Adding a capacitor to a Car Audio System?

[ArchangelX]

Hi all,

I recently got my FD back up and running, but I'm running a VERY tiny battery now. I have a new battery tray setup that pretty much allows the room for a larger intercooler setup, but my battery is tiny as a result.

I have two 12" Infinity Kappa Perfect subs in my trunk, along with 2xJBL BP1200.1 (1200watts each) amps. Kinda an old system, but it only has a few hours of runtime through them, so they're still great.

Anyways, because I've got this sound system, plus all the tweeters and stuff in my cockpit, I kill my battery every single time I amp it up for awhile. I'm an Audio noob, though.

Isn't there some sort of capacitator I can get so that I can run my system without killing my battery, plus be able to run the car with the engine off? Thanks for the help!

[Nuckin Futs]

Car Audio Power Capacitors

Power capacitors or Stiffening™ capacitors are used to assist an automobile that has a problem with dimming lights (voltage sag) or to help tighten up the bass. These capacitors store a large amount of power and then release it very quickly when the demand is the greatest from the amplifier. These capacitors release the current much faster than a battery can and do not force the amplifier's power supply to be at a loss when bass notes and other transients are greatest. Capacitors should be chosen in the ratio of one Farad per thousand watts
Besides adding another battery or getting a battery with more reserve power I'm wouldn't know what else you can do.

[Udrivecrap]

i'd add another battery and put one of those capacitors and run the stereo off that one alone so when the car is off it drains the spare batt and not your engine/start batt. i remember seeing those photo cell things you can charge your car battery with, i dunno how many volts/amps they produce... like if you're hanging at the beach and you pound your sounds for a while and then you gotta push start :gapteeth: i've done that, it sucks.

or disconnect the big azz speakers and amps and just listen to the radio through regular speakers and save your hearing... sounds like your battery will still be insufficient. that's why i would add another battery and maybe a higher output alternator (if available) to handle charging both batts. :sailor:

i dunno, i'm kinda new with all the new stuff nowdays :crazy2:

[ArchangelX]

That's what I'm thinking...just another battery, maybe. I was doing some online reading, and I saw some batteries that are specifically made to act like capacitators, but have tons of storage power. Not too expensive either. I've got two nice bins in the back where I can mount them as well. Hmm.

I'm already deaf...so that's a negative on that last one, anyways, Dave. :hihi:

[Act162this]

[disclaimer] i'm by no means an expert on this, and it's been years since i messed around with car audio, but here's my .02... [/end disclaimer]

you may want to consider adding an Optima Yellow top (or blue top, if you have the space) in the back right corner (to compensate partially for weight of driver).

invest in good, large gauge cable for the long run from front of car to rear.

Add a battery isolater so that your starter battery cannot drain this battery and vice versa. You can use a fancy one that will allow you to use the Optima as a starter/booster battery, in case starter battery fails (you can use it as a starter, or a jumper).

Add a 1f (or two 1f, one for each amp) capacitor to the system linked to the Yellow top.

If you plan to hit it hard a lot, or play music with the motor off, consider investing in a motor maul.

[Udrivecrap]

wow... you sound like an expert :gapteeth:...

relocate the battery and make it bigger! :pirate1:

[ArchangelX]

[disclaimer] i'm by no means an expert on this, and it's been years since i messed around with car audio, but here's my .02... [/end disclaimer]

you may want to consider adding an Optima Yellow top (or blue top, if you have the space) in the back right corner (to compensate partially for weight of driver).

invest in good, large gauge cable for the long run from front of car to rear.

Add a battery isolater so that your starter battery cannot drain this battery and vice versa. You can use a fancy one that will allow you to use the Optima as a starter/booster battery, in case starter battery fails (you can use it as a starter, or a jumper).

Add a 1f (or two 1f, one for each amp) capacitor to the system linked to the Yellow top.

If you plan to hit it hard a lot, or play music with the motor off, consider investing in a motor maul.

I have no idea what a motor maul is, but I'll go look it up. Thanks! :D

[Act162this]

sorry - just had a thought. how tiny is the battery you are using now? tiny like a motorcycle battery?

you could probably swap out the battery with the smallest optima or other gel-cell battery you can find, and that should be okay with a capacitor. the capacitor is going to store and release energy when the amps need it, but if your battery is dying when you crank it up, your alt. might not be up to the task as well. are your lights dimming when the bass hits? if you keep the rpms up when you're cranking it up, do the lights still dim or does your battery die?

you may want to consider a deep cycle battery over a starter battery if you're going to go with a single battery. i ran a single Optima Yellow top for many years, and pretty much abused the heck out of it with no problems starting at all.

I *think* I saw a 5f capacitor at Island Sound when they were going out of business, so I know they exist. probably quite expensive, and probably overkill. a 1f capacitor should get the job done.

there's a shop in Waipahu just down the street from ESH and 4WP that sells all kinds of Optimas (that's the only place I could find reverse-terminal red tops for our Toys). I think Pro Comp also makes gel cell batteries of different sizes. If you go with a gel batt, you can squeeze it in anywhere you can fit it, regardless of orientation (can't spill).

the motor maul, in retrospect, would probably be overkill for your application. they are quite popular with the cb crowd that run outboard amplifiers, which require a lot of juice (highly, highly illegal) and multiple batteries (think lowriders with hydraulics and trunks full of batteries. not everyone is willing to add extra alternators under the hood, or sacrifice their a/c to swap it out for another h/o alternator, so the mauls are popular with that crowd. i don't think your two amps will be drawing anywhere near that kind of current.

sorry - kinda long post... but just a couple of other thoughts.

[ArchangelX]

I appreciate the deep thoughts...and yeah, I have like a lawnmower battery for my vehicle, because I wasn't able to find an Optima at the time. So I'd like to move to an Optima, as that's what the tray was designed for.

I imagine if I got one, it might fix my dying battery problems. The alarm actually pulls power when the car isn't using it, and it drains it as well. I have to run the car every couple of days or the battery dies as well.

I think it's the battery size. I need to upgrade. But I would like to be able to play when the keys off, though...

[taegu808]

a big heavy sound system is against what the FD is about IMO but to each their own (and yes I know mazda itself put in that crazy bose system in the tourings, I had one). in addition to a decent battery you may want to look into a rewound alternator. capacitors are only for short term power hits like deep bass notes, not to run the system with the car off. or a sneaky anti-theft surprise.
:)

[Act162this]

rewound alternators could be a good idea too, if your charging system can't keep up with recharging the battery while drawing on it.

They also might be a help if you have an alternator about ready to go south (gotta rebuild/replace anyway, and for a little extra $$$).

There's a place down here that does pretty good work down on Nimitz (something like Pacific Starter and Alternator) or something like that in a green building kinda across Puuhale School. Spoke w/ the owner a couple of times when I needed alts rebuilt for specific apps. You purchase a rebuild from them, and provide your core so they can rebuild/rewind that for the next guy. If they don't have your alt in stock, you can leave your core w/ them.

Only thing is, don't go too crazy on upping the amps. Increasing output increases heat, which can shorten the life of your alt. Second thing is that this increased output comes at higher rpms, but your idle output might actually be *below* your stock alt. output. i.e., if you buy a 140 amp alt, you might only get the full 140 at like 4000 rpms. at idle, you could have less output than stock.

I would hazard a guess that at this point in your system, you don't need a PowerMaster or Leece-Neville alt, so save your $$$.

Work the problem first, try switching batteries and see what happens before going to dual batteries or upgraded alt. Then add a cap if you see your lights dimming on the big bass hits. If you crank it up and your motor bogs w/o giving it gas, you're putting a big load on your motor...

[ArchangelX]

My sound system is designed to be removable. It lifts out as one piece. Stealth, too. For track days. :D

I don't street race, so there's no reason for me to worry about it when I'm just cruising. ;)

Woah. Posted right before me! Anyways...yepz, I'll work the problem first with a better battery. Optima is probably all I need for the moment. Thanks for the great discussion, guys!

[Act162this]

capacitors are only for short term power hits like deep bass notes, not to run the system with the car off. or a sneaky anti-theft surprise.
:)

Heh... yes... the 1f cap makes for a sneaky surprise. I have heard that this can constitute a mantrap or booby trap, and could be illegal (kinda like the shotgun shell under the seat or razorblades by the hood release or under the door handles thing).

only caveat being that in HI, where the theives have more rights than the victims, you could get sued for having a mantrap, and they'd win. they get your car or your accessories, and your $$$.

My sound system is designed to be removable. It lifts out as one piece. Stealth, too. For track days. :D

Woah. Posted right before me! Anyways...yepz, I'll work the problem first with a better battery. Optima is probably all I need for the moment. Thanks for the great discussion, guys!

smart. i got so tired of removing everything for auto-x back in the day that i eventually just mounted my amp directly to the sub box, and used quick-disconnects in line for the power and signal cables.

ghetto, but saved me lots of time. there were days that i just didn't go to the auto-x b/c i didn't want to deal with stripping down the car, but that was a time-saver.

[beefy242]

Heh... yes... the 1f cap makes for a sneaky surprise. I have heard that this can constitute a mantrap or booby trap, and could be illegal (kinda like the shotgun shell under the seat or razorblades by the hood release or under the door handles thing).

only caveat being that in HI, where the theives have more rights than the victims, you could get sued for having a mantrap, and they'd win. they get your car or your accessories, and your $$$.


they shouldnt be able to sue me for too much after taking 2 or 4 12 ga. blasts to the chest (double-barrel O/U) and/or face.

[xurusaibobx]

batcap/kitnetik.....


damm that jbl amp the one thatlooks like a lego? that amp is kickassss old skoool...very good amp

[ikeyballz]

i used to have two 12's in my trunk, 800 watt amp.. id blast it for half an hour or so w. no prob.. never did have to push start it.. my battery was huge tho, and i have a heavy duty alternator..

[AfricanHerbsMan]

bigger anlternator

[Shinigami052]

Hey Mike IDK if anyone answered your question yet but I'll give my 2cents (being an electrical engineer)

A capacitor (cap) won't help your problem. The caps are there to stabilize the system (since while running the car, punching the gas, turning on windshield wipers or your lights will drain power from the rest of the system) the cap is there to stabilize and regulate those power influxes. The cap won't hold a charge for very long after your car goes off. In fact, the cap will drain your battery faster because there's a lot more power that the system needs to charge the cap when it's drained and the the cap wastes a lot of energy while discharging and doing nothing.

The only thing i can see you doing is: get a bigger battery or get another battery.

[corytomo]

^^^ yep hes right. If your lights dim while pounding that bass, you probably need a cap. But if you have a tiny battery, that's what the problem is. Optimas rule.