Tapil Posted May 13, 2011 Share Posted May 13, 2011 I have a pretty powerful system in the back 1500W total, not overkill but enough to make even a run to mcdonalds and back fun for everyone Anyways... I want to start using my 500W amp to power the front speakers in my car. But I thought the idea of having a 2nd battery was cool, so i bought the cables and terminals and blah blah - anyways take a look at my set up plans and tell me if you think im doing something wrong (ive never done such a thing before) 0G thick copper wire 30 fuse with in 12 inches of 2nd battery and of course a stable ground/earth wire (duh) Main battery Positive [connected to] Rear Battery Positive. Rear Battery grounded to chas in the back Rear Battery 30Fuse inline fuse placed within 10 inches of rear battery positive Is that right? the front battery will charge the rear and the alternator will recharge the front. Would this put more stress on my alternator? Or would this put less stress on it due to there being more storable power? Or would my alternator feel unchanged so long as both batteries are of good condition? ~thanks for reading Id run a split charge but I read people having severe problems with that and such... Quote Link to comment Share on other sites More sharing options...
eppoh Posted May 13, 2011 Share Posted May 13, 2011 So you are going to run these batteries in series? Why do you want 24 volts/ I think that will fry your alternator and lots of electrics Take a look at this howto: http://www.ehow.com/how_7273962_do-dual-battery-system-vehicle_.html Quote Link to comment Share on other sites More sharing options...
hankosolder2 Posted May 13, 2011 Share Posted May 13, 2011 As described, they are in parallel, not series, so you're good on that count. Quote Link to comment Share on other sites More sharing options...
MilesFox Posted May 13, 2011 Share Posted May 13, 2011 I had an ea81 with 2 batteries. I discovered that if i cut out the jack mount, i could fit a battery there as it would be in an ea81 turbo. I used an ea82 battery cable to make that my main battery, and connected a wire from the pos terminal to the back of the alternator. Then on the original side, i kept the termonals that connected the positive to the fuse links, and the negative to e ody, without the starter cables. This worked for double reserve, but it stressed the alternator and gave voltage spikes. I could have had a weak alt, or weak batterites. You can mount them this way, i would recommend a dual purpose marine/starting battery for this if you run both. Do you need the amps while running, or when the car is off? If you want battery for your stereo when the car is not running, use a battery isolator, and run the starting battery for the car, and use a deep cell marine/rv battery for the amp. The battery isilator will let the 2nd battery charge with the alt when the car is running, but will isolate the starting battery when the car is off, so if you run the deep cell down with the stero, you still have a fresh starting battery. A regular car battery is designed to put out a lot of amps for a short time. It is not designed to run all the way dead, or 'deep cycle' as it will sulfate and ruin the lead plates. The deep cycle battery is designed to put out a lower amperage fro a longer time. This is ideal for your stereo to run when the car is off, and it draws nowhere near as many amps as the starter. If you are worried about your speakers sucking the battery dry when the car is running, dim lights, etc, you will want a bigger alternator. Stock amp is 30 amps. You can fit a 60 amp nissan maxima alt in there since it is the same manufacture. AYou can use an xt6 alt for 90 amps if you swap pulleys. Some folk have converted to 100 amp gmc alternators Quote Link to comment Share on other sites More sharing options...
bheinen74 Posted May 13, 2011 Share Posted May 13, 2011 crazy kids. I had an IASCA car once. the only thing to look forward to is smashed windows and theft. Put the stock stuff back in and no issues for the rest of your life. Quote Link to comment Share on other sites More sharing options...
MilesFox Posted May 13, 2011 Share Posted May 13, 2011 You could do a pretty stealth install using the smuggler's trunk, but you wouldn't want to go bumpin' somewhere you don't want anyone to know what you got. It's up to you to decide which is harder to replace: a stereo and some speakers original subaru glass Regardless, a dual battery setup would be pretty awesome. The car could jumpstart itself Quote Link to comment Share on other sites More sharing options...
rverdoold Posted May 13, 2011 Share Posted May 13, 2011 In the off-road camper we have there are also two batteries. However!!! The main battery is used for the car, running starting ect. and the second for the camper (lights, fridge ect.) But we never want the camper to drain the car battery so starting would be impossible. To arrange that we have put a diode-bridge in between. So first alternator charges the main, then the second. So then it is 1 by 1 and not 2 at the same time. We have a jump cable + dash switch in between (via a relay) to jumpstart from the 2nd battery. In your case you might want to put the amp on the second battery only and have a diode bridge in between preventing your amp runs the main battery empty. Quote Link to comment Share on other sites More sharing options...
Tapil Posted May 13, 2011 Author Share Posted May 13, 2011 (edited) So you are going to run these batteries in series? Why do you want 24 volts/ I think that will fry your alternator and lots of electrics Take a look at this howto: http://www.ehow.com/how_7273962_do-dual-battery-system-vehicle_.html This tut tells me to run the negative all the way to th negative on my 2nd battery that sounds like a voltage drop to me crazy kids. I had an IASCA car once. the only thing to look forward to is smashed windows and theft. Put the stock stuff back in and no issues for the rest of your life. If someone really wants to steal $160 worth of walmart audio.... and smashing my windows wont do them any good as there is no way into the trunk from the cab Maybe ill just relocate my battery then? Im getting a few mixed feelings based on every person I ask if im doing this right. For relocation i would just hack off the ends and splice to a new positive cable and run the positive all the way back to the boot then ground the battery back there I would also ground the now hanging negative wire under the hood so its not just hanging down or nothing Edited May 13, 2011 by Tapil Quote Link to comment Share on other sites More sharing options...
MilesFox Posted May 13, 2011 Share Posted May 13, 2011 what year is your car> if its carbureted 85-87, you can install the 2nd battery under the hood where the FI airbox would be. You willneed to make a little shelf for it, though, and cut off the part that holds the ac dryer and the charcoal canister. Quote Link to comment Share on other sites More sharing options...
Tapil Posted May 14, 2011 Author Share Posted May 14, 2011 what year is your car> if its carbureted 85-87, you can install the 2nd battery under the hood where the FI airbox would be. You willneed to make a little shelf for it, though, and cut off the part that holds the ac dryer and the charcoal canister. It is a 97 impreza brighton coupe Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 14, 2011 Share Posted May 14, 2011 Is that right? the front battery will charge the rear and the alternator will recharge the front. Would this put more stress on my alternator? Or would this put less stress on it due to there being more storable power? Or would my alternator feel unchanged so long as both batteries are of good condition? Id run a split charge but I read people having severe problems with that and such... The alternator has to support the charging for both batteries at the same time. It basically sees just one battery as they are in parallel with each other. Ideally they should be the same. There will be more load on the alternator to support the other battery. You should have a heavy duty alternator to do this. If the one you have working now gives out then you should install a larger capacity alternator. Quote Link to comment Share on other sites More sharing options...
Scoobywagon Posted May 15, 2011 Share Posted May 15, 2011 OK...if you're only going to run a 30 amp fuse, why in the world are you pulling 0-gage wire through the car??? That said, you should also understand that there is nothing that wal-mart sells that will reliably produce the power advertised on the box. At that price point, it just isn't going to happen. Just know that. Since you're going to be running multiple amps in this system at some point, here are my recommendations. 1) Run a high-quality 4-gage wire from the positive terminal on the front battery through the car to an input port on a 1-to-4 power distribution block. This wire should be protected with a fuse holder not more than 12 inches from the front battery. Install the rear battery in the rear of the car and run another high-quality 4-gage cable from the positive terminal of this battery to another input port on your distribution block. The second battery should also be protected with a fuse holder not more than 12 inches from the battery. 2) For high-quality power wire, don't bother with the stuff you find at car stereo shops. That stuff is stupidly expensive and is also garbage. Instead, go to a local welding supply shop and as for some #4 welding lead. It isn't pretty, but it is MUCH nicer wire. It is built with thinner strands and more of them. That makes it VERY flexible and helps it cope with the harshness and vibration inherent in an automotive environment. 3) Have each amp draw current on its own output port at the distribution block. This allows you to individually fuse each amp which gives you better overall protection and makes diagnostics easier later. 4) You can run a ground all the way back to the front battery from the rear if you like. It will not really gain you much and it doubles up your wire-pulling workload. Instead, ground the rear battery to the body and make certain that the front battery's body ground is in good shape. Running a new body ground on the front battery with some of your leftover 4-gage isn't a bad idea. 5) If you feel like being a total perfectionist on this install, run your power down one side of the car, signal down the middle and speaker down the other side. Ideally, this will give you a fair degree of separation between high-current DC (your power lead), low current AC (RCAs) and high-current AC (speakers) to avoid any crosstalk, inductance or any of that other fun stuff. Don't feel like tearing the whole interior out of the car to do that? No problem. You can run it all down one side of the car if you like. It really doesn't make any appreciable difference. 6) Some people want to re-wire the speakers on the assumption that the OE wiring isn't up to snuff for the amp they are installing. This might be true in a competitive vehicle, but is patently untrue in a daily driver. Just because someone installs an amp that CAN give you 125 watts per channel RMS, doesn't mean you're ever going to get that out of it. That's because your ears will start bleeding LONG before the wiring becomes a problem. So save yourself a bunch of work and busted knuckles. Don't bother replacing all the OE wiring unless you just really want to. 7) Don't bother with the stupid expensive RCAs. They're just that. Stupid and expensive. Just get a good quality set and be done with it. Good luck with your system! Quote Link to comment Share on other sites More sharing options...
Olnick Posted May 15, 2011 Share Posted May 15, 2011 Very nice writeup Scoobywagon. I'm very impressed with your knowledge. Thanks! Quote Link to comment Share on other sites More sharing options...
AK_Kev_007 Posted May 16, 2011 Share Posted May 16, 2011 (edited) I agree with everything Scoobywagon has said but I have a tid-bit to add. If you do run all the wires down one side you should get two faraid nodes. Faraid nodes are, in most cases, round magnets that you should loop the RCA cable through near both ends. Loop the RCA cable through a node behind the deck and once more at the first amp or RCA splitter of you are going that route. Your computer monitor data cable uses a faraid node covered in plastic and in some cases its on either end of the cable. It is great for cleaning garbage signal out of a 12 foot RCA or any data cable. PM if you need more info. 3 year robotic club head builder/engineer:banana: PS. If your still getting light dimming get a capacitor. Some people don't believe they work but my 93' Impreza would beg to differ. I put it right between the battery and power distrabution/main fuse panel and it even started better!! 1 Faraid per 1,000 Watts rms not peak Edited May 16, 2011 by AK_Kev_007 Quote Link to comment Share on other sites More sharing options...
Cougar Posted May 16, 2011 Share Posted May 16, 2011 Your computer monitor data cable uses a faraid node covered in plastic I think you mean ferrite core. It's not really a magnet but it does suppress various frequencies, depending upon the mixture of the ferrite material. http://www.google.com/products/catalog?q=ferrite+core&rls=com.microsoft:en-us:IE-SearchBox&oe=UTF-8&rlz=1I7GGLL_en&um=1&ie=UTF-8&tbm=shop&cid=761843538070174409&sa=X&ei=FNjQTZz2PJK6sQPHttSSDg&ved=0CEIQ8wIwAg&biw=802&bih=542# Quote Link to comment Share on other sites More sharing options...
AK_Kev_007 Posted May 16, 2011 Share Posted May 16, 2011 I think you mean ferrite core. It's not really a magnet but it does suppress various frequencies, depending upon the mixture of the ferrite material. http://www.google.com/products/catalog?q=ferrite+core&rls=com.microsoft:en-us:IE-SearchBox&oe=UTF-8&rlz=1I7GGLL_en&um=1&ie=UTF-8&tbm=shop&cid=761843538070174409&sa=X&ei=FNjQTZz2PJK6sQPHttSSDg&ved=0CEIQ8wIwAg&biw=802&bih=542# I ment ferrite node, wasn't sure on the spelling though. In my A+ certification class that's what they were called. They are magnetic. Not very strong but they are. Quote Link to comment Share on other sites More sharing options...
monstaru Posted May 17, 2011 Share Posted May 17, 2011 (edited) crazy kids. I had an IASCA car once. the only thing to look forward to is smashed windows and theft. Put the stock stuff back in and no issues for the rest of your life. how is this helpful?when you stow your stuff properly and don't flaunt it like a ********************* to the wrong people you end up keeping it..... i have a 90 amp battery isloator i would be willing to get rid of if you want to go that route.cheers, b Edited May 17, 2011 by monstaru Quote Link to comment Share on other sites More sharing options...
monstaru Posted May 17, 2011 Share Posted May 17, 2011 The alternator has to support the charging for both batteries at the same time. It basically sees just one battery as they are in parallel with each other. Ideally they should be the same. There will be more load on the alternator to support the other battery. You should have a heavy duty alternator to do this. If the one you have working now gives out then you should install a larger capacity alternator. or install an isolator.......cheers, b Quote Link to comment Share on other sites More sharing options...
WoodsWagon Posted May 19, 2011 Share Posted May 19, 2011 (edited) One important point that a lot of people miss- the alternator is what supplies all the electrical loads in the car while it's running. The battery's only supply power when the system voltage is below 12.6v, so either a huge load that the alternator can't keep up with, or the engine off. Since most of the time your using the stereo is when the car is running, the batteries don't matter. They do some AC noise suppresion, but a capacitor would do the same thing. Once you start the car, you can literally take the battery out and everything will still work as normal and you can drive the car around. This isn't recommended because the unsupressed AC noise can damage the computer, however I've done it a few times to move cars around my property that I didn't have a spare battery for. The only reason for dual batteries is if you're going to use the stereo for long periods with the car shut off. You need to concentrate your efforts on the alternator and the cables (ground and positive) connecting it to the battery, and the battery to your load (the amplifiers). Here's a 140 amp rewound stock case alternator for $180: http://www.maniacelectricmotors.com/13752ho.html Edited May 19, 2011 by WoodsWagon Quote Link to comment Share on other sites More sharing options...
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