Motor Windings

[Deleted member 36384]

Hi,

I have refurbished an old Simpson Lawrence / Francis Marine windlass. It has a 24V motor in it. By chance I picked up for spares or repairs the same winch except it is not known what voltage the motor is.

My winch is designated SL400 but I do not know if this means 400W, there is an SL800 winch as well and it looks identical to the SL400 based on viewing pictures, not actually checking.

My winch motor, the SL400 24V appears to be smaller than the spares and repair winch motor? What I am trying to understand is would the 12V motor be larger because the wire has to be thicker? For 24V 800W motor would it it be physically larger, more windings (assuming the 800 is double the power rating)? In the absence of any labels, is there any way to tell what voltage the motor is?

If the spares and repair motor is 800W and 24V then I would swap over as the mountings are identical.

The winch was put on the boat in 1974 and it hauls up a 80m of 10mm chain and a 60lb CQR adequately.

Any information on motor windings to gain some information would be appreciated.

Thanks,

BlowingOldBoots

 

[Lon nan Gruagach]

Motor size is mostly governed by power.
A lower voltage version would be the same size since, whilst the windings would be thicker, there would be fewer of them.
For half the voltage you would wing wire with square root of 2 * cross-sectional area but with half the windings.

edit: corrected some maths.

 

[superheat6k]

The pure resistance of the 12v motor will be considerably lower, but you will need an accurate low ohm measuring meter to determine the difference accurately, e.g. the low ohms setting on a 1000v megger normally has the ohms reading to 2 decimal points and can be accurately read to one decimal point.

Be aware also a dirty / worn commutator can affect pure resistance measurements made with a low voltage ohmmeter. The difference in pure electrical resistance may not vary in proportion to the voltage change, because the motor resistance in motion is an impedance which is a combination of the pure electrical resistance and inductive reactance.

 

[William_H]

If you have a multimeter with 20 amp range then try powering up each motor with no load from 12v. The 24v motor will draw less current than a 12v motor. If you don't have a meter with 20amp range or if that is not enough, power each motor via a piece (try 2m) of SS rigging wire or a piece of iron fence wire and connect the meter on 200mv range across the wire. ie the wire is used as a shunt, uncalibrated but good for comparison. Although one is rated at twice the power no load current should be similar fro same voltage rating. olewill

 

[<152587>]

From memory which is not good these days, possibly 2 sorts of motors were fitted. the smaller motor had external remote mounted solenoids, whilst the larger motor had the solenoid incorporated in the end cover. Both had 3 large (M8) terminals but the latter only utilised 2 terminals. The other giveaway is the additional small wires on the latter to energise the enclosed solenoids. Italian manufacture I think.