There is a method of soldering called ‘Resistance Soldering’ that is very popular among Model Railroaders. Basically it involves running a lot of Amps at a Low voltage through two contact points. The resistance between those points cause the area to heat up. THe contact point may consist of a contact ground clip and a carbon probe. It might also be two Stainless steel (or nichrome) probes. This method is sometime used for soldering surface mount components. The primary supplier of this equipment is American Beauty Tools
However their quality equipment is very expensive. There are also some DYI Resistance Soldering projects listed at various web site that involve modifying a available transformer (old Microwave, Battery charger, soldering gun, UPS). As I was looking at these I wondered if the same thing could be done digitally with a battery as supplying the power. My reason for a using a battery is that they can provide lots of AMPS for short durations and I happen to have several 18650 battery packs for ebikes. It would be convenient to be able to use them at a location where house current was available.I do not see why a 12 volt automobile battery could not do the same thing.
So I thought I would post the question here and let someone point out the gross ignorance of my idea … and hopefully explain why. The basic concept is to use an Arduino PWM output to limit the Voltage and Current going from the battery through a circuit with unknown resistance. The poorly drawn block diagram illustrates the concept. I have chosen 1-10 volts and 1-30 Amps as my limits. More amperage would require a shunt rather than Hall chip. It would also be getting too close to the 35 Amp limit of my Battery Management system.
I know that PWM can be used to control voltage but I have seen very little about using it to control Amperage. If I understand correctly there are two main parameters to the PWM control: frequency and duty cycle. I am wondering if one of these corresponds to current and the other to voltage.