Explosion! Fire!

[vertman]

If you were to crunch numbers, based on the run time, wouldn't the batts have been well drained after 4-5 mins? To be fair none of us would run the zippy batts, especially only 4000's for such a long run time. If the lvc was set set at 3.0v the esc would have cut out well before the batts had drained too low. The most likely cause of the op's batt failure was that they were too run down too often. Vertman if you want long runtime you need to go 2p but you still have to know how much you taking out of your batts if you want them to survive. 80% max is recommended, which you can determine by how many mah go back in when charging. Sadly dude these exploded batteries are due to too much over discharging, they just couldn't take it anymore.
Unfortunately there has been a lot of bs in this thread that has not really been too helpful for the op either. C'mon guys it's not just about personal bents and opinions, but the guy just was trying to figure out where he screwed up so he could learn.

Thanks Peter - you are correct - I'm just on here to learn and as you mentioned there have been varying opinions on this thread and I'm still a little lost. Some are saying if they were discharged there shouldn't have been a blast etc. Some are saying too much heat, now others are saying i was slow. LOL. I would generally put about 3700 Mah back into the pack when charging. I am a total noob at this and learning as I go. Unfortunately this learning experience cost a few bucks in new lipos, new esc and a fiberglass repair kit. fortunately I still have the stock Revolt motor and ESC that I will probably throw back in once i am done repairing the hull. I will grab some high C 2S packs and learn some more before upgrading to a faster boat.

[T.S.Davis]

30c cells (low for boats these days)
only 4000mah (no where near enough for the time)
running 4 minutes plus (see above)
4mm motor wires ("resistance is futile".....a wise man once said that in a magazine)
traxxas on the battery side (more resistance to build heat)

Put that all together and magic smoke is coming out somewhere.

I don't own a boat that I run more than 4:20 and that's usually at or around 7000mah on board. So the OP probably over discharged repeatedly. Then the cells flipped him the bird.

Any cells will suffer if drained too far multiple times. Then after injury ask them to deliver amperage.......again........again.........again. They're going to fail. I think we've all injured packs. I have some now that I know for certain are going to fail. Just don't know when. I wrecked em.

The Poly RC cells were awesome too. Anybody remember Tanic? Those were the "gotta have em" cells for a while. Think they were 12c. Flight Power went 25c and we all lost our minds. Bought a bushel of those. Still have some. They're absolutely pathetic.

[T.S.Davis]

. I would generally put about 3700 Mah back into the pack when charging.

Don't stress. These guys are mostly picking at each other. Everybody knows everybody on here to a degree. They're all good people. For real.

You don't know. There isn't a text book to learn it either. You want to avoid drawing your cells down past 20% remaining. So you 4000mah packs should never be taking more than 3200mah after a run. This is especially true of less expensive cells. They're less forgiving.

[Make-a-Wake]

Why do you say "only 120 continuous amps available"? The C rating only tells you how many amps they can sustain without damage to the cells, it doesn't limit the amount of amperage that they will put out, they certainly will put out more under heavy loads, they just may not survive it.

Because when they are 4000 mah and 30c that equates to 120 CONTINUOUS amps, burst is higher. That's basic lipo knowledge

[Brewbud]

Don't stress. These guys are mostly picking at each other. Everybody knows everybody on here to a degree. They're all good people. For real.

You don't know. There isn't a text book to learn it either. You want to avoid drawing your cells down past 20% remaining. So you 4000mah packs should never be taking more than 3200mah after a run. This is especially true of less expensive cells. They're less forgiving.

Great reply

[Peter A]

Ok so run the revolt on 4s with stock motor and esc. Turnigy blue 5000mah 40c packs are pretty cheap and ok for sport running or racing which I've done, although the quality can vary. But it won't hurt to spend a little more on some revolectrix 2s 5500mah 70c hv packs, they are a better battery. They will be good for your next boat too. Yes I am recommending them and am sure you will get great service as well.
There is heaps to learn, so troll through the different threads and continue to ask questions.

[montymike]

Don't give up on trying new combos, thats what makes this
Hobby fun....

[kevinpratt823]

Because when they are 4000 mah and 30c that equates to 120 CONTINUOUS amps, burst is higher. That's basic lipo knowledge

My point was that with the use of the words "only" and "available" it could be misinterpreted, as in the current output is somehow regulated/limited, and you used that as a basis to rule out the batts as the issue, that is all. Maybe I'm the only one who read it that way, but some people new to this may not have all the basic lipo knowledge yet so I didn't want anybody else to take it wrong. I think many packs will in fact sustain the burst rating continuously if demanded, but damage is likely.

[keithbradley]

They were Zippy 30c 4000mah from HK running 6S on a 120a Turnigy ESC on a M445 prop. Little too much? Lol. She ran 52 mph on glass. That was before the explosion. I will post pics when I get to sit down at the computer. I was using 4mm Bullitt connections for the motor to esc and traxxas connectors on battery. They were all intact even after the fire.

Did you balance charge your packs?
I don't think 4mm bullets or traxxas connectors caused your problem. Likely just a parts failure.
How old were the packs? Were they puffy at all before you ran?

[montymike]

[Brushless55]

They were Zippy 30c 4000mah from HK running 6S on a 120a Turnigy ESC on a M445 prop. Little too much? Lol. She ran 52 mph on glass. That was before the explosion. I will post pics when I get to sit down at the computer. I was using 4mm Bullitt connections for the motor to esc and traxxas connectors on battery. They were all intact even after the fire.

Boat suddenly stopped in the middle of the pond. Sat still for about 20 seconds and then BOOM! Blew the lid of my Revolt 30 about 10 feet into the air and then she burned..... was able to send my rescue boat out and tip it over to minimize fire damage.

Turns out the Lipos both exploded.

I had run my setup numerous times with some heat but nothing crazy. The esc was fire damaged but otherwise appeared fine.

Why would the lipos explode? How do I prevent that from happening again?

I have pics and will upload when I figure out how to do it.

It was/is a revolt 30 with a 1500kv proboat motor. I wasn't timing the run but the run was almost done. I would get about 4-5 minutes on those batteries.

So my question is when I rebuild I would like to keep that setup. Do I go with a 180a esc 6 mm bullets and higher c lipos to avoid this happening again?

Surprisingly none of the connectors appeared to have any damage. I'm wondering if maybe one of the wires was touching the packs and got so hot it melted through

From what I am reading your spinning a 45mm prop at a decent rpm with 4000mah packs for 4 to 5 min
that is your problem in my opinion
to much pull for a very long time on those 4000mah packs

[jim82]

How much mah was in the packs after the runs? That is a long run time for even 5000mah in series with that setup. Good looking out brushless

[jim82]

1500kv is is low amp pull should be but if you are running it really wet then it eats energy up.

[Brushless55]

How much mah was in the packs after the runs? That is a long run time for even 5000mah in series with that setup. Good looking out brushless

thanks, and that is a long run in my opinion

1500kv is is low amp pull should be but if you are running it really wet then it eats energy up.

1500kv on 6s could pull some decent amp numbers

[gsbuickman]

I tend to agree with brushless 55 & Carl.

Your 4000mah packs average 120A continuous output which is pushing it on a T120 ESC, but 4-5 minutes is too much. On 5000mah packs most prefer to limit runs to 4 minutes, myself included because I don't believe in running packs into the lvc.

I think the packs over discharged due to a faulty or disabled lvc, and a cap probably blew, caused a short & blew the cells. I had something similar happen when an AQ ESC went south awhile back playing with a ul-1. I would recommend a T-180 or better ESC, 500mah + cells and 5.5mm connectors instead of the stock trx connectors. Personally I've had better luck with deans, but I don't trust trx for more than 75A continuous...

http://www.ebay.com/itm/310894441835...%3AMEBIDX%3AIT
I

[vertman]

Did you balance charge your packs?
I don't think 4mm bullets or traxxas connectors caused your problem. Likely just a parts failure.
How old were the packs? Were they puffy at all before you ran?

packs had maybe 20-30 runs in them - always balance charged and not puffy

[vertman]

I guess I was under the false impression that the LVC would kick in and protect the packs from draining too low.

so far the opinions appear to be

1) cheap packs
2) capacitor in ESC blew
3) bad connectors (4mm bullets and traxxas) too much heat and impedance
4) too long run time
5) packs shouldn't explode if they were discharged
6) 4000 mah too small

[Doby]

LVC is a bit of a joke and should not be used as the be all and end all to keeping LiPos safe.

Remaining capacity is whats important. Timing runs is the main way to keep the batteries happy

Where in Ontario are you?

[Make-a-Wake]

I guess I was under the false impression that the LVC would kick in and protect the packs from draining too low.

so far the opinions appear to be

1) cheap packs - POSSIBLY
2) capacitor in ESC blew - DONT THINK SO
3) bad connectors (4mm bullets and traxxas) too much heat and impedance - YES
4) too long run time YES
5) packs shouldn't explode if they were discharged - ??
6) 4000 mah too small - YES, IN MAH AND IN C RATING(30C)

[Fella1340]

I can understand all the prop, voltage and low mah batteries being contributing factors to the explosion but for two batteries to go at the same time there must have been some kind of epic dead short. I would be curious to see the inside of the esc and where the damage occured. The packs aren't that poor of quality. Lots of people run them without issue and the op says they were still balancing nicely and never puffed. The motor didn't have any real bad burned out spots, i wonder if it's still a runner or not. If it is, the esc may have simply dead shorter across one or all the phases. That would make some crazy stuff happen. Just my guess, it would be good to hear back on the motor.

[Peter A]

Is it possible that being over discharged the batteries created an explosive gas that was ignited by a short? It would explain the result.

[kevinpratt823]

I don't think it's that strange to see both packs go together when in series. If it was a single 6s we probably wouldn't be thinking nearly as much of it, and essentially that is what it is, just separated by a bit of space. It may not have been so much an "explosion", as just so much pressure built up in the puffing cells that when the foil finally let go it was enough to blow the hatch off, then the exposure to the elements just continued the process of destruction......just another theory though.

[Brushless55]

interesting

[Brushless55]

I guess I was under the false impression that the LVC would kick in and protect the packs from draining too low.

so far the opinions appear to be

1) cheap packs
2) capacitor in ESC blew
3) bad connectors (4mm bullets and traxxas) too much heat and impedance
4) too long run time
5) packs shouldn't explode if they were discharged
6) 4000 mah too small

When we race in NAMBA20 our races last less than 2min and we run 5000mah and bigger packs, some races last just over 1min
and we come back with 20-35% left in our packs
for what its worth....

[kevinpratt823]

FWIW, people run lipos down to 3.2v in cars all the time with few problems. I have set my cutoffs up to 3.3-3.4v in my cars over the past few years after I learned my lesson with boats, but it obviously has more to do with the kind of constant draw we pull from them when they get lower. The same 5000 mah that gives me probably 15 minutes runtime in my 1/10 2wd buggy has no problem running right down to lvc of 3.2 v because the draw is nowhere near as high or continuous at the end of the charge, same pack in a boat, pulling a steady 100+ amps, will likely puff if I continue to run it down past 3.6v