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[captain_reg]

Had a bit of a 'learning opportunity' this morning.


Doing some troubleshooting of a suspected loose connection in the wiring between the speed controllers & the receiver I suddenly had billowing smoke from my series connected 6v 3700mAh NiMh batteries. Managed to grab hold of the deans connector and disconnect. Worried I'd fried everything but it seems that the only thing damaged (except the batteries) was one of the Mtroniks tio 30 speed controllers which no longer runs in reverse.


Still no idea what I did wrong or if the speed controller just happened to fail short circuit as I was working on it (doubtful I know). I'd have expected that if I'd shorted something related to the BEC (which I was tinkering with) that I'd have melted the small gauge wires connected to that.


Anyhow.. onto the learning. The batteries according to the component shop website will deliver 30 amps and the 14awg wires are rated for 35 amps. I was using an auto resetting 'marine' fuse (30 amps). So it seems the batteries will happily deliver 30 amps short circuit but not enough to blow the 30 amp fuse. The connections between the cells will not withstand that and end up glowing cherry red.


I assumed the batteries were toast and the fuse was faulty so I intentionally shorted them through a 'normal' micro fuse which revealed that a 20amp fuse would blow within a second or two. 25amp fuse would also blow eventually but resulted in a faint whiff of smoke from the (tortured) batteries and melted the fuse housing. 30amp fuse would happily sit there without blowing causing the cell connections to glow red. Nothing else in the wiring showed any signs of distress (14awg wires, deans, wago & 4mm bullet connectors)


Swapped all my fuses out for max 20amp.

[Akira]

Cap, If I remember correctly, fuse rating, especially the auto reset type, have a +- range. It sounds like you chose to use all the same ratings, battery , wire gauge and fuse limit, as your guide. Personally, I chose my ESC with at least +10% of the stall current draw of my motor. When I fuse my motor circuit I chose a rating that is maybe +25% of the motor's max load draw, but not the stall current.The fuse is designed to protect your wiring, so you should have good there.
You definitely moved in the right direction by dropping your fuse rating, but you may be able to drop it even more, to say 20 amps.That should protect your wiring, and hopefully your ESC as well.Good luck... and welcome to the Magic Smoke Club