I am a novice in electronics. Doing it as a hobby. In one of my projects, I am facing an issue whereby I see arcing whenever I connect my 12V lead acid battery to my circuit. The reason I say this is because I can see a brief flash of 'spark' at the point of contact and alittle bit of sound at that instant. Then one of my sensors (INA219) will blow (specifically the R100 resistor of the INA219) and I can see smoke arising from it. My thoughts are that the circuit is suddenly drawing too much current in that instant when I physically connect the wires causing a spike in current. This does not happen when I use my power supply from my wall socket which passes through a fixed 12V 5A DC regulator. As I am not an expert on this, and might be incorrect in my judgement, I would thus like to ask for advice on this. I am thinking of using a resistor at the point of the connection between the wire from the battery and the wire from the circuit, to prevent this 'spike' in current. What kind of resistor should I be looking at (if a resistor should be used at all)? I trialled with a 1.5 and 4.7Ohms, but that doesnt seem to provide enough power to the components in my circuit. Ideally, I would like a resistor that can allow 5A of current to pass from my 12v lead acid battery. Otherwise, what other ways can I do try to minimise this arcing?
closed as unclear what you're asking by Olin Lathrop, Michel Keijzers, Finbarr, laptop2d, Dmitry Grigoryev Apr 17 '18 at 9:10
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Difficult to judge without knowing the circuit. I'd suggest you add one.
A 12v lead acid battery (if one from a car) can provide a lot of current. You might be having problems with inrush current, which is mostsly a current peak needed to charge all the capacitance in your circuit. Do you have a lot of capacitance?
A common strategy to prevent this is using an NTC (negative temperature coefficient), which will have a high resistance initially and then drop as you have some current running.
Take a look at: http://www.mouser.com/ds/2/168/920-325D-LR-245176.pdf
The problem is with your circuit, not your power source. The circuit evidently has a problem in that it can't handle the power input rising quickly, and then be able to deliver essentially infinite current. Fix that.
The difference between the car battery and the power supply is that the car battery doesn't have current limiting. It can supply a few 100 A. The power supply probably has a capacitor on its output, but other than that can't supply more than some maximum current.
Your circuit apparently draws way more current than it should when first turned on. This may be due to something like a FET gate that floats when power is first applied. Without a schematic, there is little more to say.