Exploding LiPo and aircraft fire - scared my son.

[Russ2706]

I converted my old 45 powered Arising Star to electric propulsion a while back so my son could fly in on local farm land, and after learning how to optimise the system it was flying really well until today. The battery had been fully charged using the recommended 'intelligent charger' (iMAX B6AC) but the motor seemed down on revs and he didn't fly very long. Back at the house we reconnected the charger and an hour later the battery (14.8v 3,500mAh LiPo) exploded with a serious of loud pops. I thought that was it, but I put it outside in the back yard as the battery pack felt too hot to remove - 10 minutes later I saw a cloud a black smoke and the fuselage was actually on fire. I had an extinguisher handy but what if I hadn't been around ? It could have burnt my house down. We're all pretty shocked......

 

[luke66]

Yep. Lipos are no joke.

 

[Doom!]

Glad you were there to take care of it quickly. I'm starting to think oven mitts should be in everyone's tool kit.

 

[DavidB1126]

No thanks I choose LiFE

In all seriousness I'm glad everyone is ok.

 

[CertifiedMike]

Glad you are all ok! Sorry about your battery and your plane!

 

[9x19]

I'm glad things turned out mostly ok.

Incidents like this is why most of us here recommend to never charge a battery unattended.

 

[Russ2706]

Is this a common occurrence? I never had any problems with nitro or diesel engines and only a year or so of electric, so I am worried. My lad also has a bunch of the Hobby RC 4-channel foam planes with 1S batteries, so am I going to have to store them in a steel container outside? `

 

[9x19]

Common? Not at all.

Given the tens of thousands of lipo batteries in consumer hands, the number of reports you see are a tiny percent, but the possibility exists, and as you've seen, the numbers don't mean much when it happens to you.

 

[Doom!]

Read up on the do's and don'ts for lipo safety and you will be fine. Always better to err on the side of caution.

 

[Russ2706]

I bought the correct 'intelligent charger' and thought I had understood it all but you're right - these very high power density power packs are not just dumb 'batteries' but things that need careful management. See attached photo I took this morning after the thing had cooled down overnight.........

 

[Russ2706]

New battery on order for replacement model has interesting advice - check items (5) and (7) on their sales advice attached.......

 

[WickedFog]

Glad you were there to take care of it quickly. I'm starting to think oven mitts should be in everyone's tool kit.

Oven mitts would be like throwing gasoline on a fire. Welders gloves would offer a little more help than nothing at all

New battery on order for replacement model has interesting advice - check items (5) and (7) on their sales advice attached.......View attachment 244755

Do you know what settings you used on the charge cycle you were running?

There are a number of reasons a LiPo can seemingly spontaneously burn up and vent a ton of heat and toxic gasses into your home.

If you mistakenly started charging it in the wrong mode, or set the wrong amperage, that could push the LiPo into the danger zone. Trying to chsrge or discharge a damaged LiPo can also cause

And just so you know, that is not a smart charger. No worries, as the smart battery/charger tech is gsrbage anyway. So the first thing you should do is get a good charger. For a charger in the price range around $120 or less, the best option is the Hota D6 Pro.

A guy on YouTube by the name of Joshua Bardwell has some videos on LiPo charging, LiPo safety, etc. Its definitely worth taking sla look around his channel

If you do put a couple hours into studying up on this stuff (and I highly suggest you put in more thslan that), just pop back here and ask for help if there is anything you are struggling to understand. I have been an RC nut for 42 years now and all you gotta do to prevent a LiPo fire is learn and implement safe practices by keeping a close eye on the health of the batteries you use. Also, make sure BEFORE you hit start on any charge cycle that you are using the correct settings, Keep an eye on the cables, battery wraps, hard cases, etc. If you see any swelling of battery at all, get rid of it ASAP, after completely draining it of course.

 

[Russ2706]

That's really interesting commentary. I have already found a replacement Arising Star on Ebay, and have new servo's, and now a 4,500mAh 4S pack on order to get my son flying again, but I now doubt what I was sold as the "intelligent balanced charger" (iMAX B6AC) is not right? It wasn't cheap here in the UK. It always selected 1.0 Amp charge rate, which seemed reasonable to me. Any advice on a safer charger? From now on, all re-charges will be done outside!

 

[Russ2706]

Sorry - saw you recommend the Hota D6 Pro charger. I will check out UK availability. Other folk have told me my "intelligent charger" is actually pretty dumb, and does the same re-charge programme regardless of battery state. So if my son flies for only 10 minutes, the iMAX behaves as if the LiPo is completely drained. So.....probably, we have been over-charging this last month at least.

This is great learning by the way, very effective because I can't really get any local advice.

 

[Russ2706]

This is very instructive (thanks!)....

 

[WickedFog]

That's really interesting commentary. I have already found a replacement Arising Star on Ebay, and have new servo's, and now a 4,500mAh 4S pack on order to get my son flying again, but I now doubt what I was sold as the "intelligent balanced charger" (iMAX B6AC) is not right? It wasn't cheap here in the UK. It always selected 1.0 Amp charge rate, which seemed reasonable to me. Any advice on a safer charger? From now on, all re-charges will be done outside!

As I mentioned, the Hota D6 Pro is the best entry level charger. It even has plenty of headroom if you get into some larger batteries.

To figure the charge rate to use, you first need to find the 1C rate for your battery by converting your battery's mAh ratingn to Ah. You do that by simply dividing the mAh rating of your battery by 1000.

So a 5000mAh battery 1C charge rate would be:
5000 ÷ 1000 = 5

So in the charge cycle, you would set your charge rate to 5A.

To find the 2C charge rate, simply multiply that Ah value by 2:
5000 ÷ 1000 = 5
5 × 2 = 10

So to charge a 5000mAh battery at a 2C charge rate, you would set the charge rate to 10A

To make sure you get it:
For charging a 450mAh LiPo at a 1C rate:
450 ÷ 1000 = .45A

Convert that to 2C:
450 ÷ 1000 = .45A
.45 × 2 = .9A

As long as you are charging a healthy LiPo battery, you can safely charge at a 1C or 2C charge rate. Even higher for most batteries. But the higher you go, the higher the chance becomes for a failure.

 

[Russ2706]

Right, so a 3,500mAh 4S pack at 1C rating would be 3.5Amps, yet my charger was supplying only1.0A, which should be very safe, or am I missing something? The battery no longer exists so I can't see any specs or the 'C' rating which you're steering me towards.

 

[WickedFog]

Right, so a 3,500mAh 4S pack at 1C rating would be 3.5Amps, yet my charger was supplying only1.0A, which should be very safe, or am I missing something? The battery no longer exists so I can't see any specs or the 'C' rating which you're steering me towards.

Just to clarify
LiPo batteries have a C rating. It represents the maximum rate a LiPo battery can safely release the go juice it's holding inside.

The C rating on a charger is how fast you are putting the juice back in.

As for the charger showing only a 1A charge rate - What was the original value you set in the charge cycle?

 

[Russ2706]

The charger detected 4S/14.8V and suggested 1.0A and I just clicked yes. I assumed that was all I need to do, but am wising up now to there is a lot more to LiPo management than I'm used to ref NiCad

 

[Mrgoodwrench35]

Sorry to hear about your damaged plane but it sounds like it was a very educational experience at least.

Ill second the recommendation on the HotaD6. Its my favorite charger and I've went through several over the years.

I'm also of the opinion that the 'smart' battery/charger stuff is a gimmick. Its better to be educated yourself than rely on cheaply made tech to do the thinking for you.

As WF mentioned, I keep a heavy pair of welding gloves on top of my charge station. I do charge indoors in my garage but never unattended and never have them stored in the vehicle while not in use or charging. May as well mitigate your possible losses.