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Topic Review (Newest First)
01-11-2016 03:54 PM
Ditchrunner Stanford boffins snuff out li-ion batt blaze risk • The Register

If this comes to market it will resolve most of these issues. No help for now of course.

The explosive side effects of overheated lithium-ion batteries have long been documented, and have caused everything from groin burns to the suspension of Boeing 787 flights.

Now boffins at Stanford think they have the answer.

If the electrolyte within a battery reaches 300 degrees Fahrenheit (150 degrees Celsius) then it can catch fire, and for years battery manufacturers have been trying to build in a safety system to stop this happening. While techniques have been developed to shut down a battery that overheats, it comes at a cost.

"Unfortunately, these techniques are irreversible, so the battery is no longer functional after it overheats," said Stanford engineer Yi Cui, who invented just such a system. "Clearly, in spite of the many efforts made thus far, battery safety remains an important concern and requires a new approach."

Cui and a team led by Zhenan Bao, a professor of chemical engineering at Stanford, have now built a solution – a polyethylene film studded with nickel that covers the battery's electrodes.

The nickel spikes conduct electricity, but if the temperature rises the polyethylene expands and breaks the electrical connection, then shrinks to reestablish the electrical flow as it cools.

"We can even tune the temperature higher or lower depending on how many particles we put in or what type of polymer materials we choose," said Bao. "For example, we might want the battery to shut down at 50 C or 100 C."

The technique is not only reversible, but repeatable. The team applied a heat gun to the substance to activate the tiny circuit breakers, let it cool to reestablish power, and repeated the process many times.

"Compared with previous approaches, our design provides a reliable, fast, reversible strategy that can achieve both high battery performance and improved safety," Cui said. "This strategy holds great promise for practical battery applications."
01-11-2016 02:42 PM
CDA 455
Quote:
Originally Posted by XtremeJ View Post
Thanks to the folks who have posted good info in this thread.
Indeed.


Having this important safety info in one thread will definitely help reduce the chances of one of us having an 'IED' moment !
01-11-2016 02:36 PM
makya
Quote:
Originally Posted by bgaidan View Post
Oh, I can get them online all day long. I just don't like paying $20+ per can when you can usually get them for $8.

I'm thinking I may have a metal toolbox that would fit the bill until I'm somewhere where I can find a good surplus store again.

I don't like the idea of storing all of them in the same box either. If one goes, I lose $300 worth of lipos.
If you have the room to, you can store them safely a few inches from one another without the fire spreading.
01-11-2016 02:27 PM
bgaidan
Quote:
Originally Posted by makya View Post
you can also just use a cash box, like the ones they sell at walmart.
they also carry ammo cans at walmart: Blackhawk Ammo Can, 30 Caliber - Walmart.com
Oh, I can get them online all day long. I just don't like paying $20+ per can when you can usually get them for $8.

I'm thinking I may have a metal toolbox that would fit the bill until I'm somewhere where I can find a good surplus store again.

I don't like the idea of storing all of them in the same box either. If one goes, I lose $300 worth of lipos.
01-11-2016 02:24 PM
makya
Quote:
Originally Posted by bgaidan View Post
I really need to find some ammo cans...nobody seems to sell them locally. Especially now that I just got about a dozen 3 and 4s lipos from 3DR's clearance sale and I have several on the bench that are a little puffy.

I had an 1800 3s drop to 6v on me this weekend. It's been puffed up for a while and I just kept it around to power stuff on the ground if needed. After seeing it go that low, I salvage the power lead off of it and then threw it on the driveway, repeatedly...trying to make it go critical. Even hit it with a hammer a couple times. Never did anything.

I have a couple more 6000 3s in the mail, which will bring me up to about 20 total in the 3000 - 6000mAh range each.


I have another 3000 3s that I was using to power my vid tx while I was trying to set it up on the bench. It wasn't charged very much when I started using it and I forgot how long I had it plugged in, but it's dropped pretty low too...about 2.8v per cell. Not puffy though. I may try to restore that one...in the middle of the driveway with an extension cord!
you can also just use a cash box, like the ones they sell at walmart.
they also carry ammo cans at walmart: Blackhawk Ammo Can, 30 Caliber - Walmart.com
01-11-2016 01:31 PM
87manche
Quote:
Originally Posted by XtremeJ View Post
Thanks

swell is slight, and the battery is firm to the touch.

Part of me wants to put it on a charger and run current into it until it explodes and burns down the entire state. The other (cheap bastard) part of me wants to just get as many cycles as I can before it is toast
keep an eye on battery temps. If the pack is getting older it may be losing the ability to discharge hard, so when you abuse it doing multiple full throttle runs it heats up internally.

That's a function of each cells internal resistance.
That's also why cells can discharge at different rates and you need to balance charge the pack. It's all realted to internal resistance.

The higher quality packs are all matched cells, so they discarge more evenly.
Shitty packs are not, so one cell with higher resistance may not keep up with the other cells.
01-11-2016 01:15 PM
bgaidan I really need to find some ammo cans...nobody seems to sell them locally. Especially now that I just got about a dozen 3 and 4s lipos from 3DR's clearance sale and I have several on the bench that are a little puffy.

I had an 1800 3s drop to 6v on me this weekend. It's been puffed up for a while and I just kept it around to power stuff on the ground if needed. After seeing it go that low, I salvage the power lead off of it and then threw it on the driveway, repeatedly...trying to make it go critical. Even hit it with a hammer a couple times. Never did anything.

I have a couple more 6000 3s in the mail, which will bring me up to about 20 total in the 3000 - 6000mAh range each.


I have another 3000 3s that I was using to power my vid tx while I was trying to set it up on the bench. It wasn't charged very much when I started using it and I forgot how long I had it plugged in, but it's dropped pretty low too...about 2.8v per cell. Not puffy though. I may try to restore that one...in the middle of the driveway with an extension cord!
01-11-2016 01:03 PM
XtremeJ
Quote:
Originally Posted by 87manche View Post
some swell is normal over the life of a pack.
It should still be firm to the touch.

When it feels like it's a balloon, then it's puffed to the point of being dangerous.

just make sure that you don't latch the ammo box, or at least drill some good sized holes in the top to let it vent if one goes wrong.
Thanks

swell is slight, and the battery is firm to the touch.

Part of me wants to put it on a charger and run current into it until it explodes and burns down the entire state. The other (cheap bastard) part of me wants to just get as many cycles as I can before it is toast
01-11-2016 12:58 PM
87manche
Quote:
Originally Posted by Alpine4x4 View Post
Be smart about it and educate yourself and it's not an issue.
that's the problem though.

You don't know what you don't know.

and no one reads the page of text about battery safety.
01-11-2016 12:50 PM
Alpine4x4
Quote:
Originally Posted by DWT View Post
Nope, I don't recommend "bump starting" a lipo either but fuggit, I had to try it.


Edit:

As far as skateboard park running my exo is a fawking blast! There is a park in a podunk town near me with a bad ass park that has a 10' tube you can do loops in or drive over. It's a riot but hard on parts.
I had a couple 3s packs that were puffing pretty bad. Lost a cell on one, bumped it with the nimh setting and brought it back for a few more runs

I run the el cheapo turnigys, never an issue. Charge balanced on 2c. Dicharge/charge to storage voltage when not in use. Store in ammo can. Charge in lipo bag.

Be smart about it and educate yourself and it's not an issue.
01-11-2016 12:35 PM
87manche some swell is normal over the life of a pack.
It should still be firm to the touch.

When it feels like it's a balloon, then it's puffed to the point of being dangerous.

just make sure that you don't latch the ammo box, or at least drill some good sized holes in the top to let it vent if one goes wrong.
01-11-2016 12:27 PM
XtremeJ Thanks to the folks who have posted good info in this thread.

I have a small quad which uses Battery LiPo, 1200mAh 2-Cell/2S 7.4V 25C, JST Connector batteries. I only use the factory charger w/ balancer. After reading the Lance RV thread, and noticing one of the batteries showing a slight (very slight) bulge I figure I might as well be safe than sorry.

Charging in an ammo box now which has a cord on the handle so I can remove it outdoors when / if it catches fire.

Just how bad must a battery swell before it is fatally bad?

I took pics but the bulging is so slight I cannot tell which is a good battery and which is the bad one in the pics.
01-11-2016 11:54 AM
87manche
Quote:
Originally Posted by DWT View Post
I've used the nihm setting on my $30 chicom charger to bring back a dead lipo. If it's too low of voltage the charger won't recognize it. 15 seconds on nimh and it'll bring it back.


I have 2 pit bull dogs so I obviously live in fear that they will attack me in my sleep while my chicom lipos burn the house down around me.
I advised my brother to do the same.

and I told him to make sure that shit was at least 20 feet from his RV and to do it only until the pack voltage came up for the charger to see it, and that it was probably going to burst into flames.

You can do stupid shit, just be aware that you are literally playing with fire.

I liked the "it's just like a cup of gasoline" analogy.
01-11-2016 11:41 AM
87manche Turnigy Lipo Bunker - Lipoly Safety Charge Box

$22.
It's a pre-vented stainless ammo can.
01-05-2016 07:28 PM
CDA 455
Quote:
Originally Posted by DWT View Post
Yup a guy on rc-crawler had a lipo go bad while in an ammo can full of lipos and all it did was discolor the paint on the outside and melt the hard case of the battery next to it. His house didn't burn down and the bus full of orphans driving in front of his house survived just fine.
So there you go .
01-05-2016 06:32 PM
DWT
Quote:
Originally Posted by bgaidan View Post
Ammo cans are more than enough to contain the potential fire. No need to go crazy with a fireproof "safe". These fires burn hot and fast. If they don't have any other fuel to keep them going, they're done in a minute or two. An ammo can has no problem containing that.
Yup a guy on rc-crawler had a lipo go bad while in an ammo can full of lipos and all it did was discolor the paint on the outside and melt the hard case of the battery next to it. His house didn't burn down and the bus full of orphans driving in front of his house survived just fine.
01-05-2016 06:00 PM
y2kmxz
Quote:
Originally Posted by bgaidan View Post
Ammo cans are more than enough to contain the potential fire. No need to go crazy with a fireproof "safe". These fires burn hot and fast. If they don't have any other fuel to keep them going, they're done in a minute or two. An ammo can has no problem containing that.
I've got a small ammo can that I will try. I found a couple of the fire resistant document safes on Amazon for less than $20.
01-05-2016 05:23 PM
bgaidan Ammo cans are more than enough to contain the potential fire. No need to go crazy with a fireproof "safe". These fires burn hot and fast. If they don't have any other fuel to keep them going, they're done in a minute or two. An ammo can has no problem containing that.
01-05-2016 03:54 PM
CDA 455
Quote:
Originally Posted by y2kmxz View Post
I just got back into RC's about 2 years ago with my son. I've been charging the Lipo's in the garage on the work bench. On the way home tonight I stopped at the local hobby shop and purchased a lipo charging bag. Going to set up an area for Lipo storage and charging, and will be getting a fire proof document box or equivalent for transporting. It might be excessive, but what happened to the Clifford family and the info provided in these posts has convinced me to take the extra steps.
Your plan sounds appropriate to me.


Not excessive at all.
01-05-2016 03:38 PM
y2kmxz I just got back into RC's about 2 years ago with my son. I've been charging the Lipo's in the garage on the work bench. On the way home tonight I stopped at the local hobby shop and purchased a lipo charging bag. Going to set up an area for Lipo storage and charging, and will be getting a fire proof document box or equivalent for transporting. It might be excessive, but what happened to the Clifford family and the info provided in these posts has convinced me to take the extra steps.
01-05-2016 01:43 PM
reklund5
Quote:
Originally Posted by CDA 455 View Post
Frickin' A-men to your first point.


What's the reason, with your last point ?

I hardly drive my DD any more due to commuting by bicycling and now being retired. It sits 90% of the time now.
Sorry...i was thinking about what I leave plugged in and charging and rambled a bit. Has nothing to do with LiPo batteries. Carry on!
01-05-2016 12:31 PM
DirtyComanche
Quote:
Originally Posted by spot4me View Post
they are supposedly "environmentally friendly", but lets get real and figure that they are def not 100% good for the environment.

All it takes is one person to not prepare it for the landfill by discharging it completely or tossing one in that damaged but still has juice and it could still cause a fire. Why not treat it like other batteries and take it to Lowes or Best Buy or a similar place that will take it?
Fires are good for the landfill. They burn underground and accelerate the decomposition process of materials by a factor of 1000. Okay, maybe not good.
01-05-2016 12:27 PM
Pat Charge with the proper current for the size of battery
Charge outside
Use a decent charger or one specific for the battery, make sure it is set correctly for LIPO's
If damaged watch out
01-05-2016 12:16 PM
spot4me
Quote:
Originally Posted by camo View Post
So educate us, What are the ramifications of throwing a battery in the trash ?
they are supposedly "environmentally friendly", but lets get real and figure that they are def not 100% good for the environment.

All it takes is one person to not prepare it for the landfill by discharging it completely or tossing one in that damaged but still has juice and it could still cause a fire. Why not treat it like other batteries and take it to Lowes or Best Buy or a similar place that will take it?
01-05-2016 11:50 AM
CDA 455
Quote:
Originally Posted by makya View Post
there always have been. It's the same as buying alkalines at the dollar store vs. buying top of the line energizers.

EDIT: I just realized how much I've been dominating this thread. If you guys want me to back off just tell me.

If not, a little background:
I've been in the r/c hobby since 1985, when I was 11. I started racing in 1986 and got my first sponsorship in 1989. I've built, customized and worked on r/c cars since 1991, off and on, as a side business. I raced regionally in Northern california in ROAR,NORRCA and the defunct R/C AMA circuits. To do that, I've had to learn how to maintain my vehicles, both the mechanics of them and the electronics. I have been running scalers/crawlers for the last few years, but will be getting back into racing next month.

Batteries are extremely important to that aspect, and will make or break a race. The basics are the same as running the old NiMh batteries:

You want the cells to have the same output, duration, and internal resistance. If you have one cell that is weaker than the others, it will create a bottleneck at that connection and build up heat. Build up enough heat, and it becomes unstoppable, rupturing the seal on the pack, and catching fire. I've done it with both NiMh and LiPo batteries. The difference is that the LiPo burns much hotter.
I made this thread to accumulate knowledge and experiences with LiPo batteries.


As long as you post your knowledge and/or experience, post as much as you want .

Fug everyone else !
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