Welding and batteries

[Gaston aires]

I need some welding done to my scooter rack which is fixed to the van chassis.
Would it be advisable to disconnect the earth from the engine battery and hab battery before welding? Fiat Ducato chassis.
The job is being done Saturday.
Phil

 

[ChrisL]

Yes, at least that's what I was taught in welding school and what I've always done, however I've never seen the consequences of leaving them connected and something going wrong, if there were any earthing issues with the welding circuit it may cause issues with electronics in the van, maybe someone else has first hand knowledge of damage caused by welding whilst the battery earths are still connected.

 

[Conal]

Just watched ”woo woo 883” on YouTube welding a Morris Minor exhaust. He has two cables (one positive, one negative) with a device between than that he says, when attached to the vehicle battery, prevents damage. Others here will probably be better informed.

 

[Odd-no-more]

Way back when I was a car mechanic I saw an alternator's dioeds wrecked by welding with the battery connected.

 

[L' Hobo]

Yes, at least that's what I was taught in welding school and what I've always done, however I've never seen the consequences of leaving them connected and something going wrong, if there were any earthing issues with the welding circuit it may cause issues with electronics in the van, maybe someone else has first hand knowledge of damage caused by welding whilst the battery earths are still connected.

I too was told this on a negative earthed vehicle (there was still a few Positive earthed vehicles around when I was told this ) before doing any welding.
These days, I disconnect the negative connections on the leisure batteries too but I've never seen the outcome if I didn't?
Bugger a few fuses and electronics at the very least, I would imagine?

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[Gaston aires]

I think disconnecting is best. Easy on cranking battery, not as easy on hab battery. Probably for the best.
Phil

 

[tonyidle]

As long as the welding earth is connected to the scooter rack there's no need to disconnect anything.

 

[Landy Andy]

These days there is a special box that provides safety whilst welding. It’s connected to both battery terminals.
Im sure the people doing the welding will know.

 

[L' Hobo]

These days there is a special box that provides safety whilst welding. It’s connected to both battery terminals.
Im sure the people doing the welding will know.

I'm equally sure there is a lot of us who only do welding occasionally these days, that did not know about this, could you explain further please?

 

[Stoosal]

I play safe and disconnect battery and alternator. Never sure with a motorhome what else may be affected as so much more is connected.

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[gus-lopez]

You need to disconnect the starter battery,hab battery & the feed from saolr to the regulator. leaving connected will short loads of stuff & has a good chance of frying the ECU. Most welding firm s working on vehicles by pass this by using a shunt .


You need to panels disconnected,if you have any, other wise you will have live cables even disconnected from battery

with a device between than that he says, when attached to the vehicle battery, prevents damage.

Called a shunt yeras ago

Bugger a few fuses and electronics at the very least,

Not good if the ecu ,bcm etc go 2 or 3k's worth to replace.

I'm equally sure there is a lot of us who only do welding occasionally these days, that did not know about this, could you explain further please?

I've ever only known them called a 'shunt' .no idea what the proper term is?

 

[steve69]

If in any doubt........just disconnect.

 

[dazandandrea]

Ive always Disconnected batteries and unplugged ECUs just to be on the safe side .
In my view far easier to spend 10 minutes unplugging/ disconnecting things than spending hours and possibly lots of dosh on replacing things.

 

[TheTwoOfUs]

Just a thought Phil but would it be easier and safer to unbolt the rack and be certain no damage will be done when welding.

 

[dazandandrea]

Just a thought Phil but would it be easier and safer to unbolt the rack and be certain no damage will be done when welding.

Definitely the safest way to do it.

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[RogerIvy]

We’ve always disconnected to be safe.
However, we needed to weld something on a vehicle a year or so ago and I researched current best practise. It was quite conflicting. Something to do with modern electronics. Some swear you have to disconnect and other swear you must not disconnect otherwise things go wrong. Go figure. We did both actually, nothing blew.

 

[jockaneezer]

A slight diversion, but I watch a few YouTube videos of truck/machinery repairs being carried out in small workshops in Pakistan. They seem to break a lot of drive shafts and differentials, but have no qualms about welding them back together ?
What upsets me is, they will electric arc weld an item that's being held in a lathe, (sometimes they cover the machine bed, more often they don't) but the welding "earth" is often just a length of rebar resting on some metal part of the lathe's bed, with the high amperage welding current travelling through the lathe's headstock bearings (one of the main sources of accuracy on a lathe)
I need to do an experiment at home next time I find a large, undamaged bearing on my scrounging searches and try and see just how much damage/pitting is caused by passing welding current through the contact points of the balls/raceways ?
ps. I personally would disconnect the batteries of your van.

 

[Gaston aires]

Just a thought Phil but would it be easier and safer to unbolt the rack and be certain no damage will be done when welding.

Sadly no. The whole point of the welding in situ is to make the rack easy to take off.
Phil

 

[chatteris]

have seen a lot of welding done on vehicles with nothing disconnected,never known it to cause a problem.
it used to be said you needed a device to absorb voltage spikes and i have one and used it in the past but think as long as you have earth close to area you are welding and are away from ecu etc you should be ok