Welding on a vehicle

[scrubber3]

I've worked at a very reputable shop for years as a service manager/ technician and during that time I had 3 techs that would weld on a daily basis as well as me and we never did one bit of damage to any electronic device on any vehicle ever. We also never disconnected any battery terminal either. Not sure what the point would be anyway?

 

[deviant _illusion]

I have welded on several vehicles with zero problems but one jeep Cherokee 6 or so years back killed the battery. It's not hard to disconnect a battery so I try to think about it now before welding.

Sent from my ADR6350 using Tapatalk

 

[1stDeuce]

I never disconnect anything either, but I ground right ON what I'm welding on. Not much stray voltage or current that way. Nothing fried yet, but I leave the keys in the ignition a lot and it still hasn't been stolen either... Doesn't mean that either practice is really in my best interest, right?
Chris

 

[HumphreyBear]

The only proof I really have is the incident involving the BMW motorcycle from Long Way Round.

From memory, if it is the bit where they have the cameraman's bike repaired in Mongolia, didn't the welder toast the cable or ABS sensor, not the ECU? The bike started OK and the ECU controlled engine functions were perfectly fine, it just, well, wouldn't brake. I'll have to watch the show again as it has been a few years. The ABS on the R1150GS/As could be twitchy - I had mine knocked out by an errant stone chip.

 

[Conrad_Turbo]

I was thinking about this the other day too...it would almost make more sense to have the ground lead connected to the frame. So if you were doing any welding, say a TIG with high frequency start, any electrical noise transmitted on the ground plane of any nearby electronics will be minimized due to the battery ground being connected. Also you'd want to keep your welding clamp near the area you are welding (obviously). I can only see con's to having the ground of the battery disconnected, no pro's other than wives tales. When soldering electronics you use an ESD mat which is grounded, and you wear a smock that is grounded through your body either via a wrist strap or heel straps (which thus ties you to ground). If you allow the electronics to "float" as opposed to being grounded you risk creating a differential by either pulling it to ground or inducing a positive charge. I'm not an electrical engineer...but I work with a lot of them and in a facility that assembles ESD sensitive electronics. That's just my take on it. I never weld anything that may melt the sheathing on wires so I don't have to worry about the +ve shorting to ground (which would blow a fuse), so I don't bother disconnecting the positive wire either. A note...ECU's (on all the vehicles I've worked with) don't receive power when the car is off, so it's the same as disconnecting the +ve lead on the battery.

 

[truck mechanic]

for got about that, your rite they did fry the bas computor, so thats 2 abs computors that I know of that were fryed by welding.
on a side note, what a dumb idear that the bike doesnt defult to just regular brakes, but you have none at all, just dumb.

From memory, if it is the bit where they have the cameraman's bike repaired in Mongolia, didn't the welder toast the cable or ABS sensor, not the ECU? The bike started OK and the ECU controlled engine functions were perfectly fine, it just, well, wouldn't brake. I'll have to watch the show again as it has been a few years. The ABS on the R1150GS/As could be twitchy - I had mine knocked out by an errant stone chip.

 

[bfdiesel]

A note...ECU's (on all the vehicles I've worked with) don't receive power when the car is off, so it's the same as disconnecting the +ve lead on the battery.

The air gap on the switch is much smaller than that of a disconnected battery.

I have never unhooked a battery on my own vehicles when welding I make sure the ground clamp within 10" of the weld directly attached to one of the pieces being welded. I will however continue to unhook the battery in other peoples vehicles if I am helping them or give those who ask advise to unhook their battery if they are welding on their own stuff. I don't want to be responsible for a blown ECU on some one else's baby, I would feel terrible.

 

[01tundra]

Well being the engineer that I am.....I went ahead and took one for the team and conducted my own experiment last week . I left the battery connected and welded steel plate stiffeners on each side of my frame, and I'm not talking about a few tack welds, I'm talking about burning metal for over an hour. Good news, the truck started right up and is still running fine......so I'm officially calling B.S. on this myth.

 

[LandCruiserPhil]

Well being the engineer that I am.....I went ahead and took one for the team and conducted my own experiment last week . I left the battery connected and welded steel plate stiffeners on each side of my frame, and I'm not talking about a few tack welds, I'm talking about burning metal for over an hour. Good news, the truck started right up and is still running fine......so I'm officially calling B.S. on this myth.

I will now cancell my email to Myth-Busters:sombrero:


You have done a lot of work/welding on your TUndra have you disconnected the battery in the past?

 

[Conrad_Turbo]

The air gap on the switch is much smaller than that of a disconnected battery.

I have never unhooked a battery on my own vehicles when welding I make sure the ground clamp within 10" of the weld directly attached to one of the pieces being welded. I will however continue to unhook the battery in other peoples vehicles if I am helping them or give those who ask advise to unhook their battery if they are welding on their own stuff. I don't want to be responsible for a blown ECU on some one else's baby, I would feel terrible.

Air gap on what switch? If there is high voltage on the +ve rail of any electronics then someone is doing welding on an actual electronic component or accidently burning through the wiring itself.

I weld with the ground clamp right next to whatever I am welding, either via MIG or TIG. I have never disconnect the ground on the battery as I feel it is safer to have it connected than have the entire car floating as opposed to having the chassis tied to a common ground.

 

[bfdiesel]

I was assuming the ignition switch. The air gap is what gives a switch its voltage rating. The switches I have looked at and some I have added on vehicles are 24 volt rated most welders use around 50 volts.

Smoking the electronics does not happen every time, but it can and does happen. Not a car, but I had to replace a FTE card and an electronic pressure transmitter last week after they welded on the piping next to it the FTE card is about 1.5 miles away from the transmitter and where they welded. The welders do not fry stuff all the time, but when the stars line up it happens and it is only when they don't let us know so it can be unhooked. A lifted lead anywhere in the line always prevents this.

Weld without unhooking the battery if you want, but I still won't say it is 100% of the time safe for your electronics.

"An once of prevention is worth a pound of cure"

 

[Conrad_Turbo]

The air gap would only come into play if you were inducing a voltage on the positive side though? I don't see how if you had a ground lead within 1' of where you are welding (say you are welding on the bumper) and how that would jump an arc in the ignition switch and fry electronics? I firmly believe having a ground connected to the battery will only help protect sensitive electronics.

 

[01tundra]

I will now cancell my email to Myth-Busters:sombrero:


You have done a lot of work/welding on your TUndra have you disconnected the battery in the past?

I didn't several times, and when I did it was usually because it was going to be in the shop for an extended period of time and I would just disconnect it to keep it from being drained (dome lights, etc.). The welding I did the other day was on my '03 Tacoma, and it was some substantial welding on the frame.

 

[Buliwyf]

Would make a good mythbusters show.

I agree that while it is unlikely, I can't discount the strories of some really sad technicians that blew up someones ECM.

 

[keezer37]

Well being the engineer that I am...

Can the EM field of the flow of current from welding fry electronics in the vicinity of the welding?

Can a degraded ground (built up resistance) of the welding machine induce a proportional voltage throughout the frame?

Can the confluence of a cheap, old welding machine and an older vehicle perhaps with poor shielding of the ECU conspire to fry the ECU?

I wonder about these items as I recently heard on Car Talk of a vehicle that shuts down whenever it is driven by an RF transmitter.