On Sun, 04 Apr 2004 15:23:39 GMT, Gualtier Malde
wrote:

Wayne.B wrote:
On Sat, 03 Apr 2004 19:40:59 GMT, Gualtier Malde
wrote:

1500 Watts? Are you sure? The formula P=IE, or I=P/E = I=1500/12=125Amps.
Thats a whole lot of juice. Do you have water cooled jacketed batteries?


========================================

Why is a 125 amp intermittent load a problem?

Most engine starters draw that much or more.

Right, but they operate only for a reasonably short time. I don't know - I was
just impressed by the fact that 125 amps is a helluva load for deep cycle
batteries, which have endurance.

But admittedly not, at first, for the 4D and 8D batteries Mr. Locke has. Except
that cranking amps are not supposed to be delivered for what certainly must be
several minutes of work. I haven't any figures on it, but would be concerned
about how long a sustained draw could be maintained, repeatedly, on D series
storage batteries before they died.

I think that if I needed a winch with that much power I'd look into hydraulic
ones, or those operated with 120vAC.

Those high power DC motors draw DC amps based on the load you put on
them. Anchor windlasses are another example. They are capable of short
bursts of high power and long operation (well, minutes) at low power.
Heat builds up in the motor, the wiring, and (hopefully) the circuit
breaker which should be carefully matched with the motor so the
breaker cuts out before the motor melts down.

Motors on winches look to be about 4.5 inch diameter and 8 inches
long. 1500 watts is about 2 horsepower, and in a package that small it
can't run very long at full power without water cooling the motor, let
alone the batteries.

Specs are complicated. The Harken 44 winch spec in the West Marine
catalog says "14 amps free load, 160 amps stall" and the Harken web
spec sheet ffor the 44 says "600 watts, 12 volts, 100 amps." Obviously
the spec sheets and catalog are oversimplified because none of that
math works out.

In the meantime we don't have the data to be certain about anything.
When I get more details I'll post them here.