(Possibly) dumb welding question...

I know you have to disconnect the battery to weld, but I've also seen disconnection of the alternator advocated...

Is this needed... Or even just prudent? I've fried a voltage regulator before, in the dim and distant past... But that was 'cos I was stoopid and forgot to disconnect even the battery! :doh:

i dont do either and havent had an issue though thats no guarrantee ,just make sure earth is good and near were your welding

It's always better to be safe than sorry and for the time it takes i always disconnected both to be on the safe side.
There is a one way diode in the alternator that can blow if high current is forced through it.

I just do the battery, even on new land rovers and never had a prob.

ive never dissconnected anything either....always get a good clean bare metal earth near where youre welding , it makes the welding better anyway. having got modern enough to have radio codes, id be wary of upsetting immobilisers by dissconnecting the battery but havnt had that issue myself. quite wtat happens when youve got puters and lectronics everywhere is anyones guess though.

I normally undo the battery +ve, and keep the earth close to the welding point, didn't have an issue in 8 hours straight welding ....

Mig is such low voltage(50v on a good set vs the kv spark pulses off a petrol engine) I dont really think its necessary if you have clean earths, but on electronic laden cars I do disconnect the negative just in case the old tail may be true

Tis true I have seen a P38 instrument pack buggerd and an alarm on a disco.

Wait so do you remove the negative or positive I'm just hijacking as I've got no clue and all the welding I've done has been off the vehicle or on the series I just took the battery out but on a disco the alarm will sound etc

Dr_evil said:

Wait so do you remove the negative or positive I'm just hijacking as I've got no clue and all the welding I've done has been off the vehicle or on the series I just took the battery out but on a disco the alarm will sound etc

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if you switch ignition on then remove earth clamp within 15 seconds alarm wont sound

Welding manual says to disconnect the battery and the alternator. Its up to you if you want to take a chance. I fried an alternator on a VW T25. I disconnect both terminals. Belt and braces approach for me.

ive heard people say so ,but never seen it myself in 30 years

Modern Mig welding shouldn't be a problem...

I've had trouble welding with Arc, but that was a long time ago and the wiring on the Triumph was shot anyways.

Dippypud said:

Modern Mig welding shouldn't be a problem...

I've had trouble welding with Arc, but that was a long time ago and the wiring on the Triumph was shot anyways.

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should have been using gas not burning holes with stick

jamesmartin said:

should have been using gas not burning holes with stick

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Evening James...

in them days I could only afford sticks...

rich peeps did Mig and Tig was fer NASA

oxy...don't go there...my Dad would freak

evening ,we were all trained on gas and stick, shouldnt think theres many do it now

jamesmartin said:

evening ,we were all trained on gas and stick, shouldnt think theres many do it now

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Only done stick and Mig...

Dad used to do oxy...then spent many years doing 'cut and drop', on many, many structure as the firms closed.

I always disconnect the battery

Just to be safe

FWIW disconnect battery negative as a minimum. On more modern vehicles I would advocate disconnecting ecu's as many are quite sensitive. Just made that mistake on my RRC, although battery disconnected EFI ecu has developed a fault - could be a coincidence but I suspect with the amount of welding I have done I have fried the ecu. Good job I have a spare!

when doing the back end i dont disconnect anything but when doing the inner wings i whipped off the neg battery connection just to be sure and i have spend many an hour mig-ging the disco now and no obvious problems so far.