Battery to Controller wire size?

Earth_Bike

1 µW
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Going to be running a short run of wire, maybe 14" (~350mm) at most, from the battery to my new controller, wondering what wire size to use??


What is everyone else using to run from battery to controller? 12awg? Is there such things as overkill when it comes to this?
TIA
 

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For that length, and the controller size, 14g is fine. But in general, its still good to go with some high strand count silicone insulated 12g wire from the RC toy and drone suppliers. Change the connectors to better ones on the controller, using a good RC connector matched to fit the 12g wire. Better connectors can handle the spark created by connecting the controller to the battery. they will spark at the tip, but the larger contacts then slide in and make clean contact.

You can overkill, but as long as the connectors match, its no problem. Cramming a 10g wire into a contact made for smaller wire is problematic. The oversize wire can cause some contacts to not work properly, with the insulation causing contacts to back out of housings and lose contact, or other problems.
 
Earth_Bike said:
Going to be running a short run of wire, maybe 14" (~350mm) at most, from the battery to my new controller, wondering what wire size to use??

What I dont understand is.. if this controller is rated for 25amps max, how can they use what looks like 16-14awg coming out of the controller from the factory? Is it due to the short length?

Less than 0.4% loss given the inputs is very reasonable.

You are going to lose roughly 1 watt at 12 amp (576w motor output). Even less than that given you won't run that much power on average.
 
Earth_Bike said:
Going to be running a short run of wire, maybe 14" (~350mm) at most, from the battery to my new controller, wondering what wire size to use??

http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/wirega.html

2.525 ohms per 1000 ft.

So for 18 inches or 1.5 ft:

2.525 x 1.5/1000 = 0.00379 ohms

Power losses at 25A peak:

(25 x 25) x .00379 = 2.37 watts
or
2.37 / (48 x 25) = 0.2%

Based on this estimate (no coffee yet, so double check the math), I'd say you could get a better performance bump eating a can of beans and farting while riding. So, from an environmental emissions standpoint, go with 8 gauge.
 
I'm no engineer, but basically the only reason I suggested 12 g wire was for durability, and compatibility with good connectors that don't cost a lot. Like 4 mm bullets or andersons, or many others.

8 g is overkill for that wattage controller, and the connectors for it cost a bit more. The real losses in power in e bikes occur when you overload them, not when you use 16g wire for a run less than two feet long.

Once you get into the 2000w range and more, hell yeah you need fat wires.
 
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