QuestionQUESTION: So I bought a yellow top battery the other day and I want my subs to run off that, however, when i made the switch from car battery to yellow top nothing works. i re tested with the car battery and everything works... so what am i doing wrong? do i need to ground my yellow top negative to the chasee?
ANSWER: Hi Joe,
I'm not completely clear on what you're describing; but it sounds like you might be just disconnecting the amp's power wire from the car battery, and connecting it directly to the positive terminal of an Optima battery. Is this correct?
If so, then you'd need to at least connect the amplifier's ground connection to the Optima battery's negative terminal as well--or, as you said, connect the battery's negative terminal to the vehicle chassis. Remember that voltage is always relative--when we say a battery has 12 volts, that means there's a difference of 12 volts between the positive terminal and the negative terminal. A single battery terminal doesn't do any good by itself; it only carries a voltage in relation to the other terminal. The vehicle battery's negative terminal is connected to the chassis, so the positive terminal has a voltage in relation to the car's chassis metal.
I'm not sure why you're trying to run your subs from the separate battery. Keep in mind that your battery will need to be connected into the vehicle's electrical system if you want it to be recharged by the alternator. Can you tell me what the purpose of the yellow-top battery is? Do you plan to use the system with the engine off, or are you trying for more current capacity? In a typical car audio system used for daily music listening, adding a second battery isn't very useful.
Hope this helps!
Brian
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QUESTION: Ok so first off my car battery began dying a few days ago. I'm also installing 1 more sub next weekend. So in the past when I would turn up my music my headlights and interior lights would dim a little when it hit strong. When my car began dying I thought getting a separate battery would work better. What do you thoink? I should have consulted here first..oops :)
thank you brian
ANSWER: Joe,
When you say the car battery's been dying: do you mean, it's not being fully charged when you're driving? Or it's dead after the car's been sitting for a while?
For example: if you can start the car, but you have problems with the electrical systems failing while you're driving; or if the battery is dead shortly after you've been driving for a while, then you may have a problem with your car's alternator. The alternator is responsible for producing all electrical power while the engine is running, and it also re-charges the battery.
On the other hand, if you don't have any problems (except for the minor light dimming) while you're driving, but the battery is dead after the car's been sitting for a few hours, then you may have a bad battery or a parasitic drain on the system. A parasitic drain means that something in the car isn't switching off when you turn the key off, and it's slowly draining the battery. An example might be a bad door switch, so that your dome light doesn't turn off; or a mis-wired amplifier, so that the amp stays on while the car is off.
In either case, an extra battery isn't likely to solve the problem. If your alternator is failing, or if it can't keep up with your audio system's current requirements, then adding a battery only makes the problem worse: the new battery needs to be connected to the charging system also, which increases the load on the alternator. Remember: when the engine is running, power is usually not being drawn from the battery. The alternator is the primary power source, and the battery is just another load on it. The only time any power comes from the battery is when the alternator is overloaded, and the charging system voltage drops to the battery level. When you add a second battery and connect it to the charging system, the same rule applies: the alternator must supply all the vehicle's electrical power, and enough extra to recharge both batteries. If the alternator can't keep up, then power will flow from the batteries; but that's an unstable situation. If the alternator isn't keeping up with the electrical demand, then it can't keep the batteries charged either, and eventually they'll be drained.
The summary is, if your alternator's having trouble keeping one battery charged, then adding a second battery will only make the problem worse. I'd start by having your vehicle's alternator and battery tested. Most shops don't charge very much for this service. If your problem seems to be coming from a parasitic drain, there are ways to find and fix it. But unless you spend a lot of time listening to the audio system with your engine turned off, a second battery won't help you.
Good luck!
Brian
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QUESTION: First off thank you I love this service you guys are great. And I will go check my alternator today and see because that is what seems t be the problem. At first it was just dimming and no problems with the battery dying. Now the car won't start if I don't drive it for 2 or more hours. Also I'm not connecting the second battery to the car battery I am connecting the second battery to the amp and grounding the neg to the chassis. However, now the problem seems to be that I have to manually disconnect the second battery when I leave the car. And I know this is bad but I'm using my jumper cables to ground my battery so its easier to disconnect when I leave my car.
If you can what's my best option after I get my alternator checked out and most likely replaced do you suggest checking my car batt. and maybe getting that replaced..but that will just end in me messing up the alternator again....
Thank you again
Joe
AnswerHi Joe,
Sorry it took me a while to answer this one.
If your battery is losing a charge after resting for a couple hours, then it's very possible that a parasitic drain is the cause. If the alternator check out fine, then you might want to have a parasitic drain test done. This involves disconnecting the negative battery terminal and hooking up an ammeter in series between the negative terminal and the chassis. In this way, you can monitor how much current is being drawn from the battery when the vehicle isn't in use. Any mechanic should be able to perform this test.
A typical automotive battery isn't designed to be fully drained and recharged. If your original battery has been drained a few times, it may need to be replaced even if it isn't very old.
I think the first step in correcting your system's problems is to verify that the factory charging system is working as it should. In the long run, I don't think that a second battery is likely to do you any good. Once you know that the stock battery and alternator are working properly, you can see if you still have a dimming problem, and take steps to correct it. In addition to the alternator and battery, you'll want to look at the factory charging system wires. It might help to install a thicker wire between the battery's negative terminal and the vehicle chassis, between the chassis and the engine block, and/or between the alternator's output terminal and the battery's positive terminal. Also, it's important that all the wire connections at the battery, alternator, and chassis are clean, tight, and free of corrosion.
If you know that the alternator, charging system and wiring is all in good condition, and you're still having problems, then it might be time to think about upgrading the alternator.
Hope this helps!
Brian
