I am in the process of building a 18650 based module (7 or 8S 40P) for powering my 24Volt Minnkota Terrova trolling motor. I am planning on building the following but am looking for any suggestions or personal experience from the group which could help me optimize my final design. I am a little concerned with the proper voltage going to the trolling motor. I do not want to fry a $1,500 unit! I have called Minnkota and they were less than helpful. They said the operational voltage was 23.4 to 25.6 volts however they would not tell me what safety factors they have built into the circuitry. I suspect there is a larger range.
- Should I do a 7S or 8S
- I am planning on skipping the BMS and using a voltage monitor/alarm to indicate low voltage.
- If I go with 8 S I could use 2x4S modules to enable charging with a hobby charger.
- If 8S is used the voltage will be too high according to Minnkota. My thought was to add a 60 AMP PWM on the output. Will the PWM be "too dirty" to power the TERROVA which has its own PWM?
- Will a PWM work if the actual voltage drops below the setting it is at - basically just letting pass through voltage through without reduction?
Any thoughts and experiences are greatly appreciated.