winch box earthing

[guzzla]

had a bit of work done to the truck at the auto electricians and i also got him to wire up the winch control box in its new position and hook up a cabin mounted toggle switch.

i noticed he had no negative grounding to the battery and when i asked him why he said it was alread grounded by being bolted to the chassis.

i havent used it yet as i have no cable but it goes forward n backwards no dramas was just not sure if that goes out the window when its u nder load.

is he right

cheers,
nathan

[-Scott-]

Are you concerned about the earth of your control box, or the cabin switch?

If all the bolted joints between the control box and your battery earth (to the body/chassis) are good (no rust/paint/dirt) then he is correct. You'll get a lower resistance return through the chassis/body than you will through a cable because there's a larger cross sctional area available. (That's average area over the length of the current path, if anybody wants to get picky. )

If in doubt, set your winch running then measure the voltage drop between +ve battery terminal and +ve winch motor terminal - that's your voltage drop through the cable and solenoids. Then measure the voltage drop from -ve battery terminal to -ve winch motor terminal (you should be able to identify it in the winch control box.) You should find the voltage drop in your -ve path is much lower than in your +ve cable.

Cheers,

Scott

[murcod]

Two things would concern me- first, how big is the standard factory earth cable from the battery to the chassis? I'm sure it wasn't designed to handle the sort of currents a winch can draw.

Also, depending on what sort of vehicle it is (ie. separate chassis / body or monocoque construction) could also affect how good the earth circuit is. If it has a chassis, the battery could be earthed to the body and not conduct so well through the mounts to the chassis where the winch is earthed to?

If you run a cable from the negative through to the bolt point where the winch is grounded on the chassis then you've got the best of both worlds and would decrease the resistance/ voltage drop too.

[guzzla]

its an 80s so being full chassis would if be safe to say its earthed sufficiently as is to handle the loads posed on it under full load ?

the winch is bolted to a 12mm 200x150 angle which is bolted between the chassis rails by 5 bolts each side that have nuts welded to the chassis. i feel i have sufficient contact based on whats been said , yes or no ?

regards,
nathan

[BigQQQie]

their should be two earths one firstly that comes from the bottom af the winch motor(heavy cable should go straight to negative battery terminal) the second come from inside the contro box(normally smaller cable 5mm or 6mm and should be earthed onto one of the bolts in the two rods that run across the drum.

[murcod]

i feel i have sufficient contact based on whats been said , yes or no ?

The winch to chassis contact sounds fine, but that's only part of the circuit.

Load it up and check for voltage drops as Scott said- preferably between the negative battery terminal and winch motor negative (if it's accessible?)

Check how big is the earth cable from your battery negative to the body/ chassis (and which it goes to?) See if that cable gets warm when winching.

[guzzla]

thanks guys, i believe the sparky was on the right track but it may just be easier to have the cable put back on just to be sure to be sure as old irish paddy says.