I think this thread has run it's course but one more point I make.
The sense connection can be hooked to a resistor voltage divider to
change the voltage that can be produced. This in turn allows the engine
to turn at any speed high enough to produce the voltage needed. If you
run without a regulator and forget to turn off the field coil your
batteries will drain completely(guess how I know).
Most auto alts won't produce 12v at idle in the standard configuration
and for this reason a larger pulley on the crank should be used. As for
insulation in these units. They are built to withstand a salt spray, as
one would see on salted winter roads. The magnet wire would not be
breached at 100v, I know I abuse such things as I experiment. My poorboy
generator(auto alt connected to lawnmower engine mostly used for battery
charging) has been used to drill holes, saw wood and metal, I have even
hooked the thing to the internal bus of my inverter welder, as well as
most uses involving electric tools when my 2000i generator needed fixed.
Kevin Pemberton
On 09/19/2012 08:18 AM, John Green wrote:
> 1.1. Re: 48v diesel telecommunications standby gen?
> Posted by: "matt elder"mattelderca@yahoo.ca mattelderca
> Date: Tue Sep 18, 2012 5:11 am ((PDT))
> Just a few notes on automotive alternators.
> They can be easily configured to put out any voltage from 12 to 240
> volts. This is simply done by bypassing the regulator, either
> internally or externally depending on the make. Once 12 volts is fed to
> the field windings the voltage output is speed regulated.
> The brushes in these units carry only the small field current and
> sparks and wear are of little concern.
> As to live frames, automotive alternators produce three phase AC which
> is then rectified into DC. By removing the internal rectifiers you
> delete the negative connection to their frame. The rectifiers can be
> setup externally so as to avoid the connection.
> For 48 volt charging there is no need for multiple units, just a single
> unit with the appropriate regulator.
> Newer units are small and efficient although they will not stand up to
> continues heavy use. Alternatives are available in either older more
> robust designs, or newer specialty items. Check into the aftermarket
> car modification market for some really heavy duty units.
> All of this being said, I believe there are far better choices out
> there and there is no need to reinvent the wheel.
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