openinverter forum

Hi everybody, Can DC energy produced with a 12 volt alternator be converted to AC energy with an inverter? The alternator is variable speed. The operating voltage is fixed at 13.5 volts and the current produced varies between 45-110A depending on the alternator speed.

I want to convert a smart off-grid 1200Watt hybrid inverter into a standalone device for alternator, solar power and shore charging needed in a caravan or boat. Can the AC energy from this inverter connected to the alternator be used to feed the hybrid inverter's mains AC input?

You may suggest charging the batteries directly with the alternator. Since Lifepo4 batteries force the alternator to work at full capacity, the alternator overheats and burns out in a short time. Another reason to look for a different way to charge the batteries with the alternator is that the BMS-induced high charge voltage protection circuit inside the Lifepo4 batteries cuts the charge independently. In the meantime, it is aimed to stop the charging in a controlled manner in order to prevent damages caused by the overvoltage occurring in the alternator.

It doesn't quite work like that, you have to have a battery in the alternator circuit, it's there to smooth out the current output and help stop any surges in current from the alternator.
If you end up running a vehicle with no battery the alternator doesn't get a good reference of system voltage and fails very quickly, would imagine it's the same if you hooked it directly to the inverter

Yes; you need a battery doesn't need tobe a big one. Maybe now a days super caps would be sufficient?

AltInv wrote: ↑Sat Oct 29, 2022 9:30 am Can DC energy produced with a 12 volt alternator be converted to AC energy with an inverter? The alternator is variable speed. The operating voltage is fixed at 13.5 volts and the current produced varies between 45-110A depending on the alternator speed.

Well yes... especially if the alternator output AC without the rectifier present. Unless is a generator-dynamo design I guess where only DC is output without any regulator or rectifier circuitry parts.

So figure in theory, a basic transformer would convert when wound correctly the say for example 13.5VAC @ 100A to 135VAC @ 10A.

AltInv wrote: ↑Sat Oct 29, 2022 9:30 am Since Lifepo4 batteries force the alternator to work at full capacity, the alternator overheats and burns out in a short time.

Would some sort of current limiting circuit help prevent the alternator overloading?

Like something to current limit alone or sense like a thermal cutoff switch or something else probably not needed with a relay or for higher current isolation relay to cutoff?