Audio Systems: 16v battery/capacitor


Question
I am going to switch to 12v with 16.2 ultracapacitor in parallel with my 12v battery using diodes to keep the 12v battery from being over charged by the 16v. I already contacted the manufacturer of the ultracapacitor about using diodes to prevent over charging and they said this is a good solution because overcharging the 12v battery is a real concern.

It is a maxwell 58 farad.. true farads not like most of those audio supercapacitors on the market that are not really 5 farads but more like 200,000 uf inside them. So this one is bigger but still too small to run my whole car on it. It is rated at 21 continuous amps RMS with something like 800 amp capaibility for a few seconds bursts when needed. So 21 amps is enough for me to run the ecu and all its systems it runs from this supercapacitor, but I dont know if that will include the gauges and/or headlights when I go to wire it up. And I have read gauges and headlights are among the few components that may be burned out by the 16 volts systems some are running (usually they run 16v battery and replace their 12v battery altogether).

My question is... how do I find out if my stock gauges and headlights etc can handle the 16.2 volts? I know people use 16 volt batteries for audio and ignition/starter/ecu as they improve the performance of all of those systems but some have voiced concern about gauges and lights being burned out although few if any ever are reported. They say to check with the manufacturer of the gauges and lights ect... but this is crazy... my car is a 2000 mazda 626 2liter. Mazda won't give a crap to answer me and I have no idea how to even find the original manufacturer they got the gauges and lights from. Is there a way to test if it can handle 16.2 volts without damaging them? And what other compoenents could be at risk? I know radiator fans and fuel pump "like" the 16 volts. Hope you are familiar with this and I hope you don't tell me its not a benefit or its nonsense. I have friends with this set up and its improved their spark plug power and audio system and even start their cars faster. I just want to make sure I dont damage anything when I do it. They just hooked it up because they are nuts and most people have no problem switching without modifications. But I am more cautious.
thank and hope you can help

Jay  

Answer
I don't like the capacitor and battery idea, the devices have to be the same ,
all batteries up to 16 volts or all caps,  8 units 2 volts batteries will be better

you need to do this with all batteries  use 2 or 4 batteries  and  the accuvolt, this devices takes 12 volts and convert it into any voltage from 10 to 16.25
the input  voltage can be 10 to 12 and the output will be 16 all the time
but it takes more current, that is why you need more 12 volts batteries  

your car will support 16 volts max,the gauges will work but not accurate anymore   
the computer is not going to like anything over 15 volts,
you need a second small power supply  

read about this device, you are going to like

we use it for race vehicles and audio

http://www.jacobselectronics.com.au/raceaccuvolt.htm