24v?

[mcar451]

so currently i have a 180amp high output alt but im still getting dimming of the lights due to my voltage droping from 14.5v to 12v when the bass hits. i have done all the wire upgrades, big 3 and such, and none seems to totally eliminate it. what crossed my mind is increasing the voltage so that it would not have to draw as much of a current. is there any safe way to run the car off of a 24v system by wireing 2 batteries in series?

[zxtwou2]

no...you don't want to exceed 16vdc on a 12 volt system. in fact, running at even 16vdc for too long will damage some of the more sensitive electronics in the car.

[mcar451]

hmm is there anyway to have the sound run off of a 24v batt and charge off the alt yet keep the remainder of the car on a 12v system?

seems a bit far fetched, but im thinkin of maby a reducer, to step the power down for the car or step it up for the batt

[zxtwou2]

yeah, there's a way....let me know what you have in mind and i can possibly make you a diagram.

[JonsZX2SR]

There are ways to get the system to charge a 7 cell (14V) or 8 cell (16V) battery but they are expensive. basicaly you would need a DC-to-DC converter, 12V to 15+V ot 17V+. With 40 to 50 A capacity this is going to run hyndreds of dollars.

Before you go there, try putting a good capacity motorcycle or tractor battery close to the amplifiers and after the power cable.

The idea is the local secondary battery with provide current for peak demands of the amplifiers and keep voltage at the amp end close to if not greater than 13V. This means the current drawn down the supply line to charge the 2nd battery. The other end of the supply line should be connected directly to the front battery. The battery provides current during peaks in a manner that is called peak shaving.

The front battery and alternator should each have a 2nd, massive ground wire. If you are relying on the stock engine to chassis ground it probably isn't large enough to provide the required path for current.

Note that current flows from the negative terminal, theough ground and chassis connections, etc. The positive side of the system is the return.

Since the constant current draw from the system to the amplifier cluster is determined by the voltage drop across the supply line, current peaks would be eliminated and the dimming problem avoided.

If this doesn't help, then a) you have a bad ground or connection somewhere (alternator to chassis ground is oftern a problem) b) your audio system is massive and the 180A alternator you bought is over-rated.

[jdrzx2]

Capacitors aren't really that expensive, I'd rather use one of those than an extra battery. Most of them have digital screens that tell you what the charge is anyway, and they look cool.

[mcar451]

im not looking for cool, im looking for something that works. currently i have a 180amp alt, 4ga and stock wire runnin from the alt to the bat. 4ga from the alt to the chassis, 4ga from the batt to the chassis, and 4ga from the batt to a distrubution block in the back. from there i have 2, 4ga wires commin out going to a jl audio 300watt 4 channel amp and another to a jl audio 1000watt monoblock amp. the 300 and the 1000watts are rms powers for the amps. also each amp has a 4ga ground commin out of it to the chassis. one thing i did learn the hard way today is that the 4ga is not big enough. it overloaded and caught fire at the alt connection. not good. ill be replacing the wires from the alt to the bat and the bat to the block with 0ga wire as well as the grounds. in addition i think im gonna add a 2farad cap at the back to help regulate some of the power. idk if this will work or not, but let me kno what u think

thanks
Matt

[chasingsafety]

what about alternator overdrive? That should sort out your voltage drop at idle.

[mcar451]

im not to worried about it at idle, its more of an annoyance/not good when the lights dim while driving down the road at night

[droptoutzx2]

with the bigger wire that may help also anything to cut down on your cars draw, as in led bulbs i wouldnt use a capacitor i would go with another battery or 2, this might sound crazy but you might want to see bout riggin up another alternator if thats an option for ya

[chasingsafety]

when I switched to all led's and HID's my voltage rarely drops much at all

[mcar451]

only deal with that is i would most likely have to remove the a/c which i really dont wana do

i like my a/c =]

the only reason im even concidering a cap is so it provides power fast when needed and charges when power is not needed... basically reducing peaks and valleys in the draw that the system is taking. although a batt would be good, it does not dilever power nearly as fast

also i eventually wana do a HID conversion but its a bit outta the price range right now

[chasingsafety]

it sounds like in this case, a cap might be your best bet. Your car is supplying enough power, the problem is the amp is hitting to hard, and fast for your alternator to compinsate for your batteries loss in power.

Normally I would say a cap is not needed, but it sounds like it is in this case

[mcar451]

i certainly hope so, beacuse if i put it in and it does not work, then im going to have to get very creative. i also did a few calculations last night based on the alt runs the car at 14.5V my final calculations said that assuming that the system was maintaing a constant draw of 1300watts rms and to be safe 2600watts peek, and also assuming that the car drew all 95amps that the stock alternator was, then my alt is between 5 and 40amps to small. however in most cases beacuse music verys drasticaly in frequences the system is rarely using all the wattage constantly. the point of this is if i wanted to be totally on the safe side, upgrade to a 250amp alt, but i have no clue where to get one. also as i stated before, if the batt cannot deliver the power to the amps fast enough, then a cap might help, or so i hope

[ZX2R]

Batcap is the answer for you. I have 2 1100d's (800 Rms a piece), 1 4500 (300 Rms) and an 1100D5(900 Rms). I run 4 GA from the front batt to the rear, and NO wire upgrades. Not even the big three at the moment. I haven't had the lights dim(even at Idle) since I installed the batcap, whereas before with 1 1100d and the 4500 my lights would dim all of the time. Of course I have the second largest batcap available($300). Look up Xstatic on ebay and you'll run across them. Here's the one I purchased.
http://cgi.ebay.com/Xstatic-Model-2000-Stereo-Battery-35-lb-BatCap-New-2008_W0QQitemZ130183365215QQcmdZViewItem?_trksid=p 3286.m20.l1116

[JonsZX2SR]

An overlooked problem is how fast can the alternator respond to changes in current demands ?? There is a huge amount of inductance in both the stator and rotor coils.

If the change in current demand (for example 40A constant to 120A transient) occurs over a 100-200 msec time scale and the alternator takes 1000-2000 msec to provide full current demand, there is no way the alternator can provide full instantaneous current. If anything a larger alternator would be expected to have greater inductance than the OEM unit.

Batteries also have problems responding, the electrochemical reaction doesn't switch on stantaneously. This is the reason supercapacitors were developed, which can release current (and therefore maintain voltage) in under 1 msec time. However batteries are usually faster than large alternators.

My suggestion is to locate a good motorcycle battery near the amplifiers to provide a source for the current spikes. This should reduce the problem. If there is still a reduced effect, try putting a 1 Farad capacitor in parallel with the 2nd battery near the amplifier location.

[mcar451]

well it turns out that when my wire overheated and caught fire, it caused damage to the alternator. so the 180 amp alt is out... in experimenting around at the local alternator shop we got the crazy idea to use the van style alternator but rewind it, so now i have an alternator pushing well over 200 amps up front. i was gonna put a 2 farad cap in before the distrubutoin block so that it can supply power to both the amps. also i am going to upgrade the big 3 to 1/0 guage wire so there will be no chance of it overheating again. if this does not all work, finally ill put the motorcycle batt in the back in parallel with the 2 farad cap. hopefully this all works and ill keep u guys posted thanks for all the input and if you might have any other suggestions feel free to share

thanks
matt

[blue_2001]

talk to serious he might be able to help u

[JonsZX2SR]

in experimenting around at the local alternator shop we got the crazy idea to use the van style alternator but rewind it, so now i have an alternator pushing well over 200 amps up front.

It isn't as simple as rewiring the static and rotating coils to provide more current, you will have to modify the voltage regulator to handle additional field current. You may be disappointed with the results, you may blow up the voltage regulator, or you may see voltage spikes when current demand changes that damage the rest of your electrical system. Put an oscilloscope on your electrical system and watch for transients.

A slight increase in capacity (say +20%) and reprogramming of the voltage regulator might be all you need to keep the system charging down to engine idle speed. Dealing with current demands during audio peaks is a separate problem.

This may sound counterintuitive, but if you put a good sized battery and capacitor at the amplifier end of the electrical system you may want to REDUCE the size of the feeder wire or possibly put a big honkin inductor in series to reduce current draw from the rest of the car on transients. This would reduce or eliminate voltage sag on the car side of the system while allowing the 2nd battery to recharge between peaks when current demand is less.

Done correctly you may find a 4, 6 or 8 Gauge feeder is sufficient to prove steady current, if you can eliminate the need for the rpimary battery and alternator to supply peak current demands by the audio system.

The reason this works is an effect called peak shaving (which I've studied for elevator electrical systems) where the feeder is called on to provide constant operating current (including averaged recharge to the battery) and all the peak current comes from the local battery and capacitor.

Obviously this won't work for a competition audio system, but it should easily work for a typical large audio system on a street driven car.

What happens is current flow down the feeder is enough to recharge the battery betwen the peaks and the increase of current flow is 10% or less during the peaks, with the difference coming from the capacitor and battery.

[mcar451]

wow, this has been very helpful, although a bit over my head. i noticed that your location is connecticut, jonszx2sr, im also from connecticut, is there any way that i might be able to meet up with you in person to go over some of this?

thanks
Matt

[mcar451]

well you were correct in the assumption that i may be dissapointed. while not so dissapointed as in the fact that the lights are still dimming after replacing wire and the alt, i am still curious as to see what might happen if i were to introduce a 2 farad cap into the system in the back before the distrubution block so that is supplies power to both the large sub amp and the smaller mid's amp. if i am still noticing an effect, then i might as you have stated many times introudce a battery into the back as well. the only concern of mine right now is that i dont want to clutter up the back to much. i would perfer a cap over a second battery.