Re: Alternators

[tsm1@domain.elided (Tom Mandera)]

>charge the battery and not damage electrical systems.  Just an aside... if
>there were no voltage regulator, a modern alternator could easily hit 140
>volts!  Ouch.

It's this characteristic that's used in the manufactured (Premier Power)
on-board welders, as well as some DIY plans I've seen.

In the mfg case, a modified alternator is used.  When welding, the
alternator is unregulated, putting out John's 140volts (or whatever it is..
substantially over 12v anyhow).  But once the juice passes the welding lead
attachments (or is controlled via the control box), it's regulated back down
to 13.8V for comsumption by the car's electrical system.

The home-brew variation on this that I've seen involves modification of the
diodes in the alterntor, and then removal of the voltage regulator.  Run the
alternator "wide open".. for maximum welding voltage.

One of these days, when I run out of projects, I'd like to draw the circuit
out that would allow me to take a 90+ amp alternator, make the proper
modifications to weld with it, and at the same time have an external voltage
regulator that can be used to switch the alternator into the car's
electrical system, regulated, or out of the electrical system unregulated
(for welding).

-Tom Mandera, Helena MT
http://www.tmcom.com/~tsm1/scout
'72 and '77 Scout IIs - Street/trail
'77/78 - Street/Race when I get done...