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What to disconnect when welding?


reb78

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I can never find a definitive answer on this question. What should I disconnect when welding the body shell on the D2 (if anything)? I have put this here rather than the disco forum as it would be the same question/answer for a lot of different models.

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Always the battery and always place the welding machine earth as close to the place your going to weld as possible , a polish guy burnt the wiring out on a machine because he earthed at the bottom when he was welding at the top when I worked maintenance . Might also be wise to disconnect anything with a memory .

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Honestly, never disconnect the battery.

Reason is, the battery acts as a lovely sink for all the horrible current spikes that may end up in the system.

Without the battery, there is more chance of the spikes going somewhere else, and doing harm.

Above advice about keeping the earth near the workpiece is entirely valid, will certainly help.

The only time I have ever damaged anything by welding on a car was when I was welding up an alternator bracket, with the alternator still attached (I wanted it for alignment purposes....).

 

 

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I'm with Bowie, i never disconnect and never had a problem.

The danger will be currents conducted in the ground wires, if the resistance of the wire is less that the resistance of the welding current path through the body. Or voltage spikes induced, but thats less likely in normally well protected car systems.
Put the ground next to the weld and have in mind what you are welding close to.

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On 10/11/2020 at 7:41 PM, Bowie69 said:

Honestly, never disconnect the battery.

I agree too.  So long as the earth is as close to where you are welding as possible, the chances of a current of sufficient magnitude to damage anything gettin close to anything that could be damaged is rather remote.

My feeling is the advice is in order to protect from the hard-of-thinking - TIG Welding with HF Start and the earth attached to the ECU would probably do it!

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My welding instructor always said that there was no need to disconnect the battery if you had the earth close to the site you were welding. So I've stuck by that. My mate who is a welder by profession says the same. I've never disconnected the batteries on the Disco, no matter what is being welded. They are only just starting to go downhill now, after 6 years of being on the vehicle...

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On 10/12/2020 at 1:01 PM, zardos said:

You can also buy Surge protectors like https://www.weldingdirect.co.uk/12V-Battery-Surge-Protector

So you don't need to disconnect anything.

Does anybody have an idea what's inside that box? I assume coil/capacitator, to limit current spikes? Not sure how effective that would be when wired in parallel.

We have the habit of disconnecting the battery negative when welding. If we don't forget... Reading this makes me wonder if we should bother. It's not much work, and wont have any consequences on most vehicles we see, except for the radio settings and the windows on a P38. But if not necessary, might as well leave it connected.

Filip

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Well. Opinion went 50:50 In this thread when I was about half way through the job. I disconnected all  ECUs and the battery. My hands are too big to easily get to the alternator on a TD5 so that remained connected. Earth is always near the work area. Its all gone back together and started fine. 

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