This is an excellent solution to this problem and nice easy idea to add the pre charge button to my MNDC 250 breaker box right above the 250 amp breaker. Thanks !
For those of us not electrical engineers, what is the formula to calculate this pre-charge resistor for 12 or 24 volt banks. Does the inverter size also play into the calculation?
There is not much science behind it, 1A will be enough to quickly precharge inverter and not cause any sparks. You'll need 12 Ohms (for 12v) and 24 Ohms (for 24V) resistors. R = V/I Ohms = Voltage / Current
@@SolarEngineering Chargery will be releasing the new DCC Contactor wich has a pre-charge circuit and more later this week. See here for a teaser: diysolarforum.com/threads/chargery-bms-news-update-july-27-2020.10175/ These effectvely replace the delay board, plus. I believe the pricing will be somewhere around $100 USD for the 300A DCC. BTW, this also incorporates an optocoupler idea which allows for One DCC in a Common-Port config, so you only need the ONE Relay instead of two.
