the RC (radio control) and electric rideables thread

testing lipo battery safety devices - "batbox", regular lipo bags, and of course a control test with no protection. nice high-speed footage. bonus = transparent large scale 3d printed p51 mustang!


i think i'll order a lipo bag now. granted, when my batteries start to puff or degrade, i charge them at very low rates (well below 1C) and i stay at my desk, next to the charger. of course i don't have any huge batteries (biggest ones are 3s 1500mah and they take an hour at 1C) so that's feasible.
 
^ I enjoy watching those guys.

i personally store all my LiPo batteries in a SentrySafe fire proof box and charge them/transport them in LiPo safe bags. you can find those bags that can fit the exact dimensions of your batteries instead of the "envelope" style bags. i really dislike the envelope style bags because I've gotten fiberglass splinters all over my hands from pulling the batteries out after a charge.
 
I recently read a paper on a study into the lipo batteries, and it seem like the reason they become unstable are some structures appearing in them that can grow and in the end lead to a run amok situation.
Sadly i have not been able to find the paper / study for you guys to read.

I charge my lipo batteries in a stainless steel pot in my window sill, and i store them i my oven in the kitchen as i dont use it for its intended purpose.
And off course i dont leave a charging lipo, if i have to go to the toilet i activate a fire detector i have just for this situation.
 
i was thinking of getting this one to store all my batts in: https://www.amazon.com/gp/B01D88ICDMand maybe this small one to use while charging: https://www.amazon.com/gp/B01IMM6RBI
good to know about the envelope ones giving you fiberglass splinters. it's bad enough accidentally touching my quadcopter where the carbon fiber is splintered from crashes.

i already wrap a temp probe around the batteries while charging (except the little 1s batteries for our micro quads) so that supposedly the charger will shut off if it gets too hot, but a bag/box is cheap insurance.

the sentry safe seems similar to the batbox they showed. only thing is, the sentry safe is designed to protect from fire that's on the outside of the box, not the inside. wonder if that makes any difference...

one big discussion in the yt comments was about people using ammo boxes to store and/or charge batteries. consensus seems to be that ammo boxes (unmodified) are a bad idea because they're sealed and will blow up if a battery ignites inside. if you drill holes in the top and line with fireproof cloth that will let it vent the smoke/pressure without blowing up at least.

someone else suggested storing a ziploc bag of sand in a storage ammo box on top of the batteries so that if they decide to ignite, the bag will melt and dump the sand onto the batteries, automatically putting it out. not a bad idea IMHO.

right now i store my batteries in a foam-lined plastic box i got off banggood for like $1 - meant for storing flashlights, so it has a sticker on top touting certain "features"... so either the box or its contents are supposedly:
  • Power Light
  • Energy Saving
  • Waterproof
  • Explosion Proof
  • 800M effective radiation distance
:rolleyes:
 
Wow !
Look , so many reasons lipo packs flame , and number one would be imbalance ...
I don't have time top get into it right now .. But latter I might try explaining why lipo batteries flame out .
And how to monitor your batteries ..
 
old4570 said:
Wow !
Look , so many reasons lipo packs flame , and number one would be imbalance ...
I don't have time top get into it right now .. But latter I might try explaining why lipo batteries flame out .
And how to monitor your batteries ..
Click to expand...
yeah flite test talked about that in an older video:

i can't even fathom NOT using a balance charger. it's the only way i ever charge anything.

edit: originally put wrong video
 
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I preach Li safety but I don't follow it very well :rolleyes: Drilling small holes isn't enough. When a Li cell vents it is almost a low-velocity explosion of gasses being generated and it takes lots of large holes to prevent pressure-bursting of the container. An ammo can should do OK with all the gasketing material removed. The 'bag of sand' is a good idea too, While it wont stop the fire, it will help contain any sparks being emitted and sink away some of the heat more safely.

The worst risk with these is not the fire but the gasses being generated. Hydrogen Fluoride will be present and even a very small quantity if that in your lungs can be deadly or worse. As a liquid it is almost instantly trans-dermal and again only a very small quantity can do you massive harm. You'll notice the visible effects of the skin burns, but the chemical effects to the internal organs from liquid or the gasses may not appear for as much as 24 hours later. Immediate treatment is mandatory so if you get exposed to this stuff get medical help immediately without delay.

A comprehensive discourse on LiIon cell safety can be found here: http://budgetlightforum.com/node/45314 A few vids are available on DBSAR's YouTube channel https://www.youtube.com/channel/UCXC0vlJlzc_7LMlIL9mz5tw where he intentionally causes cells to vent. Li batteries are generally safe if treated correctly but things can rapidly become very dangerous with them so you need to exercise due care with them and respect the severity of the danger ;)

Phil
 
Ok , when they started talking about 3 volts I kind of got a little P****D

Look , each pack is made up of cells , the problem is - How well are these cells matched !
Some companies go to some effort to match the cells and some companies go to no effort to match the cells in the pack ..

The things that affect MATCHING , Discharge capability , the storage capacity , and cell quality .
As we all know , in manufacturing there is VARIANCE ! , So if a pack is made up of batteries from either extreme end of that variance , you may have imbalance .
Have I confused anyone ..

Here is an example ..
Cell one has an internal storage capacity of 1200mAh , and a discharge capability of 20Amps
Cell two has a internal storage capacity of 1100mAh , and a discharge capability of 25Amps
Does anyone see a problem ?

Now if we put these batteries together into a 2 cells pack ( 2s ) and lets say its a budget pack with a 1500mAh label on it ( very common ) .
Now under gentle discharge , lets say one amp . Both batteries may discharge well until around 3.5v or 3.6v .
The battery with less capacity , is going to start dropping voltage faster than the battery with more capacity ..
So by the time the better battery is at say 3v the battery with less capacity might be 2.5v .

Just let me say that over discharging Li-ion is BAD ! ( OK )

Now , under high load !
The battery that is capable of higher discharge and has a lower internal capacity is :

1) Discharge faster than the other battery
2) Going to deplete faster
3) Voltage will drop faster
4) Under high load there is a lot of voltage sag , so by the time ( under load ) one battery is say 3.3v the other might be 2.5v or lower under load ..

Am I explaining this well ?
The more cells you have in a pack , the more chance of FLAME CITY .

This is why I test my packs to see at what point the imbalance kicks in .
I have found 3.5v is the voltage region that most of my packs ( cheap ) develop imbalance ...
If you wait for 3v ( 6v for 2s - 9v for 3s ) then you may have waited too long .

Hence I use a battery monitor/alarm attached to my pack set to around 3.3 - 3.5v ...
Which ever cell reaches said voltage first triggers the alarm .


So monitor your batteries - Each cell ..
Check them after ( balance ) charging , check them after use and before charging - Be aware of what your battery is doing .
For a few $$ you can buy a battery voltage monitor / alarm .

It's this imbalance in the pack that causes FLAMES ...
And the inability of users to monitor such .

Packs can flame under HEAVY use , they can flame when charged FAST ..
I dont charge big packs with more than 1 Amp , yes it takes a while but I like to take care of my batteries .
I also balance charge , because if there is a bad / weak cell , you dont want to create imbalance whilst charging ..

A) You need to be aware of your batteries and use them accordingly .


Now there is a lot more to this stuff and so many experts its just not funny !
I am not an expert , but I do experiment and monitor my batteries and try and have some idea of what is going on .
I have been playing with Li-ion for about a decade now , so I think I have some understanding of the why and where and when .
And understanding why lipo packs flame is some what important .
 
so what's the proper way to dispose of a bad one? i've never found any sort of consensus. some say dunk em in salt water to short/discharge completely then chunk in the trash, some say discharge as much as possible w/ battery charger/discharger then cut off main leads and twist them together to kill the rest of the juice (uh, no thanks)...

i have two 3s 1000mah batteries i don't need anymore. one is puffed, and the other i suspect one of the 4 conductors for the balance lead has come off the little safety board inside, as only 2 cells report any voltage - my battery charger/discharger won't do anything with it because it says they're too far imbalanced - failsafe built into the charger firmware. the puffed one i discharged at 0.3a down to a total of 9vdc (3.0v/cell), and i'm ready to get rid of it. but where? i don't want to just chuck it in the trash and have it blow up in the back of the garbage truck, esp when they crush it.

i guess since the batteries are junk it won't matter if i take off the outer shrink wrap of the second one (not puffed) and see if i can repair the balance wiring to safely discharge it...

of course, even a "dead" lipo still has plenty of juice in it. how do i get rid of the rest of the charge safely? and where to properly dispose of them? do hobby shops accept used lipos the same way auto parts stores accept used car batteries?
 
good stuff @old4570 - i have my low battery alarms set to 3.4v as well, so that when they bounce back, they're right around storage voltage of 3.7v/cell. only time i've ever run them lower than that is when it was time to get rid of a battery (as above). and yeah the alarms are cheap. i bought a 5-pack of them for like $6 with free shipping a year or 2 ago. so i can afford to lose one in a crash or something. the first one i ever got quit saving the trigger voltage (it kept resetting itself to something stupid like 2.5v) so i removed the piezo buzzers and now i just use it to silently check the charge on my batteries.
 
I use a lipo buzzer for when i run my G-scale train with the 5 S battery, the hobbyking one i have are insane loud, so no problem hearing even if train is out in the garden and we are inside at my friends house.

I get rid of my old lipos at the recycling place, where you can ditch everything from the leaves on your lawn to old refrigerators and other electronic gear.

Those places are now haunted by eastern gangs as much of what Danes throw out actually still work, so they steal old TV and computer stuff and refrigerators at those places and ship them east.
 
Gibson99 said:
so what's the proper way to dispose of a bad one? i've never found any sort of consensus. some say dunk em in salt water to short/discharge completely then chunk in the trash, some say discharge as much as possible w/ battery charger/discharger then cut off main leads and twist them together to kill the rest of the juice (uh, no thanks)...

i have two 3s 1000mah batteries i don't need anymore. one is puffed, and the other i suspect one of the 4 conductors for the balance lead has come off the little safety board inside, as only 2 cells report any voltage - my battery charger/discharger won't do anything with it because it says they're too far imbalanced - failsafe built into the charger firmware. the puffed one i discharged at 0.3a down to a total of 9vdc (3.0v/cell), and i'm ready to get rid of it. but where? i don't want to just chuck it in the trash and have it blow up in the back of the garbage truck, esp when they crush it.

i guess since the batteries are junk it won't matter if i take off the outer shrink wrap of the second one (not puffed) and see if i can repair the balance wiring to safely discharge it...

of course, even a "dead" lipo still has plenty of juice in it. how do i get rid of the rest of the charge safely? and where to properly dispose of them? do hobby shops accept used lipos the same way auto parts stores accept used car batteries?
Click to expand...

I discharge them , slowly .. Then if you want you can plug them into something that might drain them more or use your charger and discharge them to a lower voltage ..
So lets say a 3s - 9v empty , you might discharge it to 8v ..

if you want to keep the connector , then cut it off . I do tape mine so as to stop them from shorting .. But a lot of people throw the discharged battery into a bucket of water so as to ( kill it I guess - relatively safely )
I don't know of any place that collects LIPO , do they recycle lipo ? , I do know that that some places collect lap top battery packs - but the batteries themselves ? I think they go to land fill .
And they just put new batteries in the pack - replace the bad one/s and sell as refurbished ..

So discharge the battery , throw it in a bucket of water if you want , tape it up so it wont short .
When the battery is empty , there is little chance of flame .. Virtually no chance .
 
old4570 said:
I discharge them , slowly .. Then if you want you can plug them into something that might drain them more or use your charger and discharge them to a lower voltage ..
So lets say a 3s - 9v empty , you might discharge it to 8v ..

if you want to keep the connector , then cut it off . I do tape mine so as to stop them from shorting .. But a lot of people throw the discharged battery into a bucket of water so as to ( kill it I guess - relatively safely )
I don't know of any place that collects LIPO , do they recycle lipo ? , I do know that that some places collect lap top battery packs - but the batteries themselves ? I think they go to land fill .
And they just put new batteries in the pack - replace the bad one/s and sell as refurbished ..

So discharge the battery , throw it in a bucket of water if you want , tape it up so it wont short .
When the battery is empty , there is little chance of flame .. Virtually no chance .
Click to expand...
my charger doesn't let me configure the end voltage for the discharge cycle - it's an eachine WT50, and lipo discharge is fixed at 3.0v/cell.

i don't know if lipo can be recycled either. i know lead-acid can, and apparently alkaline as well. dunno about other chemistries.

just peeled the cover off the 3s that's only showing voltage on 2 cells. if anyone cares, it's a Floureon pack i got from amazon. connections look solid, and there's no safety board inside (unless there's one inside each cell) - looks like the balance and discharge leads are soldered directly to each cell's tabs. meter shows 3.92, 3.85 and 0.00, so i guess one cell really is completely flat. i don't want to use the charger's nicad/nimh/pb discharge cycle as that uses the main discharge lead of the battery. maybe since it's cell 3 that's bad, i could lie to the charger and say it's a 2s and discharge that way, at something low like 0.3a.

if that doesn't work, i may try the bucket of water thing tomorrow, outside, to see if that will discharge the other 2 cells. even though it's already 7pm here it's dark out because we just swtiched from daylight savings (which i hate switching - just pick one, preferably whichever one it is during summer and stay there. /rant). plus if something does go south, i'd rather do it when the kids are at school - don't need them getting all wound up right before bedtime.
 
I dont use the lipo cycle to discharge for disposal , is it PB that lets you set the voltage you want ?
If you wanted you could disassemble the pack , 3 individual cells ..
Then discharge them as 1s .... ( I dont think it would be safe to discharge with a dead cell there 3s )

Or rebuild the pack as 2s
 
old4570 said:
Or rebuild the pack as 2s
Click to expand...
hey that's a great idea! i was about to say i don't need any 2s packs that small, but then i remembered that my fpv headset (eachine vr008) uses a 2s pack and this pack already has a JST connector. I wouldn't even care that it has a 4-pin balance plug on it - i'd just remove the extra pin/wire. the charger won't care. and this would be a little smaller/lighter than the 1500mah 2s pack i use right now.

edit: well, scracth that. pulled the rest of the tape off and tried to separate the cells, but they used some reall good glue that's threatening to rip open the foil pouches. plus as i was gently tugging them apart, i could hear air moving thru some pinholes or something. i sure as hell don't want that anywhere near my head or even a shirt pocket while i'm concentrating on flying FPV!

so i just cut off the connectors and will be drowning it (and its fluffy twin brother) in a bucket tomorrow.
 
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old4570 said:
Or rebuild the pack as 2s
Click to expand...

yup. turned a 5S battery to a 4S after seeing a puffed cell. replacement balance plugs are affordable enough to make the effort worth it.
 
abarth said:
yup. turned a 5S battery to a 4S after seeing a puffed cell. replacement balance plugs are affordable enough to make the effort worth it.
Click to expand...
i don't see the need to switch the balance plug unless your device uses the balance plug as its power source (i have seen this in some little 2s rc cars - wltoys 1:24 scale). otherwise, plugging it into a charger or balance board ought to be transparent to the charger/board.
 
hmm... most people in this thread https://www.rcgroups.com/forums/showthread.php?1678188-How-to-safely-dispose-a-lipo-battery seem to think the saltwater thing is bogus. the light bulb thing is pretty easy to do - i probably even have an auto bulb socket in my parts bin that i could connect to a jst or xt60 specifically for discharging batteries. course now that i've already cut the plugs off these 3s i'd have to solder them back on, but there's still big solder blobs on the batteries so it should be easy. perhaps i'll stick the cells down into a small bucket with some sand (to act as both heat sink and fire safety) then plug in the bulb... and leave it in the middle of the back yard for a day or so.

i guess i can see the utility in intentionally shorting the battery so it doesn't get any "rebound" charge, but i figure by the time it's below 0.1v/cell, it ought to be pretty safe and not really need to be shorted. what do you think?
 
Are you disposing of the entire pack ? Cos its not the dead cell thats the worry , but rather the ones still retaining energy .
 
Quad racing - Quad speed records !

Anyone keeping up with Quad speed attempts ?
Anyhow , these guys run onboard telemetry - so they can see how much power their quad is drawing from the battery ..

Anyways , the guys going for speed records started blowing up their batteries , ??? I thought this interesting .
Watching the onboard telemetry you could see NORTH of 120Amps ... ( This is a lot of current )

I have previously mentioned voltage sag under load , under this kind of load the voltage sag would be extreme .. ( Per Cell )

Now through my battery testing I noted a tendency for batteries that could not sustain current to Voltage Collapse ...
Can you guys guess why these batteries were flaming out ? Yeah because the weakest cell in the pack would voltage collapse , when this happens a battery can reverse polarity and rather than supply energy it pulls energy from the other batteries .
Now in a multi pack this is the same as a short , and we know what happens when we short out a lipo pack ...

So the answer was obviously to run more than one battery pack to halve current draw ..
But this sort of extreme power demand amply demonstrates how lipo packs fail and flame , even good ones .
Because as the old saying goes : A chain is as strong as its weakest link ..
I don't know how much effort goes into matching these battery packs , but I dont think anyone builds packs to 100+ Amps ( performance matched cells )
 
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