Welding Off Batteries. Trail Weld is a series battery welding system. I have welded on things while holding them and encountered no problems.
If you are an avid off roader DIY or prepared person this kit gives you the ability to arc weld easily and fits in a compact ammo can for safe storage. Disconnecting the battery does not assure EM damage and actually can help prevent it by presenting a load to the input of the battery powered and attached devices mostly the ECU when the car is off. It does work well in emergency situation.
If too little welding energy is applied the connection lacks mechanical stability.
I have welded on things while holding them and encountered no problems. A balance is important here. Elie Haddad research associate at Fraunhofer ILT says This is where the fast MikroPuls process can play out its advantages which can even be used to generate copper welds at. I have welded on things while holding them and encountered no problems.