Alright check it out,

When I take an optima battery put it in the trunk I don't connect it to the front. What ya do is get an battery isolator. This hooks up to your alt and splits the power in two balanced loads. One load is sent to the primary battery(front). The 2nd load is sent to the 2nd battery. Now both batteries are able to charge. The isolator will balance 14.4 volts two each battery. With this mod its not possible for the front battery to drain.

 

It will keep the voltage constant but reduce the amount of amperage going to charge each battery. So if has an 80 amp alternator say the car needs 30 amps to keep the starting battery up to voltage. Say your pounding on the amp and its has a constant of 60 amps. Total draw = 90 amps. The battery powering the amp will eventually run out of reserve because you are drawing 10 amps more then what can be put back and the voltage will drop so low that the amp will no longer operate and no bass which is no fun, but youll still be able to start the car.

Now if the draw of the amp drops to say 10 amps, then there is plenty of amperage to go around and keep all the batteries charged. This is most likely the case because music is dynamic so the current draw will go up and down. The average is what is important not nessearily the peaks. With two batteries you probalby just have enough reserve so it doesnt have a chance to kill the battery before the draw lowers and it can recharge.

Say the amp draws 90 amps then the isolator will have to send all the amperage to the amp battery and have nothing left to send to the starting battery. Then the car will just keep drawing the 30 amps from the starting battery until no more left.

However its unlikely the amp will get anywhere near even 90 amps but if the fuse rating is 100 amps it is possible. It may not be likley but it doesnt mean it cant happen. You cant keep taking out more then what you put in and not expect to have problems eventually.

 

set your gains accordingly, if you havent already. do the big 3 in 1/0 guage. run a 1/0 gauge back to your monoblock and use a 4 gauge reducer or whatever. this is what i would do.

if you do this i am sure you will be fine. i also replaced my stock battery with an optima and my stock alt hasnt given my any problems

 

first of all thanks for the info guys

So let me get this straight if i put 1/0 guage wire in alternator positive to battery positive, battery negative to chassis, and the engine ground to chassis and get a second battery and isolator. If i did this it would be pretty hard to drain but it still could happen right? If i only ran the amp at lets say 1500 watts, which is the rms, could the batteries hold enough charge. I would think that it wouldn't draw 100amps if it was only running at about 60-70% of it's full power. Another question wouldn't it just be easier and cheaper to just get a bigger alternator lets say like a 160-175 amp one. Last question right now i have a t500.2 rockford fosgate. almost 1000 rms at 1 ohm but it's in stereo i believe. i have a 15in re xxx rms 1600 dual 2 ohm. how could i wire it with that amp to get as much power as possible to the sub and is it even enough to make the sub worth it? I apologize in advanced if i may seem like a noob to all of you, but i'm very willing to learn and appreciate what input you guys have

 

anyone heard of a capacitor?? hehe.. i would say a 2farad cap would definitely HELP against too much power draw from the amp.. it wont guarantee no failures, but it will help ease the stress on your electrical system.. get a good battery (optima yellow or red top) and a higher output alternator to go with it and you should be fine.. there shouldnt be a need for a second battery unless you are going for looks or something.. (my 2cents)

 

okay a cap will not work with him in this case. if his amp is continuously pulling an x amount of amps there is no way his alt will be able to charge everything else, it's a strain on the alt itself.

if you can afford a ho alt, go for it, its a good investment for your electrical system if you can afford imo.

 

did everyone NOT see the rest of my post.. i said "the cap WITH a higher output alternator and battery should do it".. not just the CAP by itself.. than my suggestion WOULD WORK IN THIS CASE, right?? i would rather do that than worry about running more wires through the whole car just to add another battery in the trunk (which you would have to secure there somehow).. its less of a hassle and probably the same $$$$.. wouldnt you rather have 1 alternator charging the cap and 1 battery than have 1 alternator charging 2 batteries?? just makes more sense to me, but all you other people are entitled to your own opinions..