Welders

[Zoobi]

One hard-to-kill totally false rumor about welding on vehicles is that the battery needs to be disconnected. Electrically speaking, there is no benefit to doing so. In fact, the battery isn't harmed by welding on a vehicle when it is connected and actually, having the battery in the circuit could theoretically filter (a battery also acts as a huge filter capacitor) out any spikes, though properly attaching the grounding clip close to the welding site makes any electrical spikes very unlikely. It truly is a false rumor the battery needs to be connected. That it does gets passed on like the gospel but it's of no benefit and simply isn't needed. Not to mention disco'ing the battery only disconnects the battery from the electrical system, everything else remains connected... like the far more sensitive components including the engine computer and alternator.

All this despite what someone's friend's cousin who is an "expert welder" said, since if you think about it, few welders know anything about electrical/electronic circuits beyond how to create a short circuit and melt metal.

Some interesting discussions on the subject

http://search.yahoo.com/r/_ylt=A0oGd...amage-cars-ECU

Yep, my buddy knows some one who used to.....See here, the factory says.....

The problem is the possible damage to the vehicle computers. Newer engine computers (pcm, ecm...) are very well protected, older ones were not. Body, gauge, air bag computers are easier to fry from voltage spikes.

Is it possible to "detonate" a battery while welding on a car? Absolutely but, you have a better chance detonating the batteries your using to weld with. Batteries produce hydrogen, add poor connections, high current draw and there you have it. When I use to use batteries for my Jeep welder I threw a floor mat on top of them. Any one who has witnessed a battery explode in a car will be cautious. My count is three, each one was while starting the engine (high current draw). 30 years in a shop, not too bad of odds there.

Back to the computer issues. Years ago I went away from battery welding and went to alternator welding. For me it was easier. If the ready welders were cheaper I would have one plugged into my alternator. On my 1980 Jeep I would weld on itself without any worry about spiking the distributor module or the radio. Remember the whole "electricity follows the path of least resistance" theory? Electricity has to go back to its source. Its much happier flowing between the electrode and clamp then say taking the longer harder way through that pesky engine controller. But the lawyers will ask "IS IT POSSIBLE" to burn out something? Sure, if you hook one end to the body, try to weld on the frame and the only path is through the electronics. People try to bring up voltage spikes like their something magical. They know how much damage can be done and that's where it stops. No one seems to remember that big voltage spike happening when their coil fires or the spike from the injectors...

I just say be aware of the potential problems, spikes can burn out computers and batteries can explode. The last thing anyone wants is being stranded covered with battery acid or not being able to start the vehicle because of a computer issue.


Scott

[HookandLadder]

Yep, my buddy knows some one who used to.....See here, the factory says.....

The problem is the possible damage to the vehicle computers. Newer engine computers (pcm, ecm...) are very well protected, older ones were not. Body, gauge, air bag computers are easier to fry from voltage spikes.

Is it possible to "detonate" a battery while welding on a car? Absolutely but, you have a better chance detonating the batteries your using to weld with. Batteries produce hydrogen, add poor connections, high current draw and there you have it. When I use to use batteries for my Jeep welder I threw a floor mat on top of them. Any one who has witnessed a battery explode in a car will be cautious. My count is three, each one was while starting the engine (high current draw). 30 years in a shop, not too bad of odds there.

Back to the computer issues. Years ago I went away from battery welding and went to alternator welding. For me it was easier. If the ready welders were cheaper I would have one plugged into my alternator. On my 1980 Jeep I would weld on itself without any worry about spiking the distributor module or the radio. Remember the whole "electricity follows the path of least resistance" theory? Electricity has to go back to its source. Its much happier flowing between the electrode and clamp then say taking the longer harder way through that pesky engine controller. But the lawyers will ask "IS IT POSSIBLE" to burn out something? Sure, if you hook one end to the body, try to weld on the frame and the only path is through the electronics. People try to bring up voltage spikes like their something magical. They know how much damage can be done and that's where it stops. No one seems to remember that big voltage spike happening when their coil fires or the spike from the injectors...

I just say be aware of the potential problems, spikes can burn out computers and batteries can explode. The last thing anyone wants is being stranded covered with battery acid or not being able to start the vehicle because of a computer issue.


Scott

Well put!

[mkjeepers]

More discussion on welding on a vehicle.

http://www.aws.org/cgi-bin/mwf/topic...?pid=27481;hl=

[mkjeepers]

I saw this on welding with 2 car batteries.

http://youtu.be/PV5oLPLUzrM

[Zoobi]

The first time I welded with two batteries and jumper cables, they melted through one of the battery posts. The cables were not as good as the ones in the video and we used a jumper cable between the batteries. The "kit" I put together later, mounted to the batteries. It worked so much better that way.