LiPo Safety

by Red20RC | May 17, 2014 | (28) Posted in Tips

The introduction of Lithium Polymer batteries into the R/C hobby revolutionized the way we power our models. But as Spiderman’s uncle said “With great power comes great responsibility”…

** Thank you once again to the FT community for supporting my articles. There has already been some great comments and observations so please make sure you read on past the end of the article!**

What’s brought all this on then?

A new video came up on my YouTube feed today that got me thinking. Before we go any further I’ll let you watch it and see if it gets you thinking too. (In fact, you should click out to YouTube and also read the comments that follow the video).

To be honest, I don’t care what anyone says but unless you are actually Chuck Norris then everyone would have had the same reaction – “Oh crap, oh crap, oh crap, oh crap…” and so on. What concerns me is that the person who posted this video then promotes the actions of his “Navy trained” team as exactly the right thing to do in such an emergency – stomp on the exploding LiPo and kick it around the room a bit.

Anyway, the point of this article isn’t to point fingers. I think it is probably a good time though to look at what went wrong and what we can all learn from it…

I’m assuming that you already own a few LiPo batteries so I’m not going to go into a lecture about what a LiPo is…

What can we learn about LiPo safety from the video?

There are a couple of key points in the video that made me wince. I’m kind of hoping that they had the same effect on you and this is only going to jog your memory:

1. The battery was a DJI Phantom battery that was taken in from a customer and tested at 5 volts

Depending on the model, this LiPo was anything from $29 to $179 worth of battery. It wasn’t some cheap eBay battery. Even if you think you have the best LiPo’s on earth they are still vulnerable.

The battery was “taken in from a customer” so we can assume that despite some of the comments the people in the video had little or no information about this particular battery’s history. They don’t know if it had been thrashed, bashed, or crashed.

It was “tested at 5 volts”. This means it was terribly over-discharged for a 3-cell battery. One of the later comments scares the hell out me. “…we have dealt with many and they aren’t damaged. We can usually recover them and they are fine. We have and sell a bunch of them…” Listen carefully, I’m going to put this into a blockquote so it stands out:

NEVER TRY TO REVIVE AN OVER-DISCHARGED BATTERY. NEVER BUY A REVIVED BATTERY FROM SOME IDIOT WHO THINKS HE CAN SAFELY DO IT!

I know I said I wasn’t going to point fingers but I couldn’t help myself there.

2. It was simply sitting on the table

lipo-bagGiven that we know LiPo’s can be dangerous it is never a good idea to leave them sitting around where they could get knocked, squashed, stabbed etc. etc. In the case of the video this is particularly pertinent as they knew this was an over-discharged battery that had obviously suffered some abuse and therefore may also have been damaged internally.

You can pick up LiPo safety bags easily enough online. These are great for transporting batteries to and from the field and also for charging. You can also pick up old metal “ammo” cases cheaply enough for bulk storage of batteries. I personally use a large steel “Rhino” box from Bunnings Warehouse.

3. Their first reaction was to throw it on the carpet and stomp on it

A LiPo battery fire is an out-of-control chemical reaction. Jumping up and down on it is not going to stop the reaction and in fact only spreads the “fuel” out allowing more air to come into contact with the chemical causing more flames – and possibly setting fire to your foot.

450px-KiddeBCchemIf you are going to have an area of the workshop set aside for inspecting and working on damaged (or even undamaged) cells it would be a good idea to make sure:

  • You have a concrete or tiled floor
  • You have a fire blanket available to contain the blaze
  • You have a dry chemical fire extinguisher handy to put the fire out

It’s no good playing football with the fireball whilst someone runs to another part of the building to fetch the firefighting equipment. This is especially important if you are a commercial operation who is dealing with other people’s property.

What else should we be thinking about then when it comes to LiPo safety?

I guess the only other things to remember are those things that we should be doing on a daily basis:

  • Always charge LiPo batteries in a safe area – outside or on a hard surface (concrete or tile). If it can go in a bag then all the better.
  • Never leave batteries alone whilst charging – because you never know.
  • Always use a dedicated charger – and double check the settings if it has multiple programs (I once charged a LiPo on a NiCad trickle charge)
  • Always select your power system carefully – make sure your battery can handle the amps demanded by the motor/prop. Don’t push it either, make sure you have plenty of margin for error.
  • Don’t over-discharge your batteries – use an appropriate ESC with voltage cutoff or an onboard battery monitor/alarm.
  • Do dispose of old or damaged batteries correctly – see below.

Disposing of LiPo’s safely

When your LiPo reaches the end of its life (and they don’t live forever), it is important to give it a proper send-off.

The best way is to drop them into a bucket of salty water for a couple of days. This totally kills the chemistry in the cells rendering them safe for disposal. In fact, a totally dead LiPo is safe to go in the general household waste (but please do check with local laws before you do this).

If you want to take it one step further then this is a great guide on how to render a LiPo totally inert. Thanks to Kona R/C flyers for putting the effort into producing this.

Conclusion

So where are your LiPo’s sitting right at this moment? Still waiting to be charged on the bench after today’s flying session? Tucked in beside your Tx in your flight bag?

Or are they where they should be in a fireproof safety bag?

I’ll hold my hand up and say that I have probably broken most of these rules myself in the past week alone but that video made me stop and think – and I guess for that the guys at EZDrone should be commended.

Of course, we should never lose sight of the fact that Lithium Polymer batteries are what make everything we enjoy about electric flight possible. Just be safe and keep enjoying the power!

Kfm-6-Wing

COMMENTS

galaxy engineer on May 17, 2014
Right ON!! Great article and very well written. I almost did not click on it because I thought it was just another ''Lipo safety montage'' but you brought a very inspiring bucket of proof to the table and laid it out in a way that kept a ''know-it-all'' like me reading. I am seriously mulling over some ideas to keep my lipo handling practices safer.......(a lot safer). I have a new respect for lipos thanks to your 5 star article......
THANK YOU! and I am going to connect this very valuable article to my articles.
Brett Hays
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Red20RC on May 17, 2014
Thanks! Comments like this from anyone mean a lot to me and inspire me to keep going :-)
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WombatControl on May 17, 2014
I used to believe in the bucket of salt water method, but apparently that is NOT the safe way to render a LiPo inert. The salt water can erode the contacts on a cell before it has a chance to fully discharge.

Instead, wire up the battery to a car headlight or some other source of very small power draw - let the battery run down in a safe place until it is completely discharged. Then you can dispose of it.

The salt water method probably will work most times, but the safest way is to use a headlight bulb.
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Red20RC on May 17, 2014
That is a great comment and thank you for taking the time to post it.

I have always used the bucket of water method but the linked PDF makes interesting reading and supports what you are saying.
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WhiskeyJack on May 17, 2014
Red20Rc,
Thank you for the video and the article. I printed the article off so I would have a reference when I need to dispose of a battery. Great work, thanks, WJ.
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Red20RC on May 17, 2014
Not a problem! I'm glad this article seems to be helping so many people out.

Thanks for the comment :)
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FinalGlideAus on May 17, 2014
Just a word of note that the white powder in those fire extinguishers is VERY corrosive to electronic equipment (and not good for your own health either). I would expect ALL the electronic equipment that was in that room to fail in some way in the next couple of years. That powder is extremely fine and gets EVERYWHERE. If you use a powder extinguisher then right off the stuff through insurance, otherwise use a CO2 extinguisher.
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Red20RC on May 17, 2014
That is definitely worth knowing. I'm definitely not an expert on fire extinguishers and went looking for some information that might help.
I guess dry powder is good if your house is about to burn down but it's great to know there is a better alternative out there that won't wreck your entire operation.

I once actually set off a dry powder extinguisher by accident (sort of) in our old Scout hut. The mess was incredible, it took three days to clean up afterwards!

Thanks for the comment :)
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rick_harriss on May 18, 2014
Never mind your flying kit - Just think of all the things you have in your house that contain LIPO batteries, In my case:
3 Phones, 3 Kindles, 2 tablet computers, A smoke alarm, a watch, several LED torches,

I charge them and never really think about them otherwise.
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Red20RC on May 18, 2014
Does make you think, and supports just how useful and versatile (not to mention stable) these batteries are if used properly.
Of course, SR-71's comment below highlights the key difference. Our applications have a very high current drain, and that is where the problems can occur. You don't take your iPad battery out of its case, strap it to a fast moving object and try to pull all of the power out of it in 5 minutes!
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SR-71 on May 18, 2014
Yes but those devices are extremely low discharge rate....our models are high
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InTheFade on May 19, 2014
Great article. when I first started using lipos I was pretty cautious but have become complacent over the years. I keep most my lipos in fire safe bags but after flying I would just leave them laying around. About a month ago I just looked at my lipos sitting there out in the open and pictured them bursting into flames. I went out that day and bought a heavy duty metal tool box that I now keep all my lipos in... Sometimes we all need a reminder of how dangerous these can be.
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Red20RC on May 21, 2014
You know what? Even after writing this I think I still have two 3600mah 3 cells sitting on the bench in the workshop after I used them this afternoon! (puts down laptop and goes to put them back in the box)...
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ABQ Bobcat on May 20, 2014
Great article - especially for those new to the RC community. I am currently storing my batteries incorrectly (sitting in the open and most of them have a full charge) but thanks to reading this article and doing further reading about using 'Storage' setting on my charger, I'll be a lot safer. Thanks a lot, for me and my school. I can't imagine what my classroom would look like if a LiPo went off in it!
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Red20RC on May 21, 2014
Thanks for the comment!
I'm glad that this article seems to be getting people thinking and talking.
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victour20010 on May 20, 2014
Great article! Regarding the link about "render a LiPo totally inert" (http://konarcflyers.com/Lipo-Disposal.pdf), have any of you guys performed these steps? Just curious. I have a couple of batteries that I am currently retiring and the batteries are ready for Step 8 "Remove the outer covering". Step 10 "Score the cells" kind of scares me. Have any of you guys done that? Does it create any fumes and what not?
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Red20RC on May 21, 2014
That is a jolly good question!
I have always just used the bucket of salty water method but I have a couple of 2200's that I really need to "kill" so I will probably give the KonaRC method a go. The thought of scoring cells scares me a little too! I will be interesting to hear some feedback from people who have tried this.
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Trauma50 on May 22, 2014
I found a great way to get rid of dead LiPo's. Put them in a bag, Take them to Lowes/Home Depot. Right inside the door they have recycle bins for spent batteries used in cordless tools. They can be made harmless buy someone/company that knows what they are doing.
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Red20RC on May 22, 2014
Ha! That's awesome 😂
Probably THE best advice I have heard so far.
I must go and check if our Australian equivalent (Bunnings Warehouse) offers a similar service.
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victour20010 on May 22, 2014
Take spent lipo's to Home Depot and forgo learning through experimentation, awe c'mon where is the fun in that. ;) Just kidding with ya. Trauma50, thanks for the good suggestion. Fyi, in the past I have given Alkaline batteries to BatteriesPlus; I think they might accept Lithium Polymers as well if anyone is interested.
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jetpackninja on May 22, 2014
Excellent discussion. A couple of fairly recent events have led me to move all of my charging activities out of doors. I've also moved my field charging out of the engine compartment of the truck. Look at the amount of smoke produced in this event, trust me, you don't want that smoke in your house or even your garage ;)
Do your self a favor and don't charge indoors.
This vid and discussion may also have me rethinking my storage strategy. I'm thinking my stuff will be out in the garage (in cinderblocks) instead of in my workroom and workbench. Thanks for posting.
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victour20010 on May 22, 2014
jetpackninja I hope the "fairly recent events" were not too bad. I would be interested to hear about them..if...you want to share. Lipo's exploding is scary, it definitely has made me uneasy and has caused me to change some habits as well. I recently purchased "LipoSack" for each of my lipo's and I am currently making a safer charging station that will include using the liposacks and a .50 caliber ammo can. I plan to make some vent holes on top of ammo can.
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jetpackninja on May 22, 2014
Recent event #1 (was pretty bad)
A good friend (knows better) left 6 batteries to charge in the basement. There was no house fire but the smoke from the batteries was picked up by the A/C unit and distributed though the house. Insurance covered the hazmat cleanup, but he and his family had to vacate for three days.

Recent event #2 (not bad)
Charging at the field using the car battery and charging at 1c. Noticed the battery a little puffy and was very hot to the touch. The charger was happily chugging away and no doubt would have kept going until there was a failure. Pulled it off the charger immediately and let it cool.

I've always charged in a bunker, but now have move my blocks and charging setup outside.
Field charging is done on the tailgate with a marine battery.

Ammo cans and lipo bags (as well as any kind of bunker) are better than nothing but will not do anything to contain all of that nasty smoke.

The only fires I've had were batteries that were damaged in combat (prop slashes) and while discharging a damaged battery (outside of course).

This article has reminded me that a battery that looks OK may still be "bad"
I think it has helped me understand that I have been complacent about my battery handling.
I'm going to rethink just throwing all of my uses batteries into the flight box and not giving them a second thought. Definitely won't be just tossing a flight box full of batteries into the plane room, And no more leaving old weakened batteries on the bench for tests...
I'm thinking a cinder block storage bunker in the garage...
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itssean95 on May 24, 2014
This article made me realize just how dangerous these lipos can actually be. I never realized they could go off the way that one did i just thought they could catch fire if impacted or discharged too fast. Is there a safe way to charge low voltage batteries though? I have 1 or 2 that had been sitting simply too long after a flight, a few months, they weren't in a crash or anything just neglected. Can i save them still?
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Red20RC on May 28, 2014
I've been holding off on commenting on this question as I don't want to give wrong/bad/dangerous advice.
Way back when lipos first came out I had some 3 cell 800mah 5C batteries that I would regularly cook and over-discharge. At the time is was recommended to put them on a NiMh trickle charge until they reached 3.3v per cell, then swap them to a lipo charge to see if they recovered.
I did it quite a few times and it seemed to work. The batteries were like pillows and didn't last long but I/we didn't know any better at the time.

Basically - JUST DON'T DO IT! I know some people have a bigger modelling budget than others but you can get a 2200mah lipo from HobbyKing for around $7 these days (and they are flippin' good batteries as well). Just ask yourself if your house/family/health is worth $7 for a new pack?
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victour20010 on May 25, 2014
I am no expert, but I would say that if the voltage per cell is at or below 3 volts or if the battery pack is puffed then, at this point the battery should probably be put out of commission.

In general, after a flight, you want to keep voltage at or above 3.72 per cell.

Some time ago, I found an interesting write up on lipo batteries. You may find it interesting as well. It is located at http://www.rchelicopterfun.com/rc-lipo-batteries.html.
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Shufty on May 28, 2014
For Aussies, places like Battery World will take your old/dead/puffed lipo's for free. I've disposed several there, no worries. Much easier than buggerising around trying to render them inert yourself.
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Red20RC on May 28, 2014
That is definitely worth knowing. I've got a battery world down the road - might pay them a visit tomorrow.
Thanks for letting us know :)
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LiPo Safety