Should you disconnect the battery before welding?

I did a serch for this to no avail. If I'm welding on a car should I disconnect the battery first or any other electrical items before welding. For what it is worth the car has a generator. Not an alternator.
Todd

 

I always do. nothing to back it up, just a practice ive always had working on heavy indutrial equipment for 20+ years..Might help the electrical devices. Battery too.

 

dont know if it can cause damage, but may as well disconnect...better safe than sorry, and it only takes a couple seconds right?

 

not to mention if it has a computer or any systems like that

 

Yes

 

If your car has a ECM you're suppose to, but it kind of seems like a good idea regardless.

 

Yes. You don't want different potentials floating around. That can tend to do odd things.

 

Yes, that's how I cooked a battery terminal on a 29 roadster.

 

What are you welding? The frame? body panels? exhaust? I've welded exhaust systems for over 25 years on cars on a daily basis with and without computers and never disconnected the battery once. There was a big scare when computers first came out that never materialized. Yes I predate computers!. If it's got a generator it's very welder friendly. If you hang the ground clamp on the front bumper and weld on the rear quarter panel, the amperage can go places it shouldn't go getting from point A to point B. Put the ground clamp as close as possible to the weld. Electricity takes the path of least resistance. It's not going to run all over the car if there is a direct path provided. Put the ground on the piece that you are welding. You'll get better welds that way anyway.

 

yes. dont forget to take out your msd too.

 

If you put the negative on the positive and the positive on the negative it will charge your battery.

 

Not to be negative, but are you positive this works?

 

Keep the ground clamp as close to the weld as you can. The current will do damage. If you are welding on the exhaust don't ground on the body. If your welding on the door ground the door. Dont let the current bass through the hinges or it could ground through any door wiring.

 

Tim, you could live in Texas with that sense of humor.....The muffler guy that put the system on the 5w said that was a crock. It ran fine after he finished.

 

Listen to Tommy. I'm an old guy ,too and done a lot of welding on all kinds of vehicles, never lost any electrical componant as a result. By doing what he suggests.

But don't use the CD player while spray painting, the overspray sticks to the discs. Very hard to clean.

Frank

 

On modern vehicles you unhook the ground on the battery, and ground as close as possible to your weld. I have never, (knock on wood) run into a problem doing so, and i do alot of welding.

 

Do it, I've got a brand new MSD box that doesn't work and I'm pretty sure it's because I did some welding on the chassis without disconnecting it. I don't know for sure that it wasn't junk right out of the box but, heck it says in the instructions to disconnect it when welding, I didn't, it doesn't work. 2+2=4.

 

good tip here,go to walmart, for under 5 bucks, you can get a disconnect that is for a trolling motor battery, it has a clamp that clamps to the battery post,then the battery terminal clamps to the side of it. it had a bolt in it with a big plastic thing you unscrew. the bolt carries the current when it's screwed in. unscrew it and your ground is positivly disconnected. takes about 3 seconds to do so. i have one on every car i own. it's also a safety feature,if you ever think you have an electrical fire, pop the hood and in three seconds the battery is disconnected.

 

You should pull the ground on you battery any time you work on your car.

I turned a 9/16 wrench & a battery cable into a Welding Torch while changing header gaskets once...!

 

yes...pull the ground cable just to be safe.
even if the car doesn't have an ecm or anything like that.
where i work, it is mandatory that the batt. ground cables are removed before ANY welding is done just to be on the safe side.
a semi truck ecm is about $1800.00, and it's better to be on the safe side. i have seen ecms, alternators, batteries, radios and other electrical stuff burned up because the ground cables were not removed. maybe those were just flukes, but it does happen.
it only takes 30 seconds to pull the ground cable....why mess around, just pull it.

 

I had it happen to me last summer, a friend hooked the ground of the welder right to the stud my battery was grounded to. I lost a headlight (melted the soldering right off), points, cooked the oil out of the coil and drained the battery dead. This was a stick welder while welding on the frame.

 

this is what i was talking about,and they are cheap and work great.

 

I must be very, very lucky!
After reading all of the posts so far I don't know how I didn't ruin my jeep. I had a rather large power inverter installed on it and had my 100A 110V Lincoln welder plugged in. If we would break off road I would run my jeep and weld for long, long periods of time. I did this for about 11 years without one computer, sensor or any other failure.

Why did this work for me and doesn't work for anyone else?


BloodyKnuckles

 

yes!

 

i just picked one of these up the other day. the "cheap" thing that i didn't like about it is the way the want you to mount it. you mount the quick disconnect terminal to the battery, and then your old batt cable terminal is connected to the quick disconnect end....so you end up having 2 batt. cable terminals hooked together. (that looked really cheesy to me when i saw that on the back of the package) i took the quick disconnect terminal apart because there is plastic insulating the 2 peices. this conector is 2 peices. if you unscrew the "knob" all the way, you can slide the 2 peices apart. (look at the pic...the white stuff in the terminal is plastic). i ground down the end that you're supposed to hook your old batt. terminal to, just enough to fit it into a metal sleeve (used for splicing batt cable together). then, i soldered a new battery cable into the sleeve, and put heat shrink over the connection. this way, i only have one battery terminal on the neg side, rather than the hokey way they want you to use 2 battery terminals. this works great...all you have to do is turn the green knob about 2 turns, and your battery is disconnected.

 

My buddy was welding on the frame of his 51 Chevy. It had three battery's for the hydros. Well long story short the top blew off of one of the batteries and sprayed acid everywhere.
I'd say disconnect it.

 

...all very interesting, but by the time it took to type this question you could have just unhooked your battery cable!

 

With the opportunity for dampness/moisture, or poor insulation, or intermittent "shorts" between adjacent crimp terminal connectors, all able to conduct in paths not expected, means that I'd best remember to disconnect. If you've ever tried to deal w/a poor "ground" situation, the current paths are a real challenge and apt to go almost anywhere. So, the ECU thing does matter (newer cars) because voltage spikes can upset the (fine print) circuits. Thanks for the reminders!

 

hmm the one i got at walmart seemed to be a little bit better then that one in the pic,, i will take a pic when i can.

 

have welded on both, it is a coice of the person doing the job

i have and havnt, been doing this practice for 20+ years and have not had any issues