[3456]

I have a 94 XJ sport w/ a 1200 watt sound system and as of right now, 2 hella 500s with 100 watt bulbs...now the lights dim a bit when the bass hits hard, or the hellas are on, the battery gets drained a bit, i actually i had to replace my last battery. Im planning on gettin a light bar and 4 100 watt lights on the roof, how would i go about putting in a 2nd battery, or would i need to get a new alternator too? im a little confused with the electrical stuff

any help at all would be appreciated, thanks a lot.

 

[stump_breaker]

Well first of all you need to break down and spend the $125 on a Fosgate Cap. If your lights are dimming then your system is pulling more than your Jeep can put out on the peak bass hits which means your amp might be getting 10 to 11 volts at best if not less. It really needs to be at 13 to 14 (depending on the amp - some require more) for maximum punch and efficency and a cap will stay charged up to provide the maximum current needed when it's demanded the most. BTW - CAP is short for capacitor. It's the way a camera flash works . It stores power then dumps it all at once when it's demanded. Do a Google search on adding a second battery and you will find a lot of info and yes, you will need a bigger alternator. Actually, if you add a 140 amp alternator to what you have now that should solve your battery draining problem. And as always, upgrade all your main wires.

 

[3181]

I completely agree with Stump Breaker regarding the power stiffening capacitor. These capacitors are generally in the 1 farad range and a good one will run you a little over $100 bucks.

While this will appear to solve your problem, i think it will only mask the real issue. What I recommed you do is save up about $350 and do the following:

1. Get a good 1 farad cap as aforementioned
2. Upgrade to a 136-140 amp alternator. You could drop a wad on a "Mean Green" alternator or you could go junkin and pull an OEM 136 amp alternator(OEM PN:56027913) that was used in SOME 1997-1998 Dodge B.Series Van, 1997-1998 Dodge Dakotas, 1998 Dodge Durangos, 1997-1998 Dodge Ram Pickups, 1997-1998 Jeep Grand Cherokees. (if you want more info on this simple swap pm me)
3. Get a deep cycle optima. While this may not be absolutely necessary, I feel that with the power you want to draw, this is the RIGHT way to do it.

I figure the cap and the battery will run about $300 and then if you do the 136amp alternator swap for less than another $50 you're set. I beleive that these three upgrades will set you up nicely to run good power to your speaks while running offroad lights.

let us know if you go anywhere with this.

-jm

 

[krabysniper]

I concur on the OPTIMA , I have 2 myself. The absolute best battery money can buy IMO.

 

[Enjoyinglife121]

I concure with everyone else. I'm running duo Optima's upgraded cables, Wrangler isolator and a Mean Green alt.

The only thing I'd do differently, was the alt. With all the other upgrades, the extra capicity of the alt hasn't been needed.

Kent

 

[stump_breaker]

Dang! With all that juice I'm suprised you havn't hooked up 6 or 8 lights or a welder or a small town or something.

 

[3456]

wow, thats sounds pretty sweet, about how much u think all that together would cost, and how did u set it all up, i just want to be able to run 6 100watt lights, the system comes 2nd. But, with that set up, it wouldnt be tough to run everything at,once would it? sorry again, im not good with the electrical aspects of jeepin, thanks again

 

[Enjoyinglife121]

Stump,
Actually I am running a total of 6 sets of light (3 front, 2 rear, 1 under carriage). I also designed the system for a portable welder, but haven't made my mind up on a the welder yet.

I had very minor engine block grinding to fit the alt.

73's
Kent

 

[Enjoyinglife121]

I'd guess total cost of parts was around $660. That would consist of: Pull the alt of the mix and it's almost half this.

$300 Mean Green Alt
$150 Wrangler Northwest battery isolater
$100 2nd Optima yellow top battery
$30 Second battery tray (custom made)
$30 Rusty's cone air filter
$50 wire supplies
25 feet 1/0 gauge red/back cables
4 military connectors
About a dozen connectors with soldering pellets
Couple feet of shrink tape

In order to fit the second battery, I had to pull the stock air box. That's why I included Rusty's airfilter in the cost. The job was a bit time consuming, but fairly straight forward. The wiring for the isolator was probably the biggest pain. Most of that was running and mounting the switch into the console.

I finally got a digital camera, so I snap some photos to add here if you like.

Hope this helps,
Kent

 

[3456]

if i were to just get a bigger alt. and upgrade the wires, and maybe a new battery, do u think i could get away with that, instead of adding a 2nd battery?

and if i could do this, how many amps would you recomend, minimum? thanks

 

[3181]

While a second battery is always great... you dont need it (imho). Also, I dont feel that upgrading wires are going to do anything besides drain your wallet. Again, alternator, capacitor for your sound system, and an optima battery. If your still having problems after that, which you wont, then start looking into these other options.

Again, just what i would do. As you can see, everyone has a different opinion.

-jm

 

[3456]

now, if i am to get a new alternator, would it have to be one of the mean greens? or could i go for a smaller one than that? what would be the minimum amps to power all this?
again, im pretty clueless when it comes to this electrical stuff...thanks again

 

[Enjoyinglife121]

I tend to agree with HTeK. As long as you have a good primary battery, a secondary probably won't give you much (if any) bang-for-the-buck.

The second battery will simply increase your overall reserve capacity when the engine is off. So, unless you plan to run your stereo for long periods of time with the engine off, I don't think it's going to help much.

I also doubt you need a Mean Green alternator. I would think any high output alt would give you the added amps you may need. Here's an alternator break down by rated amps. If anyone notices mistakes below, please post a correction.

Stock OE alt - 90 amps
Most high output alts - 124 amps
Mean Green alts for the XJ - 200 amps

Note: These ratings are maximum rating at a given RPM. At idle most alternators put out much less. For example, I believe the OE alt puts out around 75 amps at idle.

Mean Green used to make a "continuous duty" alternator which put out the same amps across the RPM range. So, at idle it put out the same amps as at any other RPM. I don't know if this is still the case?

Hope this helps,
Kent

 

[2490]

Hit a couple audio forums and websites. Many of them will give you calculators to figure out what you need to be running on the electrical system.

However. The MOST bang for your buck would be a second battery. Assuming you can fab up the mounting.

The battery is not as good as a CAP, but it does the same job (essentially). It can't dump the current as quickly or as much, but it will work.

I COULD be wrong, but I BELIEVE the alternator on my 99 4.0 was a 120 amp. I THINK!

As well I THINK that once the cap or second battery is charged, the stock alternator will hold up fine. But if you continue to crank the sound/lights you are only delaying the inevitable. The batteries will give you more reserve power and more immediately avaliable power, but if you are actually discharging a battery while the Jeep is running, you need to generate more power. Period.

As well I believe the Optima batteries are also beneficial as they are designed to push more current than a generic will.

As a fellow Jeeper and audio guy.. this is what I would do were I on your budget.

In order:

Buy a second battery and fab up a bracket yourself.

Buy a cap.

Buy a larger alternator.

Put in a V8. Won't help the charging issue.. it's just cool.

But don't skimp on wire. Any oxygen free wire is pretty much as good as any other wire. The only real difference between Pheonix Gold's wire and the wire running to your welder is the name on the side and about $4 a foot for the Pheonix brand.

Just buy a nice oxy free COPPER wire and good connectors. For the battery/cap, there is no such thing as going too big.

 

[Guest]

hey there,

definitely start with the cap. if you still have dimming issues look at an alternator, then if you still have issues, look at a 2nd battery config, one that allows both battieries to run in series, its no good to switch from battery to battery because that doesnt really eliminate your problem. you need to have more available amps to draw on, which cannot happen unless both batteries are providing power, this can usually be done from a solenoid, controllable from the dash. switch between either battery or connect both at the same time. this allows you to switch to any setup and allows a battery to remain isolated in case you drain too much power on one. then you can switch to the dead battery after you get started and recharge. i agree with previous replies in that you probably only need a cap and a new alt, dont go mean green unless you want to power lights and stereo at same time for extened periods. the alternator should provide power for all systems unless you are drawing more than the alt can produce, which will suck off the battery, then you will have a drain issue and risk having dead or low batteries. One way to avoid is shut your stereo down at least 5 minutes before you kill the engine so your alternator can do its job and recharge the system.

hope that helps.

p.s. also have your amp wired using at least 10 gauge power lead, this will cut down on power loss contributed to resistance. general rule of thumb is the longer the lead the bigger the wire. (smaller the gauge) make sure you are using the remote on switch connected to your amp to your headset. if not you might be running with the amp on all the time whether or not you have the stereo on or not, this will rob you of some avail power and can contribute to your light issues.

riehl8

in a nutshell

1- cap
2- new alt
3- battery
4- dual battery (in series)

good luck

 

[1572]

In reply to:

Put in a V8. Won't help the charging issue.. it's just cool.

[/ QUOTE ]

i completely agree, with dual altenators like im gonna do

 

[Guest]

Dual alternators????

 

[1572]

yep, no more need for a smog pump so EVENTUALY ill be putting another alt in its spot

 

[Guest]

you will be able to power anything!!

 

[1572]

i want to light atleast 15 feet 360 degrees around my jeep plus winch plus air compressor so ill need it