[Badfish740]

I figured that maybe some of the regulars in the generator forum could advise on this. Apparently (if you're an electronics whiz) it's fairly easy to get an automotive alternator to put out as much as 120VDC by modifying the voltage regulator. This could be very useful for charging large banks (48V, etc...) of batteries via an alternator coupled to a small engine. Has anyone seen a good FAQ out there of how to do this? I just don't know enough about resistors, diodes, etc...to make sense of it all without pictures or very detailed step by step instructions.

 

[maxmetal]

I figured that maybe some of the regulars in the generator forum could advise on this. Apparently (if you're an electronics whiz) it's fairly easy to get an automotive alternator to put out as much as 120VDC by modifying the voltage regulator. This could be very useful for charging large banks (48V, etc...) of batteries via an alternator coupled to a small engine. Has anyone seen a good FAQ out there of how to do this? I just don't know enough about resistors, diodes, etc...to make sense of it all without pictures or very detailed step by step instructions.

I agree this could be a handy capability and a good thing to know how to do. And if we knew how to do it for 48 vdc, we'd know how to do it for 24 vdc or any other voltage.

Probably, all it takes is different voltage regulator chips inside the regulator. But of course, they are always potted.

I would imagine that the current carrying capability could be an issue. If you have a 100 amp 12 vdc automotive alternator, then you would only have 10 amps at 120 vdc (Ohm's Law) since the safe, continuous power generating capability of any particular unit is fixed.

While I am not an electronics expert, I can think of two things to help circle in on it.

The first would be to look up generic voltage regulators. I am sure they are available in all voltages and power handling capabilities.

The second would be to look up voltage regulator circuits to find out if it is as simple as swapping out a voltage regulator chip with a different one and adding a big heat sink. Or maybe it is easier than that, maybe some resistor gets changed to tell the VR chip to regulate to a higher voltage.

This is an extremely interesting idea and I hope some others chime in.

 

[Tractor-Holic]

You could just wait a few more years--I read awhile back that they are planning to change new vehicles to a higher voltage system,and I think 48 volts was the target..

One prototype I saw in a magazine however,showed the alternator and starter being a combined unit,made around the flywheel,much like the charging system on many small engines..(can you say "nightmare to service" ? )..

I would say it would be easier to boost a 24V alternator from a semi truck up to 48 volts,than a 12V car or truck one..or get more amps at least--its is possible to get up to 120+ volts from a 12V alternator,but at the penalty of losing amperage..but I've seen car ones used to weld with 1/8" rods,so they must be able to put out a healthy amount..

If you google "Alternator Secrets" you should be able to find a reprint from a Lindsay publications book that explains how to get more voltage from car alternaters..

 

[steddy]

Another possibilty-
A voltage regulator is basically a zener diode, if I re,pmember my electronics classes well enough (I probably don't....). If you find an alternator that you can remove the factory regulator, or possibly an alternator with no factory regulator, you could basically make your own VR from something like this. This would be the 30 volt version, pretty close to what you'd need. I've got to think a 48v wouldn't be far off. Otherwise, aren't some golf carts and such 48v? Possibly run the charger off an alternator's AC power and let the charger convert the voltage?

Gems Single Channel Zener Barrier Shunt Diode 113000 250V 30VDC 330 ? Ohms New | eBay