good enough alternator??

[marv554 10+ year member]

hey,

i went to my local car audio store cause im looking into getting a pair of 15" type r's along with a US amp Merlin MD2. Im gonna be putting about 750 watts to each sub, so 1500 in total. The guy that helped me out at the store told me that i would need a capacitor because my electrical system wouldnt be able to handle that. ive searched this forum and all i read is that a cap is the biggest waste of money there is. im driving a benz S320 and the battery is in the trunk so it would be really difficult for me to perform the big 3 due to the fact that i cant connect the new wires from the battery to the alt unless i basically take apart the interior. so i was wondering if my car maybe already has an electrical system that would be strong enough to power this amp. i know that basically the alt completely takes over after you start the car and the battery is used minimally. the specs that i found on the alt on my car are 14 v, 115 amp. do you guys think thats strong enough to power the system? or should i go for the cap? thanks for your help, i appreciate it.

Click to read more...

 

[swc204 10+ year member]

it should be powerful enough

i have the same amp and there very efficient so they wont **** up alot of juice.

you could pm flakko to get a great deal on that amp if you wanted to save some money.

 

[VOA_NIGHTMARE 10+ year member]

I personaly would add a second bat if you already have yours in the trunk this would be very easy to do and effective. I didnt do the big 3 and I threw in a 2500d and added 2 bats my lights dont dim and my volts are always the same now everything runs so much better. I dont know if the alt can take it and if it can for how long but I wanted to test the amp out.

 

[Savstyle 10+ year member]

you should be good with that alt

 

[marv554 10+ year member]

thanks for the replys. do you guys think that maybe i should get a 2 farad cap just to be on the safe side?

 

[Johnny Drama 5,000+ posts]

Most alts have ~40% reserve

115a*.40=46a reserve

to find peak amperage draw...

W/V=A

1500w/14.4v=104a MAX draw. Just know that your setup will be capable of drawing that much power on certian notes and music, it may not be a long period of time but it is possible.

A second battery, or cap can help. An upgraded alt would help the most.

Hook everything up, if you get dimming, upgrade. If you dont, no worries.

 

[helotaxi 5,000+ posts]

to find peak amperage draw...

W/V=A

1500w/14.4v=104a MAX draw. Just know that your setup will be capable of drawing that much power on certian notes and music, it may not be a long period of time but it is possible.

Actually it is a lot more than that when you figure in that an amp is usually around 60% efficient.

104/.6= 173A

Given you won't even see the 104A with music, much less the max draw but the amp can draw that much current.

 

[marv554 10+ year member]

Actually it is a lot more than that when you figure in that an amp is usually around 60% efficient.104/.6= 173A

Given you won't even see the 104A with music, much less the max draw but the amp can draw that much current.

so what do you suggest?

 

[helotaxi 5,000+ posts]

Well there really is no way to know. We don't know how you listen to your music. That will determine how much current the amp draws and whether your electrical system will be adequate or not. Any way you go, you need to upgrade the wire to the alt, especially seeing as it runs the entire length of the car. With that long a run, voltage loss to resistance can be significant and the power is lost as heat. Draw enough current down too small a cable and you will have a fire hazard on your hands. The interior has to be somewhat taken apart to run signal from the headunit to the amp, and speaker wire from amps to front speakers. While it is already apart, run a new alt-to-battery cable.

If the alt is not adequate, adding a cap will only make things worse. Don't do it.

 

[n2audio 5,000+ posts]

...i would need a capacitor because my electrical system wouldnt be able to handle that.

Just plain wrong.

There are those who believe caps have their place, and I don't argue that opinion, but "your system wouldn't be able to handle that" should be followed by -- "So a cap would be a useless, and possibly detrimental upgrade".

He's just trying to sell you something.

Being a high quality class D I would think that amp is on the high side for efficiency - maybe 80%. With an alt that size and a car that nice I see no need to to touch anything until you determine you need to make changes.

I wouldn't be surprised if it runs fine.

 

[da12b 10+ year member]

check out http://www.bcae1.com

you will learn a lot. I garentee it!!!!!!

 

[FoxPro5 5,000+ posts]

I pulled 2K on a stock 80 amp alt with upgraded battery and big 3...with NO CAP....I did get teh dimms at loud volume with strong bass hits. The only way to know for sure is to try and see. I wouldn't suggest getting a HO alt prophylactically if that's what you're asking.