You're starting from the wrong place. What are you trying to find out?
The batteries that you are using are 5V, I believe. The only way they could put out 10V is if they are wired in series. Which I suppose they might be, but it seems unlikely.
Anyway...we can assume a max of 5V and we know that you have a .3 ohm coil. Voltage divided by resistance equals current. So the answer there would be 16.7 amps. (5/0.3=16.7)
Power dissipation equals voltage multiplied bu current. 5V x 16.7a=83W.
You're starting from the wrong place. What are you trying to find out?
The batteries that you are using are 5V, I believe. The only way they could put out 10V is if they are wired in series. Which I suppose they might be, but it seems unlikely.
Anyway...we can assume a max of 5V and we know that you have a .3 ohm coil. Voltage divided by resistance equals current. So the answer there would be 16.7 amps. (5/0.3=16.7)
Power dissipation equals voltage multiplied bu current. 5V x 16.7a=83W
At 10V, the current would be 33.3a, so power dissipation would be 333.3W, which would be enough to make any hand held sized battery melt down or explode.
I am a tax guy, but I also have a degree in electrical engineering, which comes in handy on occasion.