why can't my capacitor keep up?

I have 2 subs running from a 1500 watt alpine v12 amp. After absolutely destroying 2 alternators I decided to get a capacitor. It still can't keep up. I don't want to burn up another alternator. Will adding another capacitor do the trick or do I need a completely separate car battery?

What you need is a High Output Alternator. Capacitor is not the solution. Actually its another LOAD on the alternator. Spend your money on a good Alternator, Iraggi is good if you can afford it.

Lets not forget this either. https://www.the12volt.com/installbay/forum_posts.asp~TID~73496~PN~1 Completing the Big 3 is always a good thing and will give you a foundation to build your car's electrical system up to support your power needs.Still learning

Kraco

LOL!   Gotta love these magical caps that produce power out of thin air! Whilst a battery will hold up (not "keep up") longer, it won't prevent the alternator burning out. (It isn't a Bosch per chance?) Although a different brand of alternator may not burn out, as icearrow said above, you need a bigger alternator - one that can replace or supply the power used. (Though a capacitor is not an extra load on the alternator.) And of course you only do that after the big-3 as nodig suggested. It is even possible that little-3s (ie, the ground straps) cause the alternators to burn out - especially if they have external voltage regulators (but hopefully you have an alternator with an internal regulator!).

oldspark wrote: ...Though a capacitor is not an extra load on the alternator

Of course NOT . . .capacitors charge themselves.

I'm talking load - not charge. Charge a cap with a alternator and you probably will destroy the alternator - at least its diodes. When installed, the cap presents net-zero load to the alternator. The alternator has LESS load when the cap is discharging and vice-versa.    In fact that is one argument for caps - it means LESS load on the alternator as it filters out the normal load surges - lights, coils, etc, and greater electrical efficiency (albehat negligible). Not that caps are used that way - ie, to protect the alternator....!    A larger battery is similar, although unlike a capacitor, the battery has the added charging inefficiency as well as its float current (typically 1A for medium car batteries). And maybe lag. A capacitor is not an extra load for the alternator. If you think it is, look at the alternator's current waveform or measure its peaks with & without a cap during normal running. (Yes - voltage waveforms will also do.)

cruisin86 wrote: I have 2 subs running from a 1500 watt alpine v12 amp. After absolutely destroying 2 alternators I decided to get a capacitor. It still can't keep up. I don't want to burn up another alternator. Will adding another capacitor do the trick or do I need a completely separate car battery?

step 1: get a higher output alternator that equals the stock alternator plus the extra current that your amps draw(look at the rating of the fuses on the amp and add them up) step 2: make sure your amp's ground is solid and screwed to bare chassis metal step 3: take over the world!

soundnsecurity wrote: cruisin86 wrote: I have 2 subs running from a 1500 watt alpine v12 amp. After absolutely destroying 2 alternators I decided to get a capacitor. It still can't keep up. I don't want to burn up another alternator. Will adding another capacitor do the trick or do I need a completely separate car battery? step 1: get a higher output alternator that equals the stock alternator plus the extra current that your amps draw(look at the rating of the fuses on the amp and add them up) step 2: make sure your amp's ground is solid and screwed to bare chassis metal step 3: take over the world!

Don't forget the BIG 3 as well. It is a must with a H/O alt.

LOL! That's three times now... But it is amazing - the number of times the BIG 3 are NOT done! All those expensive OFC cables with zero-current circuit breakers and nearby extremely low ESR batteries, and there's a volt of more from the engine to the battery or chassis/body. And it heats up, and voltage increases, and heats some more - until it melts or the loads have just blown their protection fuses else their PSUs..... (Unless you have a single-wire D+ alternator....) As has often been stated, it's not uncommon for the Big 3 overcome the need for extra batteries (or bling-caps) or larger alternators.... (And as to damage prevention.... LOL!) Good on NoDig & JR for highlighting the Big 3. I'll bet that is what is destroying the alternators (assuming quality alternators). Alternators of 70A or more should handle the peaks, whilst those rated above 120A should power the system (depending on usage and other loads...)

Just to consolidate, first thing to do when adding a larger load to anything, meaning ANYTHING of course (houses, cars, bikes, or what have you) is the big 3. Always upgrade wiring to handle as much as, if not more, power as all of your loads combined. Example, factory wiring in a 92 civic is 10ga. power and ground. I have 1 12" sub powered by an orion 600d, and 8 spkrs@ 2ohm powered by a pioneer 640w amp. My battery resides in my trunk, with 4ga. from alt to distro block up front, 1/0 from block to batt, and 1/0 from batt to ground. 4ga. supplies all my amps, and nothing less than 14ga. for my spkrs. (tho i probably will never use that much power, never hurts to have the capability.) The factory alt was a meager 70A ouput max, (which meant it could handle 50A full time) My current alt is 160A max (probably something like 110A rms) and I still get lights dimming. My problem right now resides in my battery size actually, and the fact that my voltage drop thru my current wiring is too great (oops). The best thing to remember, i've found, when doing any work with electricity: if you think its enough (unless you actually do it for a living) its probably not, make it bigger.