It's not that big. Can it really be much more than a capacitor noise filter and maybe a Zener clamp to clip off high V spikes?
It's effectiveness has to vary inversely with the amount of continuous current being drawn from the battery. High end power amps use what's called a stiffening cap to prevent transient voltage dips at the amp itself. Is it like that?
Reality is merely an illusion, albeit a very persistent one. - Albert Einstein
Probably just a big Capacitor with low internal resistance that would make up for any poor battery connection and battery internal resistance. I have seen my alarm system and Radio/CD as well as the Scangauge get glitched when starting the engine in my xB. Looking at the positive terminal of the battery I can see why . . . I have no idea what is hanging off of it because it is in a position where it can't be viewed easily and the cover will not pop off. It may be a termination of several wires or a fuse holder for the car accessory load. In either case a good capacitor will help stabilize the voltage in a car and reduce noise and current surges.
jangeo was the closest. it stabilizes the voltage in the now this really only isnt a problem unless there is something creating electrical noise and current surges that trip up the ignition.
so what causes these problems? from my experience: big turbos on hondas. most cars have these built in. i know my car does, but if i were to put a sc61 turbo on an integra motor and put it in my car then it would probably max out my 'stabilizer' and an aftermarket one would be needed to help the car idle correctly and probably gain some efficiency strictly through smoothness in the ignition.
don't waste your time or time will waste you
The battery is really not an ideal power source when it comes to rapid transidents as the chemical reaction producing the power doesn't react that quickly. Audio amplifiers that have big bass pulses can produce drops in the power wires going to the radio amp - stiffner caps can be purchased with a 15 volt rating in the 120,000uf capacity cheep on the surplus market that are about the size of a big fist. Same thing happens in the 100amp controllers that I run in my scooter but it operates at 30-40khz so there are 3-18,000uf 63 volt low esr caps in parallel on the input terminals.