Re: [electricboats] Battery Fusing

I was not concerned with protecting the battery, I was concerned with protecting the wiring and not causing a fire in the case of a short in the large battery wiring while at the same time allowing for the occasional current spikes that might occur in normal operation.    Are those current spikes limited by the controller programming? 

Your micro controller system sounds intriguing.  It seems like an extension of the controller.  Will the Sevcon try it's best up to some per-programmed limit? Say the 600 amp max capacity of the motor?  Is that something the Sevcon is capable of being programmed for?  Acceleration curves can be programmed into the controller.  Is that the controller not responding as demanded by the throttle input?  If you slam the throttle the controller will ramp up at the programmed acceleration rate, not necessarily as fast as you commanded it to.   But if the load on the motor changes is that a different scenario.   Do acceleration curves still apply? 

Will your emergency override also potentially sacrifice the controller to overload?  And then your in the same position as if you had lost the battery?   How much would the primary wiring be oversized to keep it from being the weak link in an emergency override?   Do monitors like the Vicrtron have programmable settings for high current alarms? 


Dan Pfeiffer

 

On 2021-05-28 7:24 am, Randy Cain wrote:

Dan, your Sevcon will normally try its best to make the motor turn as it's commanded so it could indeed cause an overload of the discharge C-rating and potentially damage the cells. I wouldn't try to protect them with a fuse because it could fail right when you need it. Consider increasing the available C-rating (big cells, paralleled cells or higher C-rated cells). Alternatively (but more complex) would be an active current monitor (shunt + microcontroller) that would monitor battery current and (first) sound an alarm and then (second) disconnect the contactor before damage could occur. This approach would allow an emergency override so the you could sacrifice your batteries to save the boat if the situation demanded it. I'm following this approach in my build using ESP32-based microcontrollers.