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Mig Welding modern cars
macc man - 20/11/20 at 12:04 PM

This may have been covered before, but I just wanted to pass on a recommendation for a protection device when welding on cars.
Previously I always disconnected as much as possible battery ecu alternator etc before welding. I damaged an old cavalier once when welding the exhaust. I recently did extensive welding on my Transit Connect. I connected a Sealey Prosafe 12v protector across the battery terminals disconnected nothing and was pleased to report no damage to anything. This could save thousands in damaged electronics. It cost £62 from Ebay and was well worth the investment.

tegwin - 20/11/20 at 10:52 PM

The question is.... would there have been no damage if you had not have used the expensive device?

Mr Whippy - 20/11/20 at 11:02 PM

Personally I'd disconnect the battery and pull out the alternator plug just to be safe. Mind too that modern cars, vans etc use adhesives extensively, plus high strength steels both of which can be badly compromised by welding. Repairs to body shells has become much harder if not impossible to do safely without specialist gear and detailed repair guides.

For me to prevent frying wiring, just connect the earth right next to the part or area your welding not clamped onto some remote part of the car. Electricity takes the shortest path of least resistance.

[Edited on 20/11/20 by Mr Whippy]

coyoteboy - 21/11/20 at 03:08 AM

Return clamp right next to weld, leave the battery fully connected (it smoothes any spikes).

nick205 - 22/11/20 at 04:45 PM

What do we define as modern?

Anything with an ECU and fuel injection?

Year 2000 onwards?

JAG - 23/11/20 at 08:14 AM

quote:

What do we define as modern?

Anything with an ECU and fuel injection?

Year 2000 onwards?


My engine is from a 1994 MX5 and that has an ECU and fuel injection

cliftyhanger - 23/11/20 at 12:38 PM

I have been using a surge protector for years. Just an extra piece of insurance against zapping something expensive. Cost me £15 back then.
And yes, leaving the battery connected is a good idea, as said it softens any spikes.

nick205 - 23/11/20 at 02:48 PM

quote:
Originally posted by JAG
quote:

What do we define as modern?

Anything with an ECU and fuel injection?

Year 2000 onwards?


My engine is from a 1994 MX5 and that has an ECU and fuel injection



Cars had ECUs and injection earlier than 1994, I've had several Peugeot 205 GTIs with UCEs and injection from the mid to late 1980's.

My question was general really as in does the OP have a year after which he considers cars to be modern.

coyoteboy - 23/11/20 at 07:32 PM

Doesn't really matter, the same best practice applies to all, you're just safer on older cars as they tend to be more tolerant, I think.