Burn out when connecting battery to ESC - RC Groups
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Jan 02, 2013, 04:17 PM
derp express's Avatar

Burn out when connecting battery to ESC

Hey all,

I recently got a 6000 mah 3S battery to use for one of my FPV planes. This morning, I tried to hook it up to my ESC and I immediately saw the inside of the 4mm bullet connectors start to spark like hell. I immediately disconnected the connectors, but before I could do that, a section of both wires between the ESC and the battery at the neck of the connection melted and came apart. If I hadn't been wearing gloves, I think I might have seriously been hurting right now. The ESC got a little warm also. Anyway, about 2" of wire beginning from the connector going to the ESC now looks like it's baked, and when I stripped off the insulation, it had this sort of brittle powder it was coated in. I cut further down, and that stuff seems to have faded off on the bits of wire closer to the ESC. Now, this ESC is fairly new, but I've used it before, only with different batteries (both 2s and 3s) So, it left me wondering a couple things:

- What is the most likely cause of this, and how can it be prevented?

- The ESC shows no obvious signs of damage - can it be used again?

- The battery also shows no obvious signs of damage aside from a tiny dark spot on one of the connector bullets, and there was no change in temperature when this happened, so I don't think it was over discharged - is it safe to use again?

My initial thought was that this was the result of terminals that were exposed to each other at some point causing a short, but I couldn't find any sign of this. New batteries / ESCs can always be bought, but my main concern here is how to I avoid a situation like this again? I'd like to keep all 10 of my fingers in the future.
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Jan 02, 2013, 04:56 PM
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Mark Wood's Avatar
Reversed polarity? If you have the same type of connector on the battery or esc that can happen. Male on one side, female on the other will prevent this.

Jan 02, 2013, 04:59 PM
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Dr Kiwi's Avatar
Check the polarity of the pack itself.. it may have had the incorrect colored leads fitted when it was made in the factory (I've had one new pack like that!).
Jan 02, 2013, 05:00 PM
Registered User
First simple minded thought is the battery plug has the polarity of the wires reversed At the plug or inside the battery.................Try to charge the battery..........Charger will tell you if the polarity is O K or not.
Jan 02, 2013, 08:30 PM
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Mark Wood's Avatar
Check it with a meter before doing this. ^^

Jan 02, 2013, 09:22 PM
Wake up, feel pulse, be happy!
Piece's Avatar
Yup, sounds like reversed polarity on the battery or ESC connector. Check both of them, and check the actual colors of the wires against the standard for the plugs you're using.

As for the damage toll, the ESC is probably toast. You can try powering it up again if you want, but if it does work and you do start flying with it, there'll always be that nagging feeling (justified or not) that it took unseen damage and might fail at any moment. The battery, on the other hand, is most likely fine. You'd have to suck a LOT of current from a half-decent 6000mAh pack to really hurt it. I suspect melted solder joints and burnt insulation are only the beginning of the suffering it can dole out before being injured itself.
Jan 02, 2013, 09:50 PM
Registered User

There is NO POSSIBLE way to EVER take your eyes off of the battery when you are using it or recharging it................Just too big of a future risk.

PLEASE charge this battery outside on concrete with a BIG metal can or cover over it.
LIPOS do just throw a fit with no puffing. 3 cells of 6000 mahr will throw flaming battery bits around if it goes.

If you can afford it. Replace it. .......I would seriously contact the seller for a ESC & battery replacement.

Good luck with a replacement

Jan 03, 2013, 05:44 AM
Life begins at transition
I've had the same happen to me (assuming it's not reverse polarity - on mine it was the 30th or so time I'd used the same ESC/batt)

Grab a multimeter and measure the resistance across the two battery plugs. It should read in the millions of ohms, and decrease as the capacitors charge.
Mine showed a dead short. Not good!

Don't know how it developed, but that ESC is now in the scrap bin. Haven't searched for where the short came from - don't care either.

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