streaky Posted April 22, 2008 Share Posted April 22, 2008 Following on from the other thread about disconnecting the battery during charging. Why is it advisable to disconnect the battery prior to doing any welding on a car? I also heard that disconecting the alternator is advised. Anyone care to elaborate on this as well please? Would it make any difference depending on the type of welding..ie, Arc welding, mig, TIG etc? Thx. S. Quote Link to comment Share on other sites More sharing options...
steve_d Posted April 22, 2008 Share Posted April 22, 2008 I will also wait for a grownups reply on this as I was advised to disconnect the alternator but the battery was not mentioned. Steve Quote Link to comment Share on other sites More sharing options...
carl hurst Posted April 22, 2008 Share Posted April 22, 2008 The diodes in the alternator are very sensitive and will blow if you send welding current through them so disconnect and this wont happen,Or so i was told, Carl. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted April 22, 2008 Share Posted April 22, 2008 I've always been instructed to disconnect both the alternator and the battery doring any electrical type welding. The alternator because odf the diodes. The battery because of any spikes[ for wont of a better word] mike Quote Link to comment Share on other sites More sharing options...
D9OSV Posted April 22, 2008 Share Posted April 22, 2008 Also be aware that TD5 alarm units (10as) do not like spikes caused by welding even with the battery disconnected. On more than one occasion we have had to replace units that have been damaged due to welding on the vehicle or at the very least have had to relearn the security settings. So be careful Jim Quote Link to comment Share on other sites More sharing options...
Steve Hiatt Posted April 22, 2008 Share Posted April 22, 2008 When I was at Ag Eng college my electronics lecturer maintained you were more likely to damage the alternator by forgeting to reconect it than by the welding itself. Quote Link to comment Share on other sites More sharing options...
bobtail4x4 Posted April 22, 2008 Share Posted April 22, 2008 When Ully welded the diffpan on my Rangie, the spike made the ABS ECU go into "I give up " mode. only fixed with a new ecu. Quote Link to comment Share on other sites More sharing options...
Mark Posted April 22, 2008 Share Posted April 22, 2008 Whilst I believe it is good practice to disconnect alternators, batteries and ECU's when welding - I always do - Dynamo's are fine I discovered this weekend.... hope that helps.. Mark Quote Link to comment Share on other sites More sharing options...
Astro_Al Posted April 22, 2008 Share Posted April 22, 2008 Would it make any difference depending on the type of welding..ie, Arc welding, mig, TIG etc? You might have to be more careful with Tig if it has a high frequency start (or continuous) mode. I can't imagine anyone would be tigging part of a land rover in AC mode, so that shouldn't be an issue (unless you're fixing a body panel with it still attached - unlikely). Al. Quote Link to comment Share on other sites More sharing options...
Mark Posted April 22, 2008 Share Posted April 22, 2008 gas welding is fine too - no need to disconnect anything when using gas.... I am full of helpful comments tonight... Mark Quote Link to comment Share on other sites More sharing options...
disco tony Posted April 22, 2008 Share Posted April 22, 2008 I once heard of somebody knackering a gearbox because of a poor earth clamp, placed at the opposite end of the vehicle to where the welding was being done the current managed to arc between two gears. Dont know if this is true but came from a Cranfield diploma qualified welding engineer, IE, a reliable source. As the gearbox is always earthed, disconnecting the -ve should eliminate this problem. Quote Link to comment Share on other sites More sharing options...
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