Winches and pumps

I’m not really afraid of the smaller wiring projects, but this one has me a little nervous. Basically I’m wondering if it’s bad to direct connect both a winch as well as a air compressor to the battery, they have in line fuses.
Obv they won’t be being used at the same time, unless there is some sort of f-up.

 

Why would that be bad?

 

I don’t know. That’s why I’m asking. Just seems a little like this

 

Haha, nice pic. That is probably the best way from a electrical isolation standpoint. As long as they have some sort of circuit protection then direct to battery is no problem. I think most winch manufacturers recommend that they are connected directly to the battery.

 

Just make sure all the wiring is secured so it doesn't wear through from vibration on adjacent components and your fuses/breakers are installed properly it should be good.

 

What's your concern? You can wire the air compressor direct to the battery with with an inline fuse and that makes the whole circuit totally protected. For the winch I used this kit to install a switch to kill power to the winch so there isn't juice to it all the time.

$108 WARN 62132 Power Interrupt Kit with Battery Lead, Hardware, Solenoid, Switch and Wiring

https://www.amazon.com/gp/product/B000CQFVN8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8

 

No issue with the air compressor. But good luck finding a reliable fuse big enough to protect a winch. Thats why most folks go direct to the battery without any overcurrent device for winches

 

I like that switch. Thanks for the info. Also I’m still laughing about twat waffles

I’d be tearing apart the front end right now but my winch is in transit someplace. Guess I’ll start with the compressor then

 

No reason you can't do them separately. Like @SR-71A said you won't find an inline fuse big enough for the winch, but the switch has given me some peace of mind that there isn't 2AWG wires hot upfront in case of an accident.

 

Larger and smaller sizes of fuses and breakers are available.

400A Fuse

$5 Baomain ANL-400A Electrical Protection ANL Fuse 400 Amp 2 Pack

https://www.amazon.ca/Baomain-ANL-400A-Electrical-Protection-Fuse/dp/B01MYPSLRV

400A Breaker

400-AMP 12-VOLT CAR AUDIO CIRCUIT BREAKER MANUAL POWER FUSE RESET. GETWIREDUSA #148-400A

https://www.amazon.ca/400-AMP-12-VOLT-CIRCUIT-GETWIREDUSA-148-400A/dp/B019GHCGOK

If you have no protection on the circuit ... and a wire rubs through the insulation... you will have a fire.

If you have just a switch,
and the main wire is damaged and you have a dead short... You will have upto/over (depending on battery/ wire size/ length etc) 1000A flowing of fault current.

Well drop some #2 bare copper across some battery terminals (from a VERY safe long distance, ) and see what happens.... (don't do it)
At best you have a huge bang and the wire blows off the terminals spraying plasma and hot wire,
At worst the battery "explodes"
A switch may weld itself closed during a fault,
and even if you had not jumped 10 feet away from the bang and sparks you may not be able to open the circuit again even if it was not heating up and melting with all the fault current.

For my 10K winch, I use a 250A breaker.
Yes at a full 10K load it will draw over 250A.
But the trip curve on that breaker shows that it would take 300 seconds before it would trip at 400 amps.

But here is something most people don't know about breakers, they have what is called a "trip curve "

This isn't the graph from my breaker, but an example (different for each brand and model)

This 100A breaker could be loaded to 300A and it would take 5-13 Seconds before it will trip.
Dead short would be under a second.

 

Can you explain the part I made bold a little more? You mean the wire downstream of the switch between the switch and the winch? That event would happen in the case of the short happening, and the switch being turned on, correct?

 

Any type of short will draw an extremely high current until something happens to clear the fault. That "something" will be 1) battery exploding, 2) wire burning into or 3) Fuse protection device clearing.

 

I’m curious as well because if the switch is off, that doesn’t make sense.

 

Guess that depends on where the switch is and where the short happens. But yeah - switch ON. If you use a switch?

EDIT: Wait, Are we talking Battery Switch? Or Winch Controls?

 

I put a (600 amp) disconnect between my winch and battery. Its a “Blue Seas” marine diesel disconnect.

 

I’m talking a winch control solenoid switch. I have a short (~4”) 2AWG wire to the solenoid then everything downstream of that isn’t hot until I turn on the switch. Main thinking is in case of an accident the live wires upfront won’t be hot.

 

A lot of people will put a simple ON-OFF 500a switch on the positive cable of a winch. They’ll put it near the battery. That way there’s not a long, hot lead at the front of your truck for every day driving.

What littlefish and I are clarifying is that if the switch is OFF, then there is no risk of it shorting out past the switch.

 

OK. Just making sure that someone didn't think that everything was safe as long as the winch wasn't in operation?

A switch is nice to have. But, considering the cost of each, I would recommend a fuse only. Because A) you might forget to turn the switch OFF. And B) although only remotely, you could have an issue while the winch IS in operation. When the sparks start flying, it's very hard to reach into the fire to throw the switch. I've been there and done that.

 

Ok yes I follow that. Apples to apples the breaker is superior in terms of safety. Your 250A breaker doesn’t trip under a hard pull?

 

Correct, nothing happens if there is a short in the wire after the switch and it is in the OFF position.

If the heavy wire was rubbed through and resting against thin sheet metal when you turn the switch ON, chances are there will be a big bang, some sparks and the thin metal and some of the copper wire will be blown away and clear the fault and you will be able to turn the switch back off (then going to change your underwear).

If you have a heavy gauge wire and it's hard up against some thick steel, if something does not immediately go boom,
you will see that nice big wire start to smoke as the insulation starts burning off the glowing red copper,
there is also a good chance that the amperage from the fault caused an arc inside the switch and welded the contacts closed.

I think the 24F batteries were something like 620 CCA (something like that)

The test specifies that the battery at a temperature of –18°C will deliver a current equal to the Cold Cranking Amps for 30 seconds with the voltage staying above 7.2 volts.

The immediate fault amperage of a fully charged warm battery.... lets say 1000A for an easy number to work with.
Not an exact number, as there are too many variables, but gives an idea of why batteries have to be taken seriously.

Quick youtube video search

Vaporizing a nail.


Batteries have vents to hopefully release over pressure...

So in a best case scenario when your car battery is in a closed fault condition it looks like this...