(ET) Watts/ Amps to HP

["Max Hall" <maxo iname com>]

Simply:

1 hp = 746 W
power (in watts) = (current [in amps])*(voltage [in volts])

example: a 36v electrak running at 100A is delivering 3600W, or 4.8 hp.
NOTE: there are ineffeiciencies to worry about, too.

Rule of thumb, each hp from an electric motors rating is worth about three
hp of an ICE's rating. Therefore, if you want to replace a 9hp gas motor,
you would only need a 3hp (or ~2200W) electric motor. Another typical rule:
electric motors are about 80% efficient

There are lots of caveats and exceptions, but these are good starting
points.


-----Original Message-----
From: Jeff Tickner <jefft softlanding com>
To: <elec-trak cosmos5 phy tufts edu>
Date: Friday, June 04, 1999 8:21 AM
Subject: RE: (ET) newbie


>These sound like valid points to me (for what that's worth). The
>hydrostatic transmission is finned and has a fan on the drive pulley for
>cooling. That means parasitic power losses given off as heat. The power
>issue seems valid also for snowblowing. Any sources for cheap and/or used
>5HP+ wound field or permag motors? Also, what is the general rule for
>converting Amps or Watts to HP?
>
>Since I already own the tractor and there is something wrong with the
>engine I want to pursue this. Besides, my push mower isn't going to work
>well for snow :)
>
>
>Jeff,
>    Here's my two cents on your conversion.
>    1. I think  you'd be best served with a wound field or permag motor
>which you could run as a single speed motor.
>    2.  You may not be happy with the efficiency of the hydrostatic
>transaxle.
>    4.  Except for light use the 3 hp golf cart motor will probably be too
>light..  So long as the batteries have excess capacity for the actual lawn
>I mow, I'd
>accept the losses in the hydrostatic transmission.  The only problem is
>finding a good used cheap hydrostatic transmission and E15 motor.
>    So good luck with however you do your conversion.
>
>Steve Naugler
>
>