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MisterBill2
- Joined Jan 23, 2018
- 27,874
Consider that most 120 volt mains powered sump pumps draw at least 4 amps running, (480 watts), that equates to 40 amps into a 100% efficient 12 volt powered inverter. So that would be quite a draw even at no load, which certainly is what you have with the inverter on but the pump off. So I am guessing that your inverter ON/OFF switch does not directly switch the DC supply lines.
Adding a DPDT, ten amp rated contacts, relay to the inverter load would not be a huge power burden, and then having a second float switch trigger the inverter would make the whole system automatic and not require any intervention to switch it on. The only added expense items would be the relay and the second float switch, that will not need high current contacts.
The relay would be AC powered from the inverter, so the change-over box will only need connections to the mains feed and the inverter output, and the sump pump can plug into it directly. Certainly this would be the cheapest and most reliable scheme.
Adding a DPDT, ten amp rated contacts, relay to the inverter load would not be a huge power burden, and then having a second float switch trigger the inverter would make the whole system automatic and not require any intervention to switch it on. The only added expense items would be the relay and the second float switch, that will not need high current contacts.
The relay would be AC powered from the inverter, so the change-over box will only need connections to the mains feed and the inverter output, and the sump pump can plug into it directly. Certainly this would be the cheapest and most reliable scheme.
