voltage or current sensing alternator regulators

Can't see why. For example let's say you have a 100A alternator and the winch is drawing 300A.

Then 100A from the alternator and 200A from the battery.

Cheers

This is the best way to winch.....the alt actually allows for more volts (14 vs 12.7)
Now more volts means less amps to the winch, which inturn means faster spool and less heat buildup in winch.
HOWEVER nothing comes for nothing here, the extra amps (flow of power) that the alt has to produce causes it to heat up...really hot!
So the best way to do it is run motor, winch for a minute at a time and give it a rest for a minute...lets everything stay cool and stablise again.
(If the tidewas coming in, id keep winching though :-) )

Andrew

Yes the alternator will take some of the load off the battery.

Also :- More volts means more current as the winch will have the same resistance.
current = volts / resistance.
The winch MAY get hotter as it has more power available. ;)

Good question Skinnydog.

Unless the alternator and it's associated rectifying diodes etc. has some form of over current protection (does anyone know if they usually do?) built in then the answer must be; yes, it can damage the alternator/charging system.

Let's say the winch draws 300A under load. When the winch draws power that load will be shared between the battery and the alternator (the only sources of power available). The proportion of the 300A each supplies will be according to it's internal impedance. If you commence winching with a good battery then chances are the battery will have a lower internal impedance than the charging system and thus will supply the majority of the current. As you continue to winch a fairly complex situation will develop where the battery charge drops (hence it's internal impedance rises) and it is able to supply less current. To make up the difference the alternator now needs to supply more current. If you continue winching for long enough the battery will be able to supply very little of the 300A and the alternator will be working flat out trying to supply as much as it can of the balance. It's at this point when there is a danger of damage to the charging system by overloading the alternator.

The only solution (as someone mentioned) is to winch for a minute and rest for a minute - how effective that will be depends upon a number of unpredictable variables but it probably gives you the best chance of succeeding. Also ensure your battery is in excellent condition before setting out on a trip where you may need to winch.

Mike Harding

mike_harding@fastmail.fm