Winch Grounding?

[NatersXJ6]

Hi. In very broad terms, do most electric winches ground through their mounting bolts? I have a Warn M8000 in my Jeep, running separate battery cables all the way back to the battery. The battery is a dual terminal marine style and the winch wiring is separate from the rest of the vehicle wiring. I noticed that the vehicle still has power with the vehicle negative disconnected but the winch negative still connected. Is this normal? I’m guessing yes, but for some reason, it surprised me.

 

[john61ct]

There really is no Earth Ground.

The Vehicle Common is usually in the Negative Return path for all DC circuits even when there is a complete round trip circuit - as there should be - between a power source and the loads it is feeding.

A given power source can often be completely isolated, as can a given load device, for safety when maintenance is being performed, or if needed in emergencies.

But usually there are multiple paths back to Vehicle Common - what they call "Chassis Ground" as well as power negative - when any systems are actually in operation.

 

[DaveInDenver]

I have a Warn XD9000 and there's a lug on the motor for the return/negative/ground supply cable back to the battery. So yes, your vehicle chassis negatives may find a sneak path back to the battery through the body or frame through the bumper, motor and winch housing. It's not a solid path for anything except the winch motor, though, so what might seem to work for perhaps a dome light or radio probably will be poor (excessive voltage drop) for the starter or headlights that may not work at all.

 

[luthj]

Most winches use relays to reverse the motor. So the motor casing itself is not connected to the negative. Though some may opt to bond the negative to the winch body at the box. I wouldn't rely on such a bonding to carry several hundred amps though.

Edit: I forgot these are series wound, disregard.

 

[DaveInDenver]

Most winches use relays to reverse the motor. So the motor casing itself is not connected to the negative. Though some may opt to bond the negative to the winch body at the box. I wouldn't rely on such a bonding to carry several hundred amps though.

The field winding polarity is flipped through the solenoids or contactor and the armature winding is energized the same polarity regardless. Both windings return large current through the lug on the bottom of the motor back to the battery. If that has changed recently or isn't industry standard then I stand corrected. But AFAIK Warns are still built that way.



The lug on the bottom of the motor isn't insulated from the motor case. The winch doesn't float electrically from the chassis, although it isn't necessarily well bonded and can't be relied upon as a primary vehicle-wide ground because there can be non-trivial resistance through the motor case -> winch frame -> mount -> chassis.

ETA: Forgot to mention, the small wire from the control box to the winch motor is the return for the control electronics.

 

[Happy Joe]

I am a HUGE fan of running a heavier than adequate (usually 00 welding cable; its what I have) ground wire from the battery to the appropriate ground lug on winches (Have actually gotten some great deals on perfectly good used winches that did not work, due to poor grounding).

BTW I also, typically run a separate heavy gauge (#10 minimum with small alternators) alternator frame ground to the main block grounding post/point (which typically also has the battery, and chassis, ground attached.

Enjoy!