power wire

[JohnnieB]

It boils down to Peak amps vs Continuous amps. Then you have to consider the fact that the Amp ratings are very, very conservative.

The only times the high current cables will be carrying the max amps that the controller will pass is when the motor is stalled, or during hard acceleration, or climbing steep hills, or towing/hauling heavy loads. Other than that, they will typically be carrying someplace in the 50A to 75A range.

The stock cables in older carts are 6Ga, which is marginal to say the least, but sufficient enough to be accepted by the lawyers and accountants that weigh cost vs liability.

Replacement cables should be 4Ga (or heavier) for 400A controllers and below and 2Ga (or heavier) for 500A and above.
How big is too big is more a matter of flexibility than ampacity.

Basically, any cable that gets more than warm to the touch (about 10°F above ambient air temperature) is either defective or too small for the application and needs to be fixed or replace with a heavier gauge.

FWIW: I run 2Ga cables and have a 500A controller feeding 42V to a motor that is rated at 11.8HP at 48V and there is very little level ground in this area, so my cart is usually climbing hills or coasting down them with regen braking. The motor temperature typically climbs into the 180 °F to 200°F range, but the cables seldom climb above ambient air temperature.

[wards75]

Thanks JohnnieB for the explanation!

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[yurtle]

Further, ampacity for a conductor is affected by its insulation and installation. Is it inside a "small" conduit, where heat dissipation is limited or "out in the open". Is it a single conductor or a part of a multi-conductor cable.

[simple man]

Originally Posted by wards75

Just bumping this up as I am curious about this specific question.

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I looked up 6ga wire (stock size for EZGO) and it is rated at 75amps at 90°C. The stock controller is 275 amps. Does this give you an idea? Remember that the cart is not using the full available capacity of the controller all the time! If I recall right, steady cruise on pavement uses 50-60amps.

[yurtle]

And generally a buggy would carry a max of two riders, and have plenty of time to cool off, between holes.

Like many things electrical, their ratings can be exceeded, as long as they have time to cool off. Thus the peak instantaneous is "less" important than the average.

[eflyguy]

The controller rating doesn't mean it will provide that current - it can only provide as much current as the motor is drawing, which is pretty much fixed by the windings, and the load at that moment.

A higher-current controller simply has a lower resistance, so operates more efficiently - less loss at the controller.
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