Re: Stiffening Cap Theory

Great post, I have enjoyed it alot. Most newer caps have a two stage charging
system. I know that my cap goes into slow charge mode if it sees less the 10
volts. But I have seen the older non digital caps shoot out some good sparks.


Amen Brothas :)

To add to that, a charged device's ability to deliver "fast" current is
limited by it's internal resistance. The lower it is the "faster it can
deliver power" Most voltage drops at amplifiers can be cured by appropriate
wire sizing, then you now have drops across the whole board. If the drop at
the battery is the same as at the amplifiers you have large enough B+
wiring. A cap won't do squat.

A cap is in parallel with the rest of the electrical system, there is NO way
to isolate it without invoking a PN junction loss of a big-ass rectifier
diode. This means ANY sudden surge will be drawn from the power source with
the lowest internal resistance, be it the AC clutch, inrush of the headlamps
turning on, ABS, or even in my case the electric power steering.

Caps have a very low internal resistance (ESR) a battery's ESR is larger....
BUT battery technology is becoming better and better. The first and most
important thing is to have a battery that can deliver the goods really fast,
you can have a HUGE alternator and a shitty battery and still have problems,
the voltage regulators simply do not react with enough speed to compensate
for the audio related voltage drop. Now if you have a great battery and you
are still experiencing long term voltage drop or discharging then the
current alternator is not supplying enough charging current to bring the
battery back to a fully charged state.

Think of the battery as a water tank, it's not bad for the level to drop
below absolutely full, as long as the pump (alternator) can top it off in an
efficient manner.

Many times the blinking headlight phenomena can be solved with a good, fresh
battery. If you battery is dying in traffic then you need to look into a
larger alternator or find an alternate route home. Remember that
performance alternators will sometimes deliver LESS current than the stock
counterpart at idle, they can also at times be MORE electrically noisy.
Updating to a performance alternator without getting the rest of the
electrical system "ready" for it can be like shooting yourself in the foot.

Another commonly overlooked item is the grounding coming from the battery.
Normally this consists of a heavy ground wire going to the engine block
terminating near the starter (the stock vehicle's largest current consumer)
then there is usually a much thinner wire bonding to the chassis, then
engine is usually bonded to the chassis or sub-frame via a braided wire but
sometimes not. Many of my problems were solved by adding to the stock
grounding system. I took 4GA (Not a big system in retrospect to some) and
ran from the negative to the transmission then to the fire-wall (FWD car).
I also ran a 4Ga to the alternator mounting. My headlights would dim when
the AC clutch kicked in, ABS activated, etc. With a stock electrical system
this no longer happened after updating the grounding system.

I have seen too many 0 gauge wires going to a positive terminal and a 10 GA
coming from the negative to the chassis, at times that 10Ga would get DAMN
HOT!

I have seen caps cause problems too, things people overlook. In a
discharged state they will appear as a dead short to the charging device,
moreso than a battery. Remember ESR, the less charge the lower the charging
impedance. If you are HAMMERING a cap this can cause alternator problems
down the road due to increased inrush loading. Another problem is what
happened to me. A lady was driving her son's car while he was off to
school. The had a bank of caps in that bad boy that looked like a case of
Fosters. She did not know this and I did not know this. She left the
lights on and killed the battery on a shopping "mission" I was in the wrong
place at the wrong time when I offered her a jump start. When I connected
that last connection to the ground of my car I saw a flash I can still see
when I close my eyes (J/K) I had to cut the negative clamp off my jumper
cable with a Swiss army knife and remove the clamp from my engine with a
cutting wheel! A car battery can deliver more current than a welder when it
needs to, mine felt that it needed to into a bank of caps that would hold
reserve to the Hoover dam.

So, MOSFET or anyone else with large caps. You may want to place a bit of a
warning near your battery incase your wifey takes the car to the market and
leaves the lights on :)

Chad


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