Guru
Joined: 26/09/2020
Location: AustraliaPosts: 642
| Posted: 09:02am 22 Jun 2021 |
Most car alternators have the ability to generate up to around 120 volts if spun fast enough. There was a company once that made an add on box that had a voltage doubler in it, that allowed universal power tools to be run from the car alternator.
They also had a switch that put full 12 volts onto the fields and allowed light welding to be done from the alternator. (the product was called AutoArc from memory)
So getting 48 volts to charge a battery is possible but one would have to be careful with how much current you put out. The alternator could get pretty hot.
I use an alternator to charge batteries on my solar system on the very rare occasions that the sun doesn't shine enough. My setup is crude. It just has a rheostat to adjust the field current. I start the petrol motor, wind the field up and check the current with a clamp meter. I used to set it to 50 amps ( it is an 80 amp alternator) and leave it, whilst checking the batteries regularly.
Yep crude but worked well.
I have not tried it since going over to 24 volts, as I haven't had the need.
Regulating an alternator output can be counter productive as the regulator will keep winding the current down when the battery surface voltage rises. You end up using lots of fuel and making lots of noise without doing much charging.
I am a bit of a keep it as simple as possible type, so manual setting and regular checking works for me.
Pete