do i need a high powered alt.

With out the cap the voltage would drop so low when a extreme bass note would hit at high volume, stopped at a light that the car would stop, and some times it would stutter. The cap stopped that and drasticly reduced the dimming ot the head lights. But that is the daily driver. The othe car has the real stereo, Alpine CD player, 6 disc changer, Digital EQ, 2 x MRV-1000 (600w RMS each) Sub amps to 2 Cerwin Vega Stroker 12" subs, MRV-F400S (100w RMSx4) actual test sheet with AMP 165w x 4 @ 12.7 volts @4ohm CS-130 alt w/ice berg kit 200 amp stator, over drive 48mm pulley putting out 185 amps @ idle, 1-Farad Cap, 2 Optima Red Top batteries(800cca) front and Back connected by 1/0 gauge streetwires comp series power wire.

But you spent so much to stop that drop when a mere $15 would have done so much better. That's my point. Do a calc on how long that cap supplies current/voltage, or compare the Farad(s) you cap has to that of a battery. Of course it's not surprising that the amp voltage dropped without having done the big-3. Whether that would have solved or worsened headlight dimming depends on its wiring. It always gets me how amps that have an internal SMPS supply quote an output at a certain input voltage. What gets me even more is high-power amps whose output power is proportional to the input voltage (squared) - it's as if the amps are a purely resistive load! (I have a Kicker PCB which I've been meaning to decipher wrt to its SMPS circuit to see why it/they should behave that way, but that's another day project...) Is your other set-up's cap to protect the red-top, or to prevent dips? If dips, how bad are the dips without the cap?

The amps are analog V12 series DC to DC direct. So even with the optimas wired in series ie no isolation with a 300 anl fuse front and back with the 1/0 wire and the over built alt the lights and voltage will still dip without the Cap a couple of volts with the system turn up to stupid loud. The amps are fused internally with 2 x 20 4-channel, and 2 x 30 sub amp each. The voltage drop is almost gone and the lights barely dim with the 1-Farad Cap. So I got another Matching 1-Farad Cap but never got around to installing it yet. It not the overall draw causing the problem it's the surge when the bass kicks in the dip,spike causes the problem at idle even with the overdrive pully to spin the allt faster which is usually required for big amp alts.

I must be missing something.... Your batteries are surely not in series. [I presume you mean they are parallel but directly connected without an isolator. (Good luck when one of them fails.)] And "overall draw" - I presume you mean average etc? [Since the burb surge current draw is what is causing the dips.] Is the 2nd battery next to the amps, or electrically remote (ie, with +ve and -ve connection to the amp exceeding a few milli-Ohms)? Or conversely, when the 2nd battery is substituted for the cap - ie, same mounting terminals - how do the dips compare? As to the overdrive pulley, many don't have that luxury due to their high revving of engines and alternator physical RPM limitations. But that too supports my previous comment where many were worse off with hi-output alternators. (IE - they failed to consider their driving profile and alternator output curves.)     still_walkin - I hope this isn't hijacking, but at the moment I see as more proof of the pie.

No its fine its good to got to the middle someone's issue they Dont know they have besides I'm seeing how others wire their stuff up and learning more as well shoot for it1993 sdv

Alpine 4x6 6x9 5 1/4 swr-10d4

alpine v60

12.5 VGA flip down

Nettop pc w/10" touch screen

78nova

5-re audio 5x7 ,10" sub &

Xtx-500.5

"Take the faceplate off get the jumperpack"

oldspark wrote: I must be missing something.... Your batteries are surely not in series. [I presume you mean they are parallel but directly connected without an isolator. (Good luck when one of them fails.)] And "overall draw" - I presume you mean average etc? [Since the burb surge current draw is what is causing the dips.] Is the 2nd battery next to the amps, or electrically remote (ie, with +ve and -ve connection to the amp exceeding a few milli-Ohms)? Or conversely, when the 2nd battery is substituted for the cap - ie, same mounting terminals - how do the dips compare? As to the overdrive pulley, many don't have that luxury due to their high revving of engines and alternator physical RPM limitations. But that too supports my previous comment where many were worse off with hi-output alternators. (IE - they failed to consider their driving profile and alternator output curves.)     still_walkin - I hope this isn't hijacking, but at the moment I see as more proof of the pie.

Sorry I mis-spoke I meant parallel direct (+,+),(-,-) and yes the 2nd battery is next to the amps with the cap between the 2nd battery and amps ie + from battery to + on Cap to Amp distrubution block and the same for - connection with 1/0 guage ground from battry to chassis. When one of the fails? Just replaced both of them as they were 12 years old and weren't holding a charge any more with 2 more optima's. Had it wired direct from 2nd battery to Amps to begin with thats why I added the Cap. I always overdrive High-out put alts to boost the low rpm output because I have been doing this for awhile. The Ice berg kit for increased cooling of the alt with a hybrid ceramic ball bearing in the rear, to lengthen the bearing life span, as standard bearings don't handle the higher speed for that long in a 10x26x8. I have the alt built to the extreme limit of the cs-130 design it can handle with the Iceberg rear housing cooling kit.

You did well to get 12 years from an Optima. Let alone TWO in permanent parallel. You also replaced both which is essential an any permanent-parallel (or any series) configuration. (The number I see where "only the faulty" battery in a series string or permanent-parallel battery bank is staggering.) I'm still unsure why you added the cap, but its location leaves the voltage-sag issue unresolved. But I'll ditch that issue. I was surprised that another recent cap thread didn't get certain comments, but maybe others are tired of certain old issues.    Thanks for the info.

I agree I'm. Unsure as well in my experience with the red top I haven't had any issues at all let alone charging or keeping voltage up. My system has changed from being too many amps to reasonable and a red top has never failed me1993 sdv

Alpine 4x6 6x9 5 1/4 swr-10d4

alpine v60

12.5 VGA flip down

Nettop pc w/10" touch screen

78nova

5-re audio 5x7 ,10" sub &

Xtx-500.5

"Take the faceplate off get the jumperpack"

Yeah, normally I read how other batteries are better than Optimas, and cheaper (viz Kinetic, and more recently Deka stateside (long recommended here in Oz)). But it seems many chose the yellow tops when probably they shouldn't. IE - they should be using reds. And it's not uncommon that I read of long-life Optimas - though I recall only one 13-year old Optima and others reckoned that made it likely to get a free Optima replacement (LOL?) - and Lurch's were in parallel - ie, halving their reliability. But I certainly read more about Optima fails than anything else. And I note a trend where even those that have had certain "typical" Optima fails still swear by them (yet don't have other relevant battery experience). However, maybe the 13 year old and Lurch's Optimas are from the time when Optima was good, before their alleged demise into recycled or non-pure lead or copper or whatever increased their failure rate. Lurch's new red-tops will be interesting to life-cycle. Let's see - two times 3 months in parallel, that means both fail in 6 weeks LOL. (In that failure mode, 3 months would be valid.) But that 3 months was for yellows anyway.   (PS - NOTE that that's not an MTBF figure, it's merely a common fail time that I often read for yellows, and I cannot vouch for how good their charging systems or applications were - ie, it could well be a use fault.) Again, a voltmeter (across the battery terminals) is the best option. It'll warn of under & over alternator voltage, and low battery state. FYI - Optima for red-tops at 25°C (77°F) claim:- 12.8V OC fully charged (allow for surface charge depletion!).    13.0 to 15.0V alternator charging (yet 13.2V...) & 13.2V to 13.8V float. 15.6V with unlimited charge current PROVIDED the battery remains under 51°C (125°F) (IOW not for engine bays; I assume a 10A charging limit above 51°C.) And they are crankers, not deep-cycle.

As for mine I had it for 3 years and the reason I chose red or over yellow is I rather have better cranking that faster charging .keep in mind the car is a Cadillac and those things are all electronic so its juice hungry.1993 sdv

Alpine 4x6 6x9 5 1/4 swr-10d4

alpine v60

12.5 VGA flip down

Nettop pc w/10" touch screen

78nova

5-re audio 5x7 ,10" sub &

Xtx-500.5

"Take the faceplate off get the jumperpack"