Did you ever mention things getting warm, thats all wasted power. And if you have a esc that supports regen you can charge your battery while braking (a bit). I would say you’re totally fine if you go riding your board when it’s on (just don’t charge your battery totally full before you do that).
i feel like this is a great definitive outline from rew on vedder.se:
[quote=“rew”]There simply isn’t hardware to “dissipate heat”. So that won’t happen.
I have a 4700uF capacitor on the input. At 50V it holds: 0.5 . C . U^2 = .5 * 4.7mF * 2500V^2 = 5.8J of energy. That would be when going from 0 to 50V, it is a little less if say you go from 12V to 50V. 12V is about the minimum operating voltage for the VESC.
Anyway, braking at 300W, would give you the ability to brake for about 20ms before the capacitor exceeds 50V. If you’ve set a “battery max” the VESC will stop trying to brake, but the back-EMF back-feeding into the capacitor cannot be prevented. This is a “no-op” as long as your speed is below the 50V theoretical max speed. So for example, my bike goes 1 km/h for every volt of battery voltage. So if I join the tour-de-france going down a mountain, the VESC will stop trying to brake at say the max voltage of my battery say 30V. This can happen at 20km/h. Then when I hit 30km/h the motor will feed the bus voltage without the VESC’s consent. If there is no battery and just a cap it the speed will rise to 60km/h and the bus voltage will be pushed over the 60V-and-more limits of various components on the VESC. At less than 70V, the mosfets will start to conduct even when driven “OFF”. Once there is a path, significant power from the mechanical system will be put into the mosfets. These mosfets are very sturdy and the manufacturer has specified how long this can go on… The taken energy can be a maximum of 0.5 to 1J (“Single pulse”). This will last you less than a milisecond at those speeds.
So: If the battery voltage goes above max, the VESC will stop helping with braking. If your speed then goes above the theoretical speed for 60V batteries, the VESC will die without warning.
When scaling mountains, start with a full battery at the bottom, ride the thing to the top. That guarantees “space” in the battery for the regenerated energy. Do not go faster than the theoretical speed for 60V batteries. Have a mechanical brake to dissipate energy if you want to.[/quote]
So, i read this as “don’t brake fully charged” - there is almost no leeway (a few ms) and after that your brakes will stop and your VESC will fry. And definitely don’t ride w/ no batteries, or powered off.
HTH!
This:
I would put a switch on the positive leg going from the esc to the motor. this will mean that the motor will generate a prety high voltage, but no current. (do not touch! more info: Windy Nation Inc) Just turn the switch off when you want to ride in passive mode and back on when you want some assistance.