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Discussion Starter #1 (Edited)
How to add a second battery ?

I currently run a lot of electronics equipment (lights, audio, etc.) and need more power. When adding a second battery do I just wire it in parallel with the first batter, like wiring in a capacitor? If not, how do I install a second batter?

Thanks.
 

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Use an isolator. This will maintain correct voltage and allow you to selectively charge both batteries with the alternator output.
 

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Discussion Starter #3 (Edited)
So I do run the 2nd battery in parallel with the circuit... but I add in an isolator? What's an isolator and how do I wire it in? Also, when you say it allows me to selectively charge both batteries, does that mean the battery with the least amount of charge won't automatically recharge more than the other one?

Lots of questions, lol. Thanks again.
 

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Typically the isolator circuit sits between the alternator and the batteries. Different models have different features. You might look at RV and/or camping vehicle stores.
 

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Are you running this equipment while your car is running or while the car is off?

If you're using it with the car running, you're just going to kill your alternator doing this. Now, your alternator will have two batteries to charge as it runs. THis will only put more strain on your alternator and not help your situation much at all. The current strain is going to still be placed on your alt, not on the extra batt.

If you want to just use the extra battery when the car is off, fine - but it's still going to be a strain on the alt unless you use an isolator and selectively charge each battery.

It sounds like what you shoul dbe doing here is upgrading your alternator, not adding an extra battery. Just my opinion and maybe something to consider.
 

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Discussion Starter #6 (Edited)
So everyone who's running more than one battery out there is only using it when the car's off? Is there anyway at all to add in a second battery for use when the car is running and in normal operation? I want a second battery because I am running an aftermarket sound system and many lights, with future plans to add more amplifiers, speakers, woofers, and lights. I currently am running a 1-farad capacitor. As it is, I am making excellent power, no lights dimming and excellent sustain of the bass, but I feel like a second battery would give me limitless ability for the future.
 

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for what you are talking about, what you DEFINITELY want to focus on is a high output alternator.

I jsut got my sub a few weekends ago, so i'm not positive on the exact size, but i think the wrx has like a 90A alternator. Get a high output alternator like 150-200 amps and you will be good to go :)
 

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Just a thought... We have a Perko brand battery isolator/switch in our boat. You can switch between 2 batteries, or use both at the same time. Plus it switches to "off" and has a lock so there's no power at all.

I'm sure it would work for a car but you'd have to find a good place to mount it.
 

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Discussion Starter #10
Thanks. I think it'd be weird having an isolator and having to choose which battery to be charging, I wouldn't know when to switch it or what not, and both at the same time sounds like it would strain the alternator too much, so I think I'm going to go with the alternator upgrade.
 

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Re: Where to get an upgraded alternator?

hamz01 said:
Does anyone know where I can get a good 200A or so alternator? Are alternators car-specific?
you might want to head over to SoundDomain and ask around in the 'Electrial Explanations' forum. imtfox, a moderator over there, is usually extremely helpful. They deal mostly with very high power car installs, so alternator upgrades are a fairly common thing.
 

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Hold on there!!! SD_GR gave sound advice and it was ignored. Before running to the vendor and purchasing a new alternator, you need to make sure you even need one. Most competition vehicles do not have oversized alternators, but a trunk full of batteries. I work at Soundwaves, we're currently in every R&D and Car and Driver mag, for the American Racing Avalanche and have competed and won first place finishes as IASCA and USAC. Test your total drain on the battery before you go further. If you're not exceeding the operational capacity of the alternator, no need to go bigger. You need the ability to store power, and frankly, the only thing the Suby battery is good for is a acidic doorstop or paperweight. Try an optima yellow top battery. You will have to extend the positive end of your wire harness under the hood to hook it up properly, but will work wonders for your car in general. You can pick one up for around $200. If you've got extra $$$, Rockford Fosgate makes a monster of a battery with 950 cold cranking amps. If you purchase that one, please resist the temptation to lick both terminals.
 

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ej20fan said:
Hold on there!!! SD_GR gave sound advice and it was ignored. Before running to the vendor and purchasing a new alternator, you need to make sure you even need one. Most competition vehicles do not have oversized alternators, but a trunk full of batteries. I work at Soundwaves, we're currently in every R&D and Car and Driver mag, for the American Racing Avalanche and have competed and won first place finishes as IASCA and USAC. Test your total drain on the battery before you go further. If you're not exceeding the operational capacity of the alternator, no need to go bigger. You need the ability to store power, and frankly, the only thing the Suby battery is good for is a acidic doorstop or paperweight. Try an optima yellow top battery. You will have to extend the positive end of your wire harness under the hood to hook it up properly, but will work wonders for your car in general. You can pick one up for around $200. If you've got extra $$$, Rockford Fosgate makes a monster of a battery with 950 cold cranking amps. If you purchase that one, please resist the temptation to lick both terminals.
the electrical system of a competition vehicle is quite different from that of a daily driver... try charging a trunk full of batteries on a stock alternator.

Although I do agree with you on getting the charging system tested.
 

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Discussion Starter #15
How can I test the total drain of my battery, and then how do I find out whether or not it exceeds the operational capacity of my alternator?
 

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tad_02Wgn said:
the electrical system of a competition vehicle is quite different from that of a daily driver... try charging a trunk full of batteries on a stock alternator.

Although I do agree with you on getting the charging system tested.
True, we use powersupplies to drive and charge these systems, though many of the vehicles we compete in are still daily drivers. Regardless, the alternator is tested with a multi-meter. Very easy.

The alternator upgrade is really not that necessary. I'm running a pretty big system, RF 5002 and RF4004, with Kove Opulent Components in the front and matching 4" rear, with a T3 sub in a custom box. I have had no problems.

The most important thing to remember when it comes to soundsystems is proper installation. Bad install's make up for more than 90% of the problems we fix at my shop.
 

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ej20fan said:
True, we use powersupplies to drive and charge these systems, though many of the vehicles we compete in are still daily drivers. Regardless, the alternator is tested with a multi-meter. Very easy.

The alternator upgrade is really not that necessary. I'm running a pretty big system, RF 5002 and RF4004, with Kove Opulent Components in the front and matching 4" rear, with a T3 sub in a custom box. I have had no problems.

The most important thing to remember when it comes to soundsystems is proper installation. Bad install's make up for more than 90% of the problems we fix at my shop.
I certainly agree with you about the bad installs - most of the dimming problems that I have encountered were usually just the case of a poor ground.

Really when it comes down to it - extra batteries are good for two things.
1.) Extended play-time when the car is off
2.) Providing the extra current necessary for shorter periods of time, much like the reasoning for adding a capacitor.

So... if you're only going to be burping your system, or if your system doesn't draw more current than your alternator - car draw, you're all set.

However, if you are consistently running enough electronics that you are drawing, say, 50A worth of accessories from a 75A alternator... there's no way to get around an upgrade.

It's certainly not somethign to jump into though - it's a big step. Ultimately, however, it is the proper solution to the power problem, instead of just a band-aid type solution like a cap (or battery in some cases).

Not trying to start an argument - I think we're both right and making good points. Situations like this really must be evaluated on a case-by-cases basis.

For example, I ran a 1500W+ RMS system (two ARC Audio amplifiers) in my jetta with the stock 90A alternator without any problems whatsoever.
 

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Which Arc's, KAR or XXK. I'm a dealer and those amps kick. Love them. I'd compare them to the old PPI's.

Anyway, true that on your advice. I like that this thread is actually covering important ground and giving sound advice rather than turn into a pissing match.

I honestly don't believe that you should need either extra battery or alternator, as I'm doing fine. I have upgraded my front battery to a Optima yellow top though, but other than that, I've had no problems, nor required the need to upgrade any other electrical component of my car.

Check your install again, and you will most likely find the culprit.
 

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ej20fan said:
Which Arc's, KAR or XXK. I'm a dealer and those amps kick. Love them. I'd compare them to the old PPI's.

Anyway, true that on your advice. I like that this thread is actually covering important ground and giving sound advice rather than turn into a pissing match.

I honestly don't believe that you should need either extra battery or alternator, as I'm doing fine. I have upgraded my front battery to a Optima yellow top though, but other than that, I've had no problems, nor required the need to upgrade any other electrical component of my car.

Check your install again, and you will most likely find the culprit.
agreed,
I had an arx cxl 4150 and cxcl 1500.. powering focal 165k2 comp set and ed 12a. It was such a nice setup, but i needed money for school and a new car. killer equipment, just way tooo costly.
 

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NICE!!!
 
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