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How to isolate a battery pack from a controlled short? Answered

so i am trying to make a portable electric stove and am trying to isolate the heat coil from the battery pack itself i know there is a way of doing this however for the life of me i cant remember how it works or what it is called. any help would be greatly appreciated!

[edit] so there was some confusion on what i am trying to accomplish. i keep burning up batteries (when i say burning up i pretty much mean just that.) they don't like being connected to circuit that's sole purpose is to short out (albeit in a controlled way.) i wanted to isolate the batteries from the part of the circuit that is shorting to create the heat. if that still doesn't make sense or you think my problem might be something else entirely, please let me know.

also so you know what my circuit looks like. it is a battery box power supply soldered to my heat element as well as a variable resistor to allow me to change heat output.
hopefully that helps clarify.


It sounds like you are using the batteries to power the heater, but drawing too much current and damaging the batteries. You mentioned a variable resistor, but even if it could handle enough power to control the heater, it would waste power and heat up as much as your heating element (at some settings). I think you want a PWM controller, like the ones that are used for DC motor control, to provide power to your heating element without wasting it all in the process.

... and note that if you cut down the power being drawn from the batteries (so they don't overheat), you will also be reducing the power to your heating wire (so it may not heat up enough). Finding a combination of heating-element material and power supply that works may take some experimentation... or going back and doing the math to figure out how much power is actually needed and determine how large a battery pack you'll need.

Based on your updated query, I'd suggest that you look into constant current sources. You can either use PWM as a method for controlling the current delivered to your elements or a linear controller (ex: lm317, although that by itself would most likely be insufficient to the task without a secondary fet/bipolar/etc. to control large currents) ---------------------------------------------------------------------------------------------------------------it seems someone forgot that many of us don't like to produce single paragraph responses and failed to provide proper coding for linebreaks without pissing around with the rich text editor --------------------------------------------------------------------------------------------------------------- PWM, or pulse width modulation, can be used to control the effective DC current input to your elements with considerable precision, by adjusting the pulse width and frequency of the control signal. With proper feedback, it can even be controlled by a set temperature!

An electromechanical or semiconductor relay will isolate the battery side from the stove, but only if you intend to power the stove from a separate supply. If you mean a circuit interrupter, like those used to protect batteries in a solar charging situation, then too a relay can be used. As Redesign said, it would help if we knew what you intended to do.

It sounds like you're thinking of an optoisolator or an isolation transformer, neither of which would do anything useful for you electric stove... so I agree that you need to provide a better explanation of what you are trying to accomplish.

A switch? It not then I'm not sure what you're trying to do.