okay so i recently installed a 1700 watt lightning audio system into my car. ever since then i keep having power problems. i recently had to replace my battery because i just couldn't jump it again. (7th time) my question is, if i install a second battery say, in the trunk, and route all the add-ons to that battery and leave the other one to just power stock parts like lights and starting the car, will that take away the risk of the amps draining the starter battery because i do blame them for the battery dieing even tho i make sure the switch for them is off.
then if so. do i need to match the battery to the starter battery as in like 500cca. am i wrong in thinking that the allternator powers the whole system anyway. does it really matter the size of the battery that acts as the pass-through?
They both matter.
Your battery is a storage tank, so to speak, for instantaneous demand.
Think about it this way, if you have a bathtub filled to the top with water, and you have a fire in the living room, which would you rather do...run back and forth with a five gallon bucket and dip it in the full tub to quickly get your water supply, or go to the faucet and wait for the spigot to fill the bucket up each time?
You'd probably be more efficient if you had a full tub of water waiting on you, right? And the bigger the tub, the better. Same with your battery. You have an amplifier and speakers that are power hungry and will drain your battery very fast. Better to have a battery than can deliver the power.
But I said you need both, a high capacity battery and a better alternator. Think about your bathtub. If you have a big fire and you keep running back and forth to the tub, eventually the tub will be empty and the fire will still be burning. You need a spigot that replenishes the water as fast as you take it out. So, you'd prefer to have the spigot delivering high water pressure and flow, refilling the tub each time you run back and forth with the bucket, right? If the water pressure is too low, it might take longer but eventually you will be faster with your bucket and the tub will be empty and you will be having to wait each time with the bucket to let the tap fill it up.
Same thing with your alternator (the spigot, metaphorically)...If your stereo amplifier and speakers are demanding power, even from your big battery system, it might take a long time, but eventually the alternator won't be able to keep up and the battery power will not replenish quickly enough to maintain your demand.
Replace both, and on a side note, you can't have a special battery JUST for your starter and another one JUST for your stereo. By the nature of the beast they must be in parallel and be recharged by your alternator, unless you are willing to recharge the stereo battery with an AC powered battery charger in your garage, and then you would only be able to listen to your stereo for an hour or so tops before the battery died on you and needed another charge.
BTW, as an old coot, not that old but old enough, I suggest you quit dumping your hard earned money, (or your parent's money) into $2000 stereo systems that will do nothing in the long run other than ruin your hearing and get you citations from the police, not to mention rattle and vibrate all the interior moulding and fasteners in your vehicle to the point it is worthless. If I had one dollar of every ten I wasted as a teenager and 20something I might actually be debt free today and have a lot less stress. Hard to see that right now, believe me I know. Take my advice for what its worth.