I make it a rule to never weld on a car with complicated computers like the rangies. Only if its an absolute must, I will disconnect every computer I can get my hands on but by that time, you may as well remove whatever it is you are welding. Being an exhaust, its easy.

I have worked on larger earthmoving gear where despite the batteries being disconnected, welders have fried $60k worth of computers in a minute.

I would prefer to not take the risk of welding current frying the electronics by using the double earthlead close to weld method for difficult to remove parts but on easy parts just take it off.

We had an issue with an automatic welding machine (offshore pipeline welding) that fried it's own control eletronics because a little weld spatter (the parameters weren't set perfectly yet and we used a CO2 root weld) landing on the torch and torch holder, bridging the insulating sleeve. The current went straight through our computer and before we realized it was the weld spat blob thingy we fried two PCBs worth about 250 USD each .

We used a different sleeve / torch / arm pretty soon as well after that (and order plenty spare PCBs just to be sure).

As for welding wire and gas, if the stainless wire holds great, if not you can still get carbon steel wire.

Unfortunately I don't have access to gas/oxy welding equipment as well as my dads magic hands (as in he is still alive and kicking just living a 12 hour plane ride from here) in case I would have to do welding on an exhaust or structural member. He did magic for me on my old Triumph Herald that I bought as a poor student. Hole in the muffler, he would patch is up, no problem, big patches as well, amazing to see such skill. Save me tons of money (and him as well for his own cars).

Luckily I do have my hobby MIG and CO2 cylinder here so I can still finish my trike (well first finish this 3 month paying job ).

Sorry got a bit off track  MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Disconnect as Craig says, or use one of these or similar

http://www.ebay.co.uk/itm/Power-TEC91144-A...4640842209

OOOooooo I forgot about those clip on anti zap protection things, when they first appeared on the market they were such a stupid price it was cheaper to fry the ECU's But that is a good price, the only question is do they work? I'll have a dig around I thinks  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

yes they do - of course disconnecting the battery is cheaper!

Haylands wrote:

Never had any bother frying ECU's either, without fancy earth straps and never waited for longer than 5mins after disconnecting battery (didn't know you should Craig )... also have to admit to not bothering on several occasions and not had any bother... maybe I've just been lucky though...

Pete, its simply belt & braces pal... If you do a soft battery reset, you wait for the ECU’s to power down, loose their residual power, kept in capacitors etc etc... Not everyone would understand a hard battery reset! But would negate the need to wait

miggit wrote:

The hours wait is lunch time He didn't think to start earlier I would have thought that once the battery was disconnected everything was pretty much isolated, especially if you keep the weld area to a minimum ie, don't earth at the front bumper and start welding the rear

FYI Argon / 5% Co2 mix is the best thing for steel, not pure Argon, which is normally used with a TIG on stainless and ally. I did try an Argon / Co2 / Oxygen mix once, worked well with surface rust, but I'd recommend a good wire brush and get the cheaper stuff

Miggit, as i said to Pete above, its a belt & braces thing pal...

And when you do an ECU scan and realise there are between 20 & 35 ECU’s in all FF's Could be a VERY costly mistake

Craig, bud, I understand the belt and braces bit, at the end of the day you is playing with someone elses' ffrr and as a business you have to look after the companies interests, wouldn't want to be explaining why an ECU has stopped working Have you any experience of those de-couplers ?

And I suppose that it's wise to err on the side of caution, lets face it a ffrr doesn't need much of an excuse to bit you in the bum  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Cheers Craig...

Miggit, it was 5% something else gas, not neat Argon

It's always the way though... I mean to disconnect the battery,
just keep forgetting, I've been lucky up to now... Pete
I now have permission from the boss to use Y.O.L.O. Enjoy life
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Pete, for mild steel you should use 5% Co2 95% Argon for metal up to 5mm thick and it used to be 10% and 15 % Co2 for thicker, but I think that they now only have 1 (BOC) they call them Argoshield light (5%) and Heavy , In fact scrub that I've just had a peek and they now do light up to 4 mm, Universal 4 to 10 mm, and heavy 10mm +.
Most people that do welding gas, do a Argon Co2 mix, 5% to 7.5% Co2 is what you need for de tin stuf

1-2% Oxygen in the mix is fine, but I wouldn't pay extra for it. In fact I'm not too sure if they still add Oxygen in to the mix, it was supposed to increase the weld temp and help with slightly oxidised material, I found that it was good on paint  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Pete there's no need to remove the battery connections when your welding your bumper on the bench
If you've been welding on the car Luck must be your middle name  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Well I've just had an interesting 10 minutes going through Rave in the Body Repair section, and while it does say to disconnect the negative lead from the battery it does not recommend disconnecting any ECU's, but it does recommenced that the alternator is disconnected in most operations, and waiting 2 minutes before starting

I've also been looking in to the Anti Zap thingy, to see if they do / don't work, from what I can make out they do work, and they seem to be a favorite with the exhaust fabricators, all be it the Snap On one, with the Snap On price tag

I'm now wondering if there is any mileage in disconnecting the battery and fitting one of those anti zappers, or do they require 12 v to work? Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

I'm happy to be corrected by someone more qualified however my understanding is that they act as a surge protector so monitor the voltage for any spikes and cut to a safe level if necessary, so logically the battery would need to be connected.

Miggit... Oh I see, I thought if I welded anything that has been anywhere near the fatty I best disconnect the battery....

I actually welded these on with it connected.... oooops



Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated  Pete
I now have permission from the boss to use Y.O.L.O. Enjoy life
__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand Sold
2002 L322 Vogue 4.4 V8 Epson Green (Fatty Offroader) Sold
-Click for Project Fatty off roader-

You Live Close to the Edge, Pete

And welding precautions, not only should you disconnect the battery if you are welding with in 50 feet of the car, I recon that you should drain the tank and have a Fire Engine on standby One can never be too careful Land Rover was a part of British Leyland Enough said  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!