Limit car battery current

[pidja105]

Hello,
I have a question,
can I use R = V / I formula
to calculate resistor for 41 amps and 12 volts?

 

[shrtrnd]

Yes, but what the heck is running at 41 amps in your 12V car?
Are we talking about starter amperage when you crank the engine, or is this another issue?

 

[pidja105]

No,
it is for my electronics projects.

 

[Alec_t]

So which project requires 41A?

 

[BobK]

Ohms law will tell you what resistor would draw 41A if placed across a 12V source that is capable of that current. This is not very useful. Tell us what you are trying to do.

Bob

 

[shrtrnd]

BobK is right. Trying to draw 41A for an extended period of time from a 12V car battery is not going to last very long.
More information will help us help you.

 

[Gryd3]

Hello,
I have a question,
can I use R = V / I formula
to calculate resistor for 41 amps and 12 volts?

Please note that this problem can be looked at one of two ways:

If your device is meant to pull 40 Amps, then it will only pull 40 Amps. You don't need to limit this, just hook it up if the device is rated for 12V.
Otherwise, if you are building a switch mode power supply, current/voltage limiting should be done on that circuit.
Finally. If you are concerned with 'Anything' taking more than 40Amps. Use a fuse. It won't dynamically turn down the voltage to stop you from pulling more than 40A, but it will still stop you from pulling more than 40A for any more than a second xD

 

[hevans1944]

Hello,
I have a question,
can I use R = V / I formula
to calculate resistor for 41 amps and 12 volts?

Sure. I'll even plug and chug the numbers for you: R = 12/41 = 0.29268292682926829268292682926829 Ω
How's that for service?

Your turn: what are you trying to do? What electronics projects? Please answer @BobK's question (post #5).