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Old May 16, 2006, 11:41 AM
Zlin Flier
Rick McWilliams's Avatar
Ventura CA
Joined Dec 2003
459 Posts
check battery wires for possible short

The rapid onset of fire seems unusual. If the battery wires shorted that would cause a hot fire right now. It may be that the connection to the battery has poor strain relief and the wires caused the battery terminals to short.

I fly a TRex XL with 430L motor, and align 35esc, 665g weight. My hover current is only 6.5 amps. The low C rating is not likely the problem.
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Old May 16, 2006, 12:07 PM
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i dont think brake would do much in a trex. they have a 1 way bearing. even if the maingear froze from the motor brake, the rotor head would continue spinning.

have you ever seen the graphs of motors during spoolup? look at that 30amp spike@13seconds during spool up (right before the nice easy hover amp).


if he spooled it fast, maybe that spiked it way past the burst capacity. the above graph is probably a perfectly setup heli. with problems in the heli it could be a lot worst.

i personally dont trust the align esc's although i have seen both good and bad examples.

as for motor problems. i seen long motor screws causing people to blow up their powertrain. i cracked open a couple burnt motors that i got ahold of...makers are compressing more copper and stuff into these things, it's so tight there's no room for error. a stupid metal shaving from the mounting screw falling into the core of the motor might short the damn thing. or maybe the mounting screw just makes direct contact inside on the windings because it is so long.
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Old May 16, 2006, 04:07 PM
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ok everybody listne lmfao. This is what i have. No binding!!!! I make sure i run a peice of paper through my gears to get proper clearance. I am using and 11 tooth pinon. To big? To small? Any help. And i dont know why I put i had braking in there. I just realized I wasnt using brake at all. I have to much rc stuff it gets to confusing lol. More help on this would be greatly appriciated! the going capasity is 22A and burts is 30 amps. Also I forgot to add that the night before when i was soldering some stuff to the battrery i shorted the wires for a few seconds by accident (very scary!). Then i charged it without a balancer. Don't know if this would have anything to do with it either? Thanks

Todd
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Old May 16, 2006, 04:17 PM
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shorting might have been the cause... u should constantly check the cell voltage alances in any damage. just balancing them doesnt work. If a cell is damage, the voltage of it will drop faster that other cells over time, means !good. The fact that u might needd to balance it would mean it was damaged from the start
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Old May 16, 2006, 05:27 PM
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Quote:
Originally Posted by Live2die420
Also I forgot to add that the night before when i was soldering some stuff to the battrery i shorted the wires for a few seconds by accident (very scary!). Then i charged it without a balancer.

Todd
That would probably be what happened. They have the warnings written all over the place about not doing things like this, and how damaging it can be to the cells. Let this be a lesson, and be happy nothing more than the pack was damaged (house, car, person).
Don't take chances with Lipos, although it may be tempting to save a couple dollars on the cheaper, lower capacity ones, what have you, if it causes stuff like this and burns down the house, where is your couple of dollars? Not to beat a dead horse, but if you aren't good at soldering such that you short stuff, it might be worth it to buy packs with pre-soldered connectors.
Good Luck!
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Old May 16, 2006, 05:58 PM
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above is the EXACT cause. do you know what shorting is? it's high current because there is only the resistance in the wire from positive to negative which is probably VERY VERY low.

V=I*R if V=11.1v and R of shorted wires is probably 0.0000001ohm then I(current) must be a HUGE number for sure more than 30amps burst capacity.

lipos have ZERO tolerance for this kind of abuse. shorting for a microsecond is good enough to damage it permanantly or so i have read in the battery tech forum. 1 spark and it's over. you got to be really careful with them lipos especially when soldering, desoldering, adding connectors whatever.

doing that you probably wouldve killed any lipo regardless of the C rating unless it had some protection circuit built in, which i havent really seen in mainstream lipos.

stop blaming the equipment for failure!!
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Old May 16, 2006, 06:40 PM
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yes i know what shorting is everyone i have taken a lot of electronics classes lol. I just though i had the connectors seperated, let go of them, bent down to unplug the soldering iron and zap! sparks everywhere! lol. Kinda funny now but not at the time ill tell you that! Thanks for your help. So now that i have the same pack but brand new can i run this? If not I just bought an rc18t do you know if it will fit in that car?
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Old May 16, 2006, 08:16 PM
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I'll say it again, you are definitely better off with a higher discharge rate cell. If budget is a big concern, look at the Apex Mk3 15C packs, great value per dollar. TP2100s are great if you want to pay for them.
You may have "taken electronics classes so you know what shorting is" but clearly you did not understand what it did to your cells. Please don't kid yourself, these things are DANGEROUS. The next time you might not be so lucky. When soldering connectors, solder one wire at a time, keep the other one covered, heat shrink the first, and THEN do the second wire. Taking shortcuts here is what is going to cause you trouble and cost you money. If you aren't willing to take the time to do stuff right, you won't have much sucess.
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