More times than not, I see people on Youtube with an extra battery in the trunk instead of having a better alternator. Isn't this just pointless? You can hold more juice, but if you can't replenish it faster than you use it, what's the point of 2 batteries?

The only thing I can think of is that it's better because you can charge both batteries when your system isn't playing.

Just for me I always have my bass on when I drive so this seems weird to me.

EDIT: Another thing that gets me. I have 900RMS and my headlights dim, meaning I may have to replace the alternator and battery which costs hundreds.

How do people have 3000RMS and just upgrade their battery?

I feel like for the minor system I have I shouldn't have to spend $500 on car parts to make it work.

Edited July 27, 201213 yr by xxbobbyfinxx

batteries are more used than alts in car audio.

Stock alt should last you quite a long time. If the stock alt burns out and you do not think you were abusing it, then you need either a DC XP alt or no high output alt would suffice.

I have ran 6 3500w amps on stock alt before for several months. I monitor very closely what was going on to ensure the safety of the stock alt. And that was 2 yrs ago. Stock alt still works fine today. I used stock alt because high output alt burned up....

I have an XP alt sitting here to be installed but will do it once my build is complete.

XP alts have temp sensing in them to prevent the rectifier from burning out.

Either running hids so they don't dim or, running a good batt in the back helps tremendously.

Check all grounds too. A lot of times lights dimming can be from a bad ground. What are you running for a system?

Check all grounds too. A lot of times lights dimming can be from a bad ground. What are you running for a system?

I have 2 Kicker CVX 10's @ 900RMS.

While these replies are all great, they don't answer my question. Adding another battery just adds more juice, but the alternator still can't keep up, so doesn't that just prolong the problem?

What size alt do you have? When I added a second battery to the back I didn't notice any problems with the alt at all. It should be able to handle the charge just fine. It also did wonders for keeping my voltage higher.

What size alt do you have? When I added a second battery to the back I didn't notice any problems with the alt at all. It should be able to handle the charge just fine. It also did wonders for keeping my voltage higher.

I think it's the upgraded alternator which is 130 amps.

i gave you a real world scenario...

The more batts you add, the more current that will be supplied from the alt to the batts to keep them maintained...

I would not suggest dumping more than several batts onto a stock alt but you are referring to just one extra.

I do not believe you will be full tilting the stereo every second the car is on....

Therefore, when you are not, the alt will be attempting to charge batts.

In this instance, you would benefit from a remote voltmeter.

Speculation discussions won't get you a definite answer. Time to get some experience yourself as every install is different.

i gave you a real world scenario...

The more batts you add, the more current that will be supplied from the alt to the batts to keep them maintained...

I would not suggest dumping more than several batts onto a stock alt but you are referring to just one extra.

I do not believe you will be full tilting the stereo every second the car is on....

Therefore, when you are not, the alt will be attempting to charge batts.

In this instance, you would benefit from a remote voltmeter.

Speculation discussions won't get you a definite answer. Time to get some experience yourself as every install is different.

If upgrading my main battery is all I need then I'm fine with that. I just don't know how the alternator can charge the battery when I run my bass every second I am driving. I mean the headlights dim which tells you it can't keep up as is, so I always thought another battery would just bandaid the problem.

Also, my ground is a very solid ground, straight to the sheet metal at the bottom of my truck.

Upgrading your front battery to an XS Power or equivalent will help out a lot. Your alt already charges at 14+ volts so adding another battery will be fine for charging to bats.

Upgrading your front battery to an XS Power or equivalent will help out a lot. Your alt already charges at 14+ volts so adding another battery will be fine for charging to bats.

The battery also costed $260 (XS D3400) which I thought was a little ridiculous since my system is pretty small.

I'd do the Big 3 upgrade but frankly buying a battery seems easier than rewiring all that stuff.

I just envy the people who get a 2000RMS system and throw it in their trunk with no problems.

Do the big 3 as well. It's simple to do and will help out a lot. Try the big 3 before you purchase a battery. If it stops the dimming of the headlights then don't worry about upgrading battery.

Do the big 3 as well. It's simple to do and will help out a lot. Try the big 3 before you purchase a battery. If it stops the dimming of the headlights then don't worry about upgrading battery.

Yeah, I just gotta spend the money on 1/0 guage wire and muster up the time to rewire my car.

I'll see what I can do.

I hear you. I hated buying more wire. Even tho I only did it in 4 gauge because that carried more than enough amperage from the alt, which is 130 amps, to the battery. I've got some 0/1 gauge waiting to be thrown in.

I hear you. I hated buying more wire. Even tho I only did it in 4 gauge because that carried more than enough amperage from the alt, which is 130 amps, to the battery. I've got some 0/1 gauge waiting to be thrown in.

How much wire do you think I would need to do the upgrade?

And will 4 guage be enough for me as well or should I just do 1/0 guage anyways?

Yeah, 4 gauge should be enough for you too. 4 gauge should be able to hold around 140amps. I ordered 5 ft of power and then 8ft for ground. I'm not sure where your alt is and the distance to the battery.

I can say first hand how much the big 3 will help. I did it 2 weeks ago, before i did it, my truck would cut off at a redlight if i didnt turn the radio down, my volt meter would actually drop to nothing. and my bright lights would look like dims when the subs hit. Now, after the big three, my lights barely dim at all. even at redlights.

Basic facts are that even HO alts will allow the lights to dim without good battery support. All the alternator needs to do is meet the average current draw of the system. Most people would be surprised at how low that actually is with actual music (i.e. not constant, droning tones). The battery or batteries handle the heavy transient loads (you know, the ones that cause the voltage to drop and the lights to dim) pretty much regardless of the peak capacity of the alternator. The alternator is only producing the amount of current demanded of it at any given time and it takes a finite amount of time for it to ramp up the output. That transition time is when the lights dim.

If you've ever used an air compressor, the compressor itself is there to maintain the pressure in the tank and the tank handles the pressure spikes. If you're running a high constant demand tool (sprayer for example) then the actual compressor matters, but for low average but high peak demand tools (like a nailer) the capacity of the tank is more important. Think of the compressor as the alternator and the tank as the baterries. Music is normally high peak, low average in demand. The batteries are more important in that situation than the alternator. If you are one of those that listens to music with constant, droning bass notes, the average demand is higher and an alternator upgrade (supported by a good battery or two) would be wise.

Regardless of what you do or need (batteries or alternators) without adequate wiring to carry the current none of the rest of it matters. You need adequate wiring size (it is impossible for it to be too big) and solid connections at every terminal distro block and amp. Bad connections will not only make wire size largely irrelevant, but can also be dangerous as the resistance of the bad connection will create very large amounts of heat during high current draw situations. Fuses won't protect from a fire caused be a high resistance connection.

Good answer helotaxi.

You need both, but if I have to choose, I'll do more batts first. You just have to keep an eye on the voltage an allow the batts to replenish as the voltage drops.

I ran the stock alt with 4 batts in my suburban for 2 years with 8000 watts. Did a single 250 amp alt and 9 batts with 17000 watts for another 2 years.

My Astro was a single 250 amp and 15 batteries for 25000 watts. . .

The thing is I don't want to do that much. I only have 900 watts and I feel like I shouldn't have to spend more on car parts that audio equipment.

Most alternators I see are 250amps but only 130amps at 800RPM. That's for people in competitions to do.

Why must I go through all this for 2 10's?

The thing is I don't want to do that much. I only have 900 watts and I feel like I shouldn't have to spend more on car parts that audio equipment.

Most alternators I see are 250amps but only 130amps at 800RPM. That's for people in competitions to do.

Why must I go through all this for 2 10's?

I honestly don't see why is it so difficult for you to grasp such an easy concept. Many respectable members here have given you more than enough information in regards what you should do and why.

If you don't want to spend more on parts than equipment, then buy better equipment. Do some research, and find equipment that is more efficient than what your running now. When it all comes down to it, you either spend a lot of money on equipment, or a lot of money on what to you refer to as "parts". That is the basics for a budget system.

Again, many members here have answered these questions for you. The reason why most competitors use a single Alt, is because, in my situation, to stay in the class I want to run in, the max limit is a single alt, which in turns, is the reason for multiple large batteries. This can be done because in my situation, and with others, you only need 2-3 SECONDS to recieve your score. Now, when you go see other people, who run 10k, 15k, 20k rms, they use multiple alternators, most likely because their goal was to be a daily ground pounder. In this scenerio, there is a constant draw or command from the electrical to keep up with the system. This is where and why you will see 2-6 alts in a single install.

Each system is different, and only calls for certain equipment/parts.

You don't have to go through "all this", to maintain a properly equipped system. As stated before, just do the basics, and don't skimp over anything. The reason you must go through all this is to prevent failure. Thats like, asking why do you have to study in school, when other students never study a day in their life, but yet have all A's. Its a peer to peer basis. In my current system. I run a single Crescendo 5500, 1 stock 130a alt, one battery under hood(from walmart), and one D3100 in the rear. And that is it. But monitoring my voltage is very key. I never drop below 13.5 volts while driving, and nothing below 12.7 while in idle. Yes I have all 1/0 wiriing, multiple powers, and multiple grounds in different locations. But hell, you can get a 1/0 kit off ebay for 30$ nowadays.

I would suggest you to get 10ft of 1/0 to upgrade to the big 3. Charge your current battery over night a parts store (its free), and go from there. Also, buy a volt meter, so that we are no longer playing guessing games of where your voltage is. Its 25$ off ebay, I know, I know, that might be a whole lot of money, but it is important for you to know where your at.

See you're setup is an example of what I want.

I'm sorry, but I don't like being told I need a new alternator and 2 batteries when I have such a simple system.

I like the advice, but I know that people with 900RMS somewhere else in the world don't need a 300$ alternator for their $400 system with 900RMS.

Good advice was the big 3, as that seems reasonable for my setup, an upgraded battery should follow.

But sorry if I'm not ready to buy a new alternator for my barely a setup system.

Thanks for your reply though, you have 5K watts with only simple stuff done to your car. I can manage that.

Also, is yours a daily ground pounder? Could you leave it on balls to the wall while driving?

Is there a single battery I could use for 900RMS under my hood?

What's your Walmart battery capable of?

See you're setup is an example of what I want. I'm sorry, but I don't like being told I need a new alternator and 2 batteries when I have such a simple system. I like the advice, but I know that people with 900RMS somewhere else in the world don't need a 300$ alternator for their $400 system with 900RMS. Good advice was the big 3, as that seems reasonable for my setup, an upgraded battery should follow. But sorry if I'm not ready to buy a new alternator for my barely a setup system. Thanks for your reply though, you have 5K watts with only simple stuff done to your car. I can manage that.

Many people are just giving you "their" advise. You can't/don't want to do that, then don't. But don't get offended by others suggestions either, after all, you are the one who asked.

I wouldn't go by other ppl's system in the world either. Lol. A lot of bad things can happen when following ppl on youtube. 900watts may not seem a lot to you, but you have to remember when that vehicle was designed, it was not design to handle anything else more than the vehicle's needs. So, you can't be pissed at the system, if the manufacture did not design the car for what your trying to do to it.

With 900 watts, your at the max load of running a system with a stock electrical anyway. Most stock vehicles can only handle an additional of 750-1200 watts. This is fact. If you feel the need of more power, but lights are dimming, I would suggest turning down the gain, because light dimming and other symptons will only lead to something failing. This is just a fair warning.