disconnect the battery.....

[Shield Arc]

In 2004 I bought an F-550 cab & chassis, built a 14-foot flatbed dump for it. In the up fitter's manual it said to disconnect both batteries before doing any welding. 2007 I sold it and bought a Dodge cab & chassis, bought an aluminum flatbed for it, but made the bumper, and a sub frame to attach the flatbed to the frame of the truck, again in the up fitter's manual it said to disconnect both batteries, which I did.
Now for the catch, I've done a few little welding projects on my JD tractor, never once disconnected the battery. Couple years ago I ran out of fuel, but the gauge said 3/4 of a tank! Circuit board in the dash went out. John Deere wants a $1,000.00 to replace, (yeah like that is going to happen)! So the question is, did I burn this board out by not disconnecting the battery, or just one of those things?

 

[DarkBlack]

Glad I don't buy deer- $1,000 for a dash circuit board ????
Millions of people have electronics fail, new and old- who don't weld. Amazing ehh??

 

[Shield Arc]

$1,000 for a dash circuit board ????

Yeah I about fell over!
When ever I'm welding on a vehicle, machinery, or any kind of equipment I keep the ground clamp as close as possible. I just didn't think it would hurt my tractor, but who's to say that is what happened?:confused3:

 

[pipefitter]

My curiosity was whether or not there were any electronics I would damage when I do this weld. As I said, I was told to unhook the battery when welding on a vehicle with a computer, and wondered if it was necessary on my tractor. Thanks for all the responses. BTW, that's a great looking headache rack, Shield Arc!

 

[Shield Arc]

BTW, that's a great looking headache rack, Shield Arc!

Thank you!
Would you believe when I got through with that truck, adding the hoist, hydraulic pump, tool boxes, and bumper, I added 1-ton to that truck? All it did was make it ride a little better.:laughing:
Couldn't find any pictures of the hoist, but here is one of the bumper I built.

 

[CNC Dan]

give the choice.. i'd disconnect hot before ground....

Cuts off power just the same, but if your wrench hits the body or frame you can get a powerfull arc. That's why they always say to disconnect the neg. terminal.

 

[DarkBlack]

I was waiting for someone to call BS on my #19 post, No doubters?

 

[Soundguy]

Cuts off power just the same, but if your wrench hits the body or frame you can get a powerfull arc. That's why they always say to disconnect the neg. terminal.

if I'm removing the battery, I'll disconnect the neg first, to prevent that.

if I'm not removing the battery.. i might like everything in circuit still grounded..

 

[Baby Grand]

Come to think of it, In the very unlikely event that things were done wrong to allow the welder to possibly cause issues with either the expensive electronics, or the battery, I can think of some situations where the electronics would actually be more protected by leaving the battery connected.

I was waiting for someone to call BS on my #19 post, No doubters?

Okay - I'll play devil's advocate.
Just curious how you figure that?

 

[DarkBlack]

Glad you asked!
Without getting technical I think the easiest way to explain it, is to say that the battery is parallel to all the exposed loads. Since the electronics are designed to run from the battery's voltage range, any outside influence over that range will be partialy buffered by the battery's tendency to maintain it's voltage and absorb current from higher voltages. That protection would end, of coures as soon as the fuse blew.

Here's just one example: You do everything wrong-you leave the keys on so your expensive ECU is connected to frame ground ( including all sensors ) and through the ignition switch and the fuse to the battery. You connect your welder ground to one end of the tractorand you bring the mig/stick to the other end. Now to damage the ECU you need to send current through it, so you start welding where some + wires are nearby, and you burn through the wire coating of the power lead of the ECU.
If you had the battery disconnected you now are probably puting somewhere around 20 volts on your expensive device that is destroyed above 16-18 volts. But if you had the battery still connected there would be a paralel path through the fuse to the battery. The battery would have drawn some current before the fuse blew, lowering the voltage because of the added current to the battery.