# Thread: Do I Need To Beef Up My Alternator Or Anything Else

1. Originally Posted by tech180
One thing to also consider is there will still be power running through the lines (Just possibly not the full current required or fluctuating ). Maybe I will come up with a way to do some testing on this and see how long the caps will last at different voltages running through the lines (Removing my car PC off the line first, lol).
Right, the above 0.3 was assuming there was nothing on the lines. However that also means it will be even less time until the voltage at your PC gets down to the 6-8 volts your car is at while cranking. Capacitors are a bandaid for a bigger problem, not a solution to really anything. It would require 10,000 farads to equal the capacity of a AA battery just for a comparison of energy storage capabilities

Also.. if you're getting whining or popping while starting your vehicle.... well keep in mind there's a REASON why factory radio systems shut off when you start the vehicle. It won't hurt the computer if you have a proper power supply (m2atx or the like) though. If your carpc is shutting off when you crank, and you have a DC-DC psu, then there's either something wrong with it, or something wrong with your electrical system.

Edit: Whups, I had my math inverted. That actually works out, 80F at 20amps is 0.25V/s, which would give you at least 5-6 seconds of power before it dropped to cranking voltage. Who knew.

On an amusing side note, a spare battery is orders of magnitude cheaper you know :P

2. Originally Posted by malcom2073
Right, the above 0.3 was assuming there was nothing on the lines. However that also means it will be even less time until the voltage at your PC gets down to the 6-8 volts your car is at while cranking. Capacitors are a bandaid for a bigger problem, not a solution to really anything. It would require 10,000 farads to equal the capacity of a AA battery just for a comparison of energy storage capabilities

Also.. if you're getting whining or popping while starting your vehicle.... well keep in mind there's a REASON why factory radio systems shut off when you start the vehicle. It won't hurt the computer if you have a proper power supply (m2atx or the like) though. If your carpc is shutting off when you crank, and you have a DC-DC psu, then there's either something wrong with it, or something wrong with your electrical system.
I agree :-) I still believe they are a good thing to have, not to band aid a power issue but to protect your computer from power spikes and drops. They also help with line noise a bit.

Oh, and they are bling bling yo. j/k

3. Originally Posted by malcom2073
Right, the above 0.3 was assuming there was nothing on the lines. However that also means it will be even less time until the voltage at your PC gets down to the 6-8 volts your car is at while cranking. Capacitors are a bandaid for a bigger problem, not a solution to really anything. It would require 10,000 farads to equal the capacity of a AA battery just for a comparison of energy storage capabilities

Also.. if you're getting whining or popping while starting your vehicle.... well keep in mind there's a REASON why factory radio systems shut off when you start the vehicle. It won't hurt the computer if you have a proper power supply (m2atx or the like) though. If your carpc is shutting off when you crank, and you have a DC-DC psu, then there's either something wrong with it, or something wrong with your electrical system.

Edit: Whups, I had my math inverted. That actually works out, 80F at 20amps is 0.25V/s, which would give you at least 5-6 seconds of power before it dropped to cranking voltage. Who knew.

On an amusing side note, a spare battery is orders of magnitude cheaper you know :P
Wow, 5 to 6 seconds, man, I never would have guessed that! Yeah, they are pricey for sure. Think I paid \$90 each. I however made them the last purchase, after my 220a alternator, optima battery and 0g wires all around.

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