how to run a 2nd bat.

[mutt_hollon 10+ year member]

Ok i have a few questions, i am wanting to run a 2nd bat. how do i run this exactly. i know i run a 1/0 from the positive on the bat under the hood to the positive on the 2nd one. but do just ground the neg. on the second bat. like i would ground an amp or what.

Also i have the big 3 done, and a cap (i know i should take it off, when i got it i was totaly new to car audio) but i only have a MA Audio amp. its 1600 peak but i got it bridged going to one L7. my lights dim and my volts still drop in the 11.8 when it hit hard....how can i fix this.....

I did not think MA got their true watts unless i had a 17v electric system....i am so confused....can anyone help me..........should i take the cap off..i just made a new box and i ordered a Kollosis 4 guage wireing kit that just came in. i plan on re-wring it on the 23rd when i go home to see my folks.....dad has a full building where i only have a parking lot....lol anyway thanks for any help

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[mutt_hollon 10+ year member]

anyone ??????????????

 

[Ford302Redneck 10+ year member]

A wire from the postive to the postive in the back. A wire from the negative to the negative in the back. You could just run a postive and run the negative to a good grounding point, and use the body as the wire. But I sugguest 1 run of each.

 

[lincolnls 10+ year member]

if you are running a second battery in the rear you are going to need more then 4 gugae wire.

option 1)

you should run atleast 1 0guage + and 1 )guage - fromt he front battery to the rear battery, i ran 4 runs total of 0guage to the rear, the idea is to get resistance down as much as possible.

option 2)

same as above but add a relay on the positive.

this is so that when the car is off (engine not running) and you play your stereo you could run the battery dead but when you go to start your car it will as the stereo was only running on 1 battery

as far as the ground is considered you can run a ground from the rear battery to ground in that back, it will work.

ground the battery in the rear has its down falls thou, for one ideally you want all your car gear to be grounded at the same point to prevent a ground loop. another one is that you can lower resistance on the - though a pair of 0guage then you would if you just chasis ground the battery

bottom line is use atleast 1 0 guage run of + and 1 0 gugae run of -

 

[mutt_hollon 10+ year member]

do you guys think i even need a second bat.

 

[brendan_121212]

Ground the battery right to the frame of your vehicle. If you upgraded the Big three and your lights still dim:

a.) you need a H.O. alternator

b.) something isn't wired right.

Also the capacitor does very little or nothing so it's pointless.

In terms of adding a second battery it prolly won't do much to help you out, IMO. Batteries only hold power, they do not produce it like a alternator does. If your power system is at a deficit (because your alternator isn't producing enough power), all the battery will do is pick up the slack, but only until it has no more power left.

 

[mutt_hollon 10+ year member]

so would taking my cap off help or does that matter....my lights dont really dim, my cap shows that it drops into the 11.8 range and im worried that it will hurt my truck....

what would you guys do....im about to get an amp for my mids soon too...but i think its only like 60x4 RMS......

so all in all...shouuld i remove my cap and see how it does....or try to get a H.O. alt

 

[audiolife 5,000+ posts]

http://www.kinetikaudio.com/manuals/khccells.pdf page 9 i do believe

 

[lincolnls 10+ year member]

the most use for a cap is to filter out AC ripple from the alternator from enterring the amp

 

[helotaxi 5,000+ posts]

the most use for a cap is to filter out AC ripple from the alternator from enterring the amp

There are places for a cap. The typical noobs system isn't the place. A cap can help with small voltage dips during transients. For long droning notes it's worthless unless you have the HO alt to go with it.

lincolnls- I didn't understand your first post either.

Adding a second battery can help with voltage dips and prevent light dimming all together. Batteries don't make power they store it true, but they store a LOT of it. If you decrease the resistance between the storage unit and the thing drawing the current the voltage loss between the two is minimized. The battery in the back also keeps the amps from trying to draw power during transients from the front battery and alt because the resistance in that current path is higher than the one from the rear battery. That keeps the voltage from dropping to the headlights and thus prevents dimming.

Easiest way to add second battery is to simply run a wire (bigger is better) from the + on the front battery to the rear one. Fuse this wire next to both batteries. You can ground this either in the trunk or run a return line back to the front battery. If you have a high draw system, grounding back to the front battery with a large cable is probably a good insurance policy. The idea is to minimize resistance throughout the electrical system.

If you have a system that draws a lot of juice all the time, going with a HO alt might be necessary, but really for the average system that is used to play music and the only times of high current draw are during music transients, the big 3 and an extra battery with adequate wiring is usually going to get the bases covered. In fact if transient dimming of the headlights is what you are seeing (volts dip when the bass hits but returns fairly quickly to normal) a HO alt probably will be a waste of money. The alt can't respond instantly to increased current demand and as such won't help fix the problem.

 

[Thnking 10+ year member]

The alternator has a reaction rate of more than we can perceive. It's not the reaction oif the alternator that causes dimming, it's the cycling of the field once the current draw reaches the capacity of the full field. You avoid this cycling by increasing alternator size.

Mutt: 11.8V isn't going to damage anything. Under voltage for amps isn't typically a problem, as most amplifiers have protection circuitry for this, and voltage has to be really low (under 10V for this to even be considered)

The fact is that an extra battery is only going to give you more juice under 12V...probably it isn't going to have any significant ampacity until the voltage reaches around 11V.

Your best bet is to make sure the (+) and (-) wires in your car including the wire from battery to amps are sufficient size. After that, HO alternator. If your system ever becomes a 10KW system, you'll start needing extra batteries.

 

[PESteele 10+ year member]

On my system i get voltage dips to a around 11.5 on songs like "bass i love you" that have alot of bass. Right now i have the big 3 to one of the 2 stock batteries. Do you think i could lessen my dimming if i replace both the batteries w/ yellow tops and ran the big 3 to the other battery also

 

[PESteele 10+ year member]

bump

 

[yacob.naif 10+ year member]

depends on the batteries you're replacing...........

yellow tops don't have the best output for their size out there, the cells are just hard to kill

how old are your batteries? maybe they're just on their way out?

 

[helotaxi 5,000+ posts]

The alternator has a reaction rate of more than we can perceive. It's not the reaction oif the alternator that causes dimming, it's the cycling of the field once the current draw reaches the capacity of the full field. You avoid this cycling by increasing alternator size.

It isn't nearly that simple. I could put the biggest alt made in my car and I would still get dimming. My factory alt is 165A but I still get dimming. The alt itself could theorectically react instantly but the voltage regulator has a voltage threshold that must be reached before it causes the alt to react. In some cases, the voltage regulator won't do anything unless the voltage dip is of a certain duration (measured in seconds in the case of my car) as it is part of the ECU and will up the engine idle RPM before upping the output of the alt.

The fact is that an extra battery is only going to give you more juice under 12V...probably it isn't going to have any significant ampacity until the voltage reaches around 11V.

A battery has a skin voltage that is higher than its nominal voltage, basically the same as the charging voltage. It will begin to contibute current as soon as the voltage begins to drop. Consider also that having a battery near the amps will also eliminate the voltage drop caused by the cable run from the front of the car to the rear and the gain from adding one should become more apparent.

Your best bet is to make sure the (+) and (-) wires in your car including the wire from battery to amps are sufficient size. After that, HO alternator. If your system ever becomes a 10KW system, you'll start needing extra batteries.

The determining factor on whether or not you need a HO alt is the average current drain of the system. With most daily systems and music the average draw is actually really low (