Murphy's friend
Guru
Joined: 04/10/2019 Location: Australia Posts: 612 
Posted: 04:22pm 05 Feb 2024 



We use a 9:1 secondary to primary turns ratio for a nominal 48V battery bank. All my EG8010 & nano inverters, except the first one (power jack), use that 9:1 ratio  it works.
A tip: when calculating how many turns of wire fit on one layer in the toroid hole the calculated number is not archivable by hand winding. Aim for 10% less turns per layer than the calculated number.
Unless you have a gigantic battery bank it is unlikely you will run your inverter at your full calculated power for long times. So you have some leeway regarding the calculated and available wire size. Use your average longer time Amp load for that. A 45 sq mm primary and 5 sq mm secondary is what I would use. Remember, you also need a choke (or two) that has to carry the full primary current. It's much harder to fit enough turns for a reasonable inductance with big wire sizes on a choke. 