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Topic: 10 gauge wires warm at (80?) amps R/C esc (Read 319 times) previous topic - next topic

DocStein99

I built R/C lawnmower, runs off (2) 12-volt lead 18 ah batteries, Sabertooth 2x32, a FLYSKY R/C controller and Arduino central computer.  The robot works great now I want to improve, and make it safe.
 
To the 80-amp R/C ESC that runs the main mower blade is a brushless 3 wire motor at 24 volts.  I think there may be around 16" wire between the battery pack 10 gauge.  After mowing for about 40 minutes I notice the wires are WARM.  I forgot to take specific temperature.  With my hands, I compared to the wires from/to Sabertooth driving the wheel motors, those wires are normal temp to the frame of the entire robot.

So obviously I have to do something about the wires to the ESC. If I replace the 10-gauge wires to 8 gauge, will I be losing power?  Are fatter wires just better altogether to use - is there any disadvantage, should I even replace them with 6 gauge wire?


Wawa

#1
May 18, 2017, 02:54 am Last Edit: May 18, 2017, 02:56 am by Wawa
Warm wires is not a problem, but you loose a (tiny) bit of power.
Thicker wires (or a second wire in parallel) reduce (halve) the problem.
Leo..

MarkT

If wires get hot thicker wire (or silicone insulated wire) should be considered - silicone
insulation can stand very hot wires without damage, often used to save weight in RC aircraft etc.

Heat loss in a wire is proportional to current squared so a good solution is go to a higher voltage
thus reducing the current - even a 30% increase in voltage will make a big difference to
heat dissipation in your wiring for the same load power.  As a wire heats up its resistance
increases a bit, so cool wires are generally a good thing.

Just make sure your fuse fails before the point wiring gets damaged... 
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

jackrae

In answer to your question, the greater the wire's cross-section (ie fatter the copper) the less voltage loss it will experience and hence the less heat it will generate.  So the thicker the wire the LESS power you will be wasting.
Heat generated (in watts) - the wasted power - is directly proportional to wire resistance so the lower the wire's resistance the less wasted heat is generated and the more efficient you system becomes.  10 gauge isn't ideal for a sustained 80 amps load and 8 gauge will certainly improve matters but 6 gauge will be better, if you have space for it.

DocStein99

Ok so if bigger wires make it better with no consequence to the electric supply of power - I will try and use 6 gauge wires.

The PROBLEM with that is, the 14-gauge wires OUT from the ESC are SOLDERED to the very small circuit board, as it's designed to be installed in a R/C airplane to save space and weight.  I can solder / crimp 6-gauge wires to the 14-gauge short leads extended from that circuit board confidently.  I do not feel confident soldering 6-gauge wires directly to the circuit board, since I actually have to use a small torch to heat a wire that thick in order to solder it.  I guess I would have to get creative and solder some bar-stock or solid copper to the board (if I could do that without ruining it) and then solder or crimp the 6-gauge wires to the solid copper stock.


jackrae

I'd suggest you use EC5 connectors to couple the 6 gauge cables to the ESC output leads, and try and increase the 14 gauge output leads either by doubling them up or using whatever gauge you are comfortable with. you need 4 wires of 14 gauge in parallel to be equivalent to 6 gauge but providing a single length of 14 gauge is short enough, the power loss through it will be minimal.

By "torch" do you mean an electric soldering iron or a naked flame.  I'd try and avoid soldering direct to the PCB unless you are skilled at soldering heavy leads and you have a 'meaty' soldering iron (100 or 200 watts)

Wawa

Forget about everything.
Slightly warm wires after 40minutes is NOT a problem.
Leo..

jackrae

Forget about everything.
Slightly warm wires after 40minutes is NOT a problem.
Leo..
Probably the best solution all round.  Too often we try and solve problems that don't really warrant the effort.  Unless "warm" actually means 'hot' then as Wawa says "... Not a problem."

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