Do electric cars have brakes?
01-09-2016, 10:42 AM
#26
Many RCs such as 4wd electric buggies that utilize a center differential can be fitted with a disc brake and servo to control it. But why? The ESC is designed with braking in mind as well as acceleration. It is a function that usually will not cause ESC failure or overheating. Your battery discharge rate and cel number is what really ends up creating heat issues with motors and ESC's. Correct me if I am wrong here my friends.
But before you go switching to mechanical brakes you need to consider how much heat you're generating during acceleration. When I setup a vehicle I drive it hard, harder than usual. Lots of hard acceleration to top speed immediately followed by hard braking to a stop. Doing so ensures the motor will see maximum load and maximum temps. So of course temps will be lower during more normal driving without those repeated hard launches and braking. Want to test how much of difference mechanical brakes might make? Find a spot with enough room you can get to top speed and make turns at high speed. You want to make repeated high speed passes using as little brake as possible when turning around. Coasting before turning around is fine, just turn around as quick as possible, we want hard acceleration to top speed and multiple back to back runs to see how hot the motor gets just under acceleration.
If your temps are too high with normal driving and the above test then the load is too high and temps may not be lowered much if at all by adding mechanical brakes. Load is what determines motor temps. Load is determined by vehicle weight, gearing, aero, surface being run on etc. Geared for 40mph on 4s, temps should be similar geared for 40mph on 5s because the load is the same. Shedding weight and lowering top speed through gearing are the only ways to decrease the load on the motor. Only other option is a heatsink/fan on the motor or to get a bigger and/or more powerful motor that can handle the load.
01-14-2016, 02:24 PM
#28
It's true, there is regenerative braking, mostly because the current generated under braking has to go somewhere otherwise the esc would have to absorb it somehow. Pretty sure it's discussed on the 1st page where this thread was resurrected more than once since 2008 lol.
01-14-2016, 05:15 PM
#29
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Ah yes, just found some talk of that. Didn't read the whole thing before posting, should've though... lol
It's true, there is regenerative braking, mostly because the current generated under braking has to go somewhere otherwise the esc would have to absorb it somehow. Pretty sure it's discussed on the 1st page where this thread was resurrected more than once since 2008 lol.
