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Does anyone know what the output is on a stock alternator and what have you done if you have upgraded. I have two Optima group 31 yellow top batteries and I need more power.....
 

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Does anyone know what the output is on a stock alternator and what have you done if you have upgraded. I have two Optima group 31 yellow top batteries and I need more power.....
How do you know if you need more "power" if you don't know what the current output is? You just need "more"?? What are you running that has a huge constant draw? Two batteries != anything.
 

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Running a welder? Just a thought...

Would one of Mean Green's work?
 

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The reason I am looking for a higher output alternator is when I run my inverter for a while when the engine is off it or even play the stereo for a long time it can take quite a while to bring the batteries back up to normal. I have a prosine 1.5kw inverter and the batteries are rated at 90 amp hours each. I use a xantrex pathmaker adjustable battery combiner/isolator to tie them together. I don't know what the output for the alternator is but I find it hard to believe it is much more than 100amps. I haven't seen a bolt on replacement so it looks like I will have to go the rewind method.
 

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I was wondering the same thing! I see now why you want more juice... I was thinking about adding a larger inverter for running power tools when I do my second battery install.

How well is your current capacity for running the inverter for extended periods of time? Would it benefit to add another battery and use a battery controller or isolator which allowed for three or more batteries (if your current one doesn't)?

Re-winding the alternator would definitely help your problem with bringing the bank back up, although I'm not sure how much more they could get out from the stock alternator assembly. It's definitely worth a look and I think everyone would be curious to know what the maximum they could do with a stock alternator would be.

I also second VooDude's recommendation of the Mean Green stuff. Might want to give them a call and see if they have anything which would fit the FJ. If you do give them a call, let us know what they say, ok?
 

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X2 with the mean green.. there's another popular manufacture as well, but i can't remember the name. On the Jeep (TJ) we discovered that some parts from Dodge trucks were interchangeable, but with more capacity. Possibly another Toyota product with more output will bolt up.. They probably make commercial vehicles for some markets. Just a thought.. Ron

Does anyone know what the output is on a stock alternator and what have you done if you have upgraded. I have two Optima group 31 yellow top batteries and I need more power.....
 

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The only thing you might want to consider is the recharge rate. Optima lists "unlimited" amps for alternator (13.65 to 15.0V) and rapid recharge (up to 15.6V regulated), but with the exception of 125F max battery temp. So you might want to look at what temp the stock alternator is running your batteries up to, then adjust your alternator upgrade to get near but under the battery temp limit???
 

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What is needed to get a constant 14.4 volts. What do i have to do to my truck/alternator to keep the voltage up? In the morning my scangauge is reading 13.9v, but after a few minutes it drops down to 13.2-13.4 average. Is there a way to trick the truck's electronics to think that i need 14.4v constantly? I changed the battery to a diehard platinum battery. Didn't need to but I'm eventually gonna get a bumper winch setup. I'm sure all the electronics in the truck can handle it. Any suggestions. PM me just incase i don't find this thread. Thanks in advance.:)

OH yea! 14.4 volts for my stereo.
 

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surprisngly enough, when a lead acid goes into currentlimited charge, its voltage drops slightly initially, flattens out, and then rises.
 

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What is needed to get a constant 14.4 volts. What do i have to do to my truck/alternator to keep the voltage up? In the morning my scangauge is reading 13.9v, but after a few minutes it drops down to 13.2-13.4 average. Is there a way to trick the truck's electronics to think that i need 14.4v constantly? I changed the battery to a diehard platinum battery. Didn't need to but I'm eventually gonna get a bumper winch setup. I'm sure all the electronics in the truck can handle it. Any suggestions. PM me just incase i don't find this thread. Thanks in advance.:)

OH yea! 14.4 volts for my stereo.
Why do you want to raise the voltage? I think Jacobs Electronics used to sell a 16 Volt setup including a 16V battery.

DEWFPO
 

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Becareful if having your alternator mofified or changed to something else. I have been working with the owner/engineer of the Mobi-Arc onboard welder to have one of their welders put in my FJ. There han't been a replacement battery that has been made that cleanly installsin the FJ. The engineer called Nipendenzo (sp???), the manufacturer of the alternator, and they told him that the alternator in the FJ is a different style than any other they have built for Toyota. Evidently it talkes to the computer and vise-versa. They are now using it in all their newer vehicles due to its success in the FJ. It is a VERY powerful alternator. It is rated at >120 amps. However, the manufacturer claims it will easily do 140 amps at driving RPMs. The Mobi-Arc engineer and I pretty much gave up on the whole idea of modding the alternator to externalize the regulator for a welder due to the cost associated with the changed that would need to be made.

If you are having charging issues I doubt your alternator is the culprit. If you are running an inverter you should have your truck running or at least start it periodicly to recharge the batteries. If you look at someone like cruiserlarry running all his lights I can pretty accurately say he drawing around 1500 watts which equates to around 125 amps of draw. That wouldn't even include the electronics iside the vehicle or the the stock lighting and electronics. That's just the external lighting he has added to the FJ.

NOTE: I get these numbers (1500 watts) based on what I have put on my FJ and calculting the draw they'll have when I finally get them all wired.
 

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If he was continuously drawing the maximum current, it would be an issue with drawing more than the alternator could continue to push. I think this is what he was saying... Maybe he can chime in and help us understand more.

That being said, this is very interesting information you've come across. I wonder if someone can get direct confirmation from the manufacturer...

I hadn't looked at the charging schematics, but I just took a look in the FJ Electrical PDF. All I see on page 68 (69 of the actual PDF) is the "L" terminal on the alternator going and splitting to the ECU and battery meter. I'd bet all the ECU is doing is monitoring the voltage via that terminal. I don't think there's any special computer connection here, at least nothing that I can see.
 

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from what i've read and heard about power inverters.which are widely used on big trucks. like the one i'm using t the moment to run this puter.they say u need to run the engine to keep the batteried from discharging and going dead.
there is no alternater on the market that i know of that will keep up wth that type of constent draw.sooner or later the battery will discharge.
that is the reasoning behind multiple battery setups....

look at the professional stereo people..they have 3 plus batteries to handle the power draw.

i'm still trying to figure out what he is looking for...when u run the alt at full output u will kill it in a short period of time.....

help me??what r u looking for and y??????
 

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Just curious! It's not only the amperes that I want to bump up but I want to up the voltage too! No more than 14 volts. Just curious, nothing that I was gonna experiment on my own with. Thanks for the replies.
 

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From what I have been told about rewinding the nepindenso alternators is they use a new type of copper winding...the traditional winding is a cylindrical type copper winding...basic copper wire. but the new windings use a square type of winding...some japanese engeneer found that this not only gives the alternator more room but for some reason it is more efficent. so rewinding the newer type of alternator is not possible. I found that if you go with a spiral or gel type battery that it carries the characteristics of a large capacitor, which can handle large load discharge with faster voltage recovery. I have a Kinetic 800 that has 950 amps of power at 200 farrads of capacitance...here is the link
http://www.kinetikaudio.com/default.asp
good luck and if anyone knows of someone who has modded a FJ alternator send me the link please.
 

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Just curious! It's not only the amperes that I want to bump up but I want to up the voltage too! No more than 14 volts. Just curious, nothing that I was gonna experiment on my own with. Thanks for the replies.
If you put a voltmeter on your battery with your FJ running and load on the electrical system, you should see that you are already getting 13.8 volts from your alternator. The regulator in the alternator will not allow more than 13.8V to 14.0V or it would fry the electrical system in your vehicle.
 

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What is needed to get a constant 14.4 volts. What do i have to do to my truck/alternator to keep the voltage up? In the morning my scangauge is reading 13.9v, but after a few minutes it drops down to 13.2-13.4 average. Is there a way to trick the truck's electronics to think that i need 14.4v constantly? I changed the battery to a diehard platinum battery. Didn't need to but I'm eventually gonna get a bumper winch setup. I'm sure all the electronics in the truck can handle it. Any suggestions. PM me just incase i don't find this thread. Thanks in advance.:)

OH yea! 14.4 volts for my stereo.
The voltage will drop as the battery charges and the load on the alternator increases - normal range for an automotive alternator is 13.7-14.5 when working to maintain battery charge and run loads. To keep a constant voltage to an accessory, you might consider adding a voltage stabilizer for the accessory, and leave the alt alone. Jacobs used to make voltage stabilizers with adjustable outputs from 14.4-16.4 volts, but the company was purchased by Mr Gasket, who promptly took their patents and shelved most of their products. Check with high-end stereo shops for a similar item. I'm running lots of electrical components, and have not "overrun" my alt yet, so I'd suggest leaving it alone, too. If you really need a lot of additional amperage, you could mount a second, dedicated alternator for those devices with the regulator set at a higher voltage output w/o affecting anything else in the vehicle - but it may be a trick to mount...
 
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