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How to choose what wire to get

I'm not sure how to chose what gauge of wire I need. I'm wiring two 12 V batteries in series with a 24 V 450 W motor, and a controller, and a throttle. So if I'm looking at having 450 W at 24 V that would be 18.75 A of current so that means I need 9 gauge wire since it has a max power transmission of 19 A, or should i go up to 8 to be safe? Do I need the same gauge wire for connecting the controller to the throttle and the brake lever and what not? can someone explain how I should decide this?

Most 24 Volt 450 Watt electric scooters and bikes use 12 gauge wire. You could use 10 gauge wire just to be on the safe side. You definitely do not need to use 9 or 8 gauge wire.

Our wire gauge selection chart recommends 12 gauge wire for 24 Volt motors between 450-600 Watts. Here is a link to our wire gauge and fuse selection chart:

Please let me know if you have any further questions.

14 gauge COPPER wire is good for 15 amp, 12 gauge is 20 amp, and 10 gauge is 30 amp. For aluminum 12 gauge is 15 amp. The heavier gauge wire will have less resistance, thus less voltage loss. On short runs like on scooters (4 ft and less) there should not be much loss though. But this is why people burn out dills, saws, weed wackers, etc. when using 100 foot or more extension cords rated 16 or 18 gauge. When a motor with a specific voltage rating is run at much less voltage, it has to work harder to try and run, and gets hot and burns out, I assume that is why most of these controllers shut of when the voltage gets to 20.5 volts on a 24 volt system for example.
Hi Linzo, your wire rating specifications will definitely work for electric scooters and bikes however such thick gauges of wire are not necessary with the short runs of wire that most electric scooters and bikes have. There is nothing wrong with using thicker than necessary wire though, and I am a big fan of overbuilding electrical circuits for reliability and prevention of power loss.

The reason most 24 Volt controllers shut down when the Voltage reaches 20.5 Volts is to protect the battery pack from being undercharged. If the controller allowed the battery pack to run under 20.5 Volts it would damage the batteries.

Since the length of the wire significantly affects its power rating we now have an online Wire Gauge Calculator which can calculate a wire's power rating using the following parameters: Acceptable Power Loss, DC Volts, Amps, and Length of Wire

Using this calculator is the most accurate way to determine the minimum wire size necessary for an application.

Our online Wire Gauge Calculator is available at this link:

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