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Graham Watson
New User
Username: graham508

Post Number: 7
Registered: 3-2016
Posted on Friday, 08 April, 2016 - 22:44:   Edit PostDelete PostView Post/Check IP

Hi all,
I have some floor repair work to do on my MKVI and will be using a MIG welder. Other than disconnecting the battery are there any special precautions I need to take due to the car's electrical system being positive ground?
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ross kowalski
Experienced User
Username: cdfpw

Post Number: 38
Registered: 11-2015
Posted on Tuesday, 26 July, 2016 - 13:45:   Edit PostDelete PostView Post/Check IP

No special precautions.

I once welded a battery tray on an old motorcycle (well not that old, but positive ground) and managed to accidentally repolarize the dynamo.

I noticed my custom LED taillight was out, but it tested correctly on the bench. Hmmmm. A little battery arcing later all was well.

Seriously, if the battery is unhooked, and you are not running any modern electrical additions, and you ground well and close to the area being welded you will be fine.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1057
Registered: 5-2015
Posted on Wednesday, 27 July, 2016 - 06:04:   Edit PostDelete PostView Post/Check IP

Once the battery is removed the will be no problems. And if the has a dynamo then the battery can be left connected but take it off any way in case you short something out will grinding and cutting stuff around. The reason for disconnection comes from alternators and electronics which CAN be damaged by heavy eddy currents in the cars body work. Dynamo cars have no electronics and would be un effected by eddy currents.

Note the diodes in air con equipped cars. These may blow out if subjected to eddy currents/voltages.

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