Cost Saving Idea

[TeamHT]

I'm still trying to find the logic...even if we ignore the incorrect science you're still using two batteries...so where exactly are you saving? You havent saved anything, just separated the loads (Giggity) which is actually more inefficient.

If your batteries are dying then we got a bigger issue than trying to save money on batteries

[RF4LIFE]

I ment if you put two batteries with same voltage, 1.5 or 12, and different amperage the smaller amperage will be overloaded

[RF4LIFE]

I also ment when the car is off you could run it on one battery and start the car on the other battery

[TeamHT]

I do not understand peoples absurd fascination with running a system with the car off. That is one of the most illogical things I have heard in this thread. That battery, no matter which battery, will NOT last long.

[ALPINE408]

If he thinks his idea is so great let him do it

But if you think your the only one to think of this or test and found to bbe ineffecent you would be wrong

[HHR Ed]

Isolators cost money too, and the big 3 helps the alternator charge more effectively so you would still need to do that. And 4awg is not large enough for 130A to run to the back.

at 12ft, 4awg is good for 100A, at 14ft it is good for 80A.

There is no cheap alternative to properly charging batteries. Skimping out reduces performance and reliability.

There is a good solution that Mechman has utilized, using 2awg wire for adding a 2nd batt. At 14ft, 0awg is good for about 200A and 2awg is good for about 160-170A.

Now here's something you may not know. Wire increases resistance and reduces in current capacity the warmer it gets. And the smaller it is, the quicker it warms up.

So, if you use wire right at the limit of your estimated current, it will quickly drop below that capability and severely reduce performance.

Example:

You have a 130A alt and run wire at a gauge and length that make it capable of 130A. You connect this to a 2nd batt and amp.

Now, you play your stereo and put a big drain on that batt and the system has to pull a full 130A from that alt. Once it starts this, the wire heats up just a couple degrees and it's capacity is reduced to 125A. This means that it will heat up more and drop to 115A, this means it will heat up more and drop to 90A, and so on...

So after a few minutes of play, you have only 50A being drawn from the alt and a 2nd batt and amp that is starved for power, so voltage drops, amp goes into protect, and you are left with no sound, and a smoking wire.

You can save on batteries and find fair priced wire, but the things you must do is

Use the proper gauge wire (too large is never a problem)

Use batteries of the same chemistry, i.e. Both AGM or both wet cell. And have the size that fits under the hood, and add the size that can properly power the wattage you want to run in the back, and you can calculate the front battery to supplement this.

Use short runs of wire, and strong connections.

And, Do not try and run a power level outside your means. I mean, if you want to run 5000w and can barely afford the amp itself and no batts or wire, the YOU CANNOT AFFORD TO RUN 5000w.

Take everything into consideration. If your budget gets you to 1500w with just 1 batt and 4awg wire, then that's OK, that's in your means and will run properly, stay with that until you can afford an upgrade. Otherwise, you would be half assing it and spend more money in damaged goods.

[WastedTalent]

I also ment when the car is off you could run it on one battery and start the car on the other battery

But system runs off alternator. Electrical needs run off alternator. Screw the system, leave your lights on overnight with the car off. How's your battery doing then? And that's JUST lights, drawing what? 100 watts max combined? Imagine running 2k+ watts without an alternator running. Kill your battery in I'm sure a matter of 3 hours...tops.

As for what HHR Ed said, so true. If you are trying to run a big system... 5k watts or whatnot, don't get the amp and think you're good. You gotta upgrade everything, buy extras, etc. Think 100% stock electrical usually can get you to around 1200-1500 watts, depending on how good your stock is. So go buy a 5k watt amp for a system? Definitelly gonna require a h/o alt (if not more than 1), plenty of batts, tons of wire, fuses, etc.

The only true cost saving idea? Don't get in car audio. Lol. But if you get in it, truly isn't a "cost saving" idea as it is a very expensive hobby and very bad things can happen costing you even more. If you want to go big and never have small stuff, such as 5k watt system and never starting below... definitely gonna be buying piece by piece until you have ALL the pieces... which can take a very very very long time.