JMD1: Can somebody pls suggest me a circuit that covers the following requirements: Something that makes a 9V battery pull 5A for 5s when activated by arduino ( i have relay module). So how can I pull 5A out of 9V battery? It is for heating NiCr wire, 5s are enough.
I was thinking of a similar question. I know that a typical Alkaline 9V is good for 500mAh, and Lithium in the 1000mAh range.
I've got some Arduino Geocaches that I'm building, and I need to open a latch that will draw about 0.9A at 9V, but I'll be doing it for no more than 1s at a time. I was trying to figure out if it would deliver it, for that short of time, given a 100mA and 5min run time between resets (8.33mAh consumed per run), that's at least 60 runs before the battery is spent, 0.9A for 1s is effectively 0.25mAh per shot consumed assuming there's not a higher depletion rate at that current even if it was a 10x depletion rate it would still not have drawn a significant amount (maybe getting 50 runs + latch openings before it's depleted)
FWIW, 5A at 5s is only 7mAh of consumption. The question is what's the depletion rate at that current? How many real mAh can it produced at 5A, and will it damage the battery?
At 5A, I question if it might damage the battery, at 0.9A I know the lithium's I've seen are rated for it, but not sure about the alkaline.
To pull 5A out you simply follow ohms law - V = IR so R = V/I -> 9/5 = 1.8 ohm So let's say you use 24Ga NiCr at 1.67ohm/ft you need just a touch over 1ft, or just under 2ft of 21ga at 0.83ohm/ft
You may want to look into what temp you need, what wire thickness you really want, and you may be able to get the current down a bit.