anti-spike device for cars

Hello All

I am new to this site and this is my first post so let me introduce myself first, my name is Andy and I am a self employed mobile welder.

I think this is a great site with some very helpful topics.

Anyway, I am looking to find an anti-spike device for a car. I have noticed the following site saying that disconnecting the battery makes no difference.

http://www.difflock.com/buyersguide/tools/welding3.shtml.

Any help on this matter and where I would find a good deal on such an item

Many Thanks

Andy

That info is just a plug to sell their spike devices.

Disconnecting the battery will make things worse. If you do disconnect the battery, connect the leads together.

That stuff about stopping the arc is crap. The arc stops 100/120 times a second unless you have a 3 phase MIG.

Adding s spike suppressor will make no difference. If there are large magnetic fields it will zap the compute via the numerous wires sensor inputs and outputs connected to the computer. The power leads already have spike suppression as there are already devices that create larger spikes (turning of the A/C is one.) Not to mention 300A of starter current that creates a huge spike when it is turned off.

Power in cars typically has 150V spikes. This goes back since day one of cars. I remember dealing with cheap radios that could not handle the huge spike the clock generated once every 10 minutes (had solenoid winder.) Moder cars systems all have suppression in their electronics. Semicondictor companies have entire families of parts just for the noisy power in cars.

Best just to use sense when welding. Welding an exhaust and grounding to the frame would be bad. The O2 sensor is sitting right in the middle of the exhaust. As the exaust is only grounded through the engine flange and that has rusty bolts, the O2 sensor wires will make a return path through the computer.

Connect the ground close and to the same system your are welding. When welding a frame, those nice big flanges on the tranny, may be convenient, but again you are running a huge current through the ground lead on the engine (the entire drive train is shock mounted so usually only one wire as a ground.) It is a DC ground, the HF currents of welding will cause the engine to have considerable voltages above ground. The computer is grounded to the frame so now all the sensor inputs to the engine have welding induced voltages.

As a factory authorized electronic repair for GM, Ford and Crapler, I read all the tech bulletins (mosty from GM). The only one on welding said connect the ground close to the work and on the same system (frame, exhaust, engine, axle.)

Wow Thanks Shenion, You certainly know your stuff.

I will certainly remember your comments when i have welding repairs on a car, What a relief I can keep the battery connected without losing memory on the radio etc.

It is very strange how every mechanic or diy welder that I know will disconnect the negative lead.

when I saw "Anti Spike" I thought you were going to talk about these:
http://www.ebaumsworld.com/video/watch/26144/

Thats a good find greyshirtguy. Think i will get a set of these tyres and put them to the test, against the local police force....lol

Something similar to the run flat tyres you can get.

Thats great info about not having to disconnect the battery on a vehicle when welding, I always have since someone told me to (with no explanation), now I know its a myth that welding while connected can blow stuff up. cheers.

I was always told to disconnect the battery too, I was led to believe it was to protect the diodes in the alternator (I'm going back a few years mind, most cars I used to weld had points and carburettors )

Wozzaaah said:

I was always told to disconnect the battery too, I was led to believe it was to protect the diodes in the alternator (I'm going back a few years mind, most cars I used to weld had points and carburettors )

Click to expand...

The only one i welded had a carb and points
Fiesta, Xflow engine, nicknamed the 'XR1 and a bit'
1100 engine, xr2 interior and body kit.... capri pepperpot rims, that were about 30+mm too wide to fit under the arches

As for the diodes, thats what i was told aswell.

Never bother anymore. Even on brand new trucks and stuff, never had any problems.

My Father in law still disconnects the battery and he has been in the welding trade for over 20 years, I can probably guarantee that most professional or DIY Mechanics/Welders in this forum will remove the battery.

It cant do any harm if you do.


Build quite a few lorry boddies for another comapny who build special vehicles they hardly ever bother either.

Has anyone actually blown alternator diodes? Still curious about this, even though I am a reformed battery remover.

I have never done any damage, but it’s a pain when you reconnect the battery after finishing and you have no music (dam... where is my radio code)

How about a simple memory saver Andy?
Plug into lighter socket, run from an integral 9v battery.

That’s a good price. Better than calling out someone to reprogram everything.

At my previous job we had several ECU's on various makes of lorry ******** by people NOT disconnecting the battery before welding. The advice from the manufacturers was to remove a battery lead, others said to remove both and bolt together.

No comment to make about ECU's but I have spent many hours welding using a forklift as a prop or a bench when building large fab jobs, sometimes with the engine running sometimes not, and haven't fried an alternator yet,