Batt. or Alt....what do i need, i'm going CRAZY here!!!


Unregistered guest
i'm getting a jbl bp1200.1 amp and i need to know what i need. i was thinking about a 180A alt. but the guy at the audioshop in town said that a yellow top optima would be what i need. (they said the only 180A alts they could get would be ~$500!!!) and the batt. is $120.

i'm not going to hammer on the amp that much, i'm only driving an IDmax 12".

what should i do???

Silver Member
Username: Fishy

Tamarac, FL USA

Post Number: 508
Registered: Sep-04

Only thing a yellowtop will do is help you play your system longer while your vehicle is off.

If you have a Dodge, GM, or Ford there's plenty of places to get a cheaper 150-170 amp alternator.



Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4560
Registered: Dec-03
try or or

you can find 200A alternators for many cars for about $200-300.

to figure out what you need read this:

Unregistered guest
well, you say the batt. will help only when the car is sitting still. right?

i'm not gonna hammer on the amp, just trrin to get some low end, and idmaxes seem to be great for SQ. also i just got the bp1200.1 for ~$200.

u think i could make do w/ the yellowtop?
i mean this guy said he runs a JL1000/1 with the yellow top and a stock alt (in a Vet)and he has no troubles, also he is supposibly MECP certified. you guys think he's just a tard or is he right?

Gold Member
Username: Jonathan_f


Post Number: 2287
Registered: May-04
That amp alone is capable of drawing more current than most alternators can provide(including the Corvettes), not counting the vehicle accessories and computer that the vehicle has. The ONLY way to supply an amp like that is through a higher output alternator, the battery will do nothing to it.

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4579
Registered: Dec-03
I'm MECP certified as well, and I'd be willing to bet, at a higher level than your guy at the store. :-)
did you at least read the article I wrote and gave the url for on charging systems?
your 1200.1 will draw ~115A of current at full output, continuously.
most car alternators are only about 65-90A.
then figure what the car will draw itself for the motor, lights, etc.. up to 50A there.
if he's just swapped the stock battery for a deep cycle, it won't help except when the engine is off, he'll have a bit more time before he drains the battery.
it does nothing when the engine is running, since at that point, the battery is in charging mode with a forward bias voltage, and the alternator is the ONLY source of current for the entire car.

on a side note, if you don't crank the amp up to full output and just listen at normal, non-insane volume, you'll probably never really use a tenth of the amp's power, since every doubling of volume is an increase of power on a scale of ten.
this being said, you may never come close to using more than about 20-40A of current for the audio system and like your vette driver, you may be fine with a stock charging system.
wait and see.

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