like the newer chargers are more idiot proof too!

Lots of learning all around, good thread!

[MultiHack3D]

Just a thought... but would not venting a box (some type of containment) be worse then not?

My reasoning, Is a battery not absolutely looking for oxygen when it decides to catch fire?

If you vent, would you not be allowing fresh air to get in and feed the flame?

Would it not be best to limit/eliminate open (fresh air)?

If its got no oxygen or at least a reduced amount it would have no choice but not burn up and smolder out faster and cause less damage?

Like if you got a few lipos charging at the same time type deal... it could save the others.

What would be good is having a metal or fire resistant compartment for each cell.. so if one lets out the magic smoke it will not take the others out with it in a blaze of glory.

I dunno... just tossing it out there.


(added)

I know the gases expand but from every fire I seen (youtube) with people trying to make them catch fire... the expansion of gasses don't look like a hard thing to contain... they are slow and take time to do there thing when they burn up. Not a violent quick explosion from my observations.

And I would be willing to bet if they had less oxygen (lipo bag) they would eat up the oxygen quick and just die out faster. Bags surprisingly do a great job for what they are IMO.

Metal is nice and strong.. but IMO opening up vents is not a good thing... maybe its just me.

[davidmc36]

Originally Posted by MultiHack3D

Just a thought... ... just tossing it out there.

Could be a good point. The battery boxes I got already have some dividers that separated the NiCd cells into smaller groups. I wonder if that is some of the reasoning behind them.

I wonder which would be the best to use for charging and the best for transport. One has the vented lid and the others have just the small vents for hoses to hook to. Maybe a flapper valve on the small vents to let out pressure but not allow any amount of air to get in.

[MultiHack3D]

Originally Posted by davidmc36

Could be a good point. The battery boxes I got already have some dividers that separated the NiCd cells into smaller groups. I wonder if that is some of the reasoning behind them.

I wonder which would be the best to use for charging and the best for transport. One has the vented lid and the others have just the small vents for hoses to hook to. Maybe a flapper valve on the small vents to let out pressure but not allow any amount of air to get in.

Yeah Id think if your cells are in each compartment your other cells would have a great chance of (making it)

Take a look at the inside of the Bigjohns case... not everything burnt up... as crazy as the battery looks... the foam is almost all there just inches away from the cells... to me that fire looks like it ran out of oxygen... and died.

IMO I think oxygen, or lack of it is the way to think.

(added)

Yeah I think your cases are the best for ither job, charging AND storage... I know they may be a bit big but, probably the best thing you can get to be safe.

I would charge them up in ther own section and even go as far as stuff some fire retardant cloth in the tops to seal them off a bit more from getting lots of air.

Then put them on a storage charge and keep them in the same case. (furthest away from the charging compartments)

[BigJohn]

I do understand about starving a fire but I have a vent hole in my ammo boxes and the lid of the box I had was closed but still not air tight. It would have been better for me if I had removed all the items from the box but I didn't. With that being said I did lose the Blinky and a couple of my battery hook ups but other items survived and I think most of the smoke was from the foam. I'm glad that I didn't have any of my other batteries sitting in the case at the time of the charge which is something I have done before. I will from this point on charge as I always do in a contained box but I will make sure they are on their own. I had a chance to use a buddies Turnigy charger that charges with the main power plugged in as well as the balance plug and I like the fact I was able to see more of what's going on with the battery. John

[OLD PRAIRIE RED NECK]

I'm pretty sure that Lipo fires are strictly chemical reactions and air has little to do with the outcome.