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KYOTE

Dual Alternator Questions

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Before i start, i want to say that i know this question has been asked a million times. Every post i found was a slightly different situation and not the outcome im looking for. 

Heres the setup, i have a 2000 ford ranger 2.5l l4. I have already upgraded the stock alternator to a 320 amp mechman. I bought the exact same alternator for the dual rig. Im going to have to make a bracket for the second alt, as they dont sell a kit. I know i could just get rid of the A/C, but i want it to cool off the amps. Ill take the time to fit the second alternator were i can. Thats a tottaly seperate issue in and of itself.  

Im gonna have 4600 watts of total speaker power. Before i get all of you telling me to just rock a bigger/multiple batterys, please know that im aware of this. If i wanted to, i could just charge the batterys after every bump session and work with the one alt. If you do the math, 4600 watts of output at 14.4 volts comes out to almost 400 amps (factoring in efficiency loss). The 2 alts together at idle will produce 400 amps. I want to be able to bump all day everyday, at stop lights, parked in the parking lot, and not have to worry about dipping below 14.4 volts, or over stressing a single alternator.

To aid this problem even further, im going to get 2 Optima  yellow top batterys and mount them in the back of the truck right behind the sub box. So in total, 2 320 amp alts, with a standard wet cell starting battery in the front, along with 2 deep cycle agm batterys in the back.

Now, i dont know the best way/safest way to wire the 2 alternators to these 3 batterys. I was originally just gonna splice the 2 wires going to each voltage regulator that way they both get the same signal. Then i would run the power wires for both alternators directly to the front battery. The front battery is connected to a power block inside the cab, which will be connected to the back 2 batterys as well.(see attached picture) I decided this plan might not be the best, as the back batterys might not get enough amps to stay charged.

So then i thought to myself, why not run the second alternator directly to the battery bank in the back of the car. It would ensure that the back batterys stay charged. Then i started reading into this and i see people talking about isolators, and how using different batterys will kill the weaker one, etc. 

My main quesiton out of all of this is does it even matter? If i run both alternators to the front battery, will the rear batterys stay charged? Does anyone else have experience doing this? If it is ideal to run the second alternator directly to the back batterys, is there anything i need to know and do to ensure that i dont cook a battery. Do i need an isolator? I want to keep all 3 batterys in the same loop so i shouldn't need one right? Is there a specific way i need to wire the exciter wire, and the voltage wire that way the regulators do there job? Answers to these questions would be super helpful.

 

A couple of side notes: i have attached 2 photos. One is a drawling of my setup and how i plan on wiring the alternators and batterys. The other photo is of a wiring diagram i found on a plow truck website. I was curious if anyone on here has done a dual alt setup the way its done in the diagram. Also, i have breakers on every power wire and have been very careful about making sure everything is protected properly. Im also using 1/0 gauge wires for everything. I have a chart for wire sizing and im well over what i need. Im going over kill on everything to ensure i have a solid wire setup. I have done the big 3 as well. 

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Welp. I'm gonna be that guy. With that power,  I'd run your mechman and some reserve and be done. Your not gonna pull a constant 400 amps. Especially on music. One alt and a couple batteries and you will be more than fine. When you get into making your own dual bracket, fighting belt alignment and proper belt wrap, all those head aches, for a alt, that isnt really needed,... I'd just run one with some reserve. 

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On 7/26/2019 at 6:39 AM, Kyblack76 said:

Welp. I'm gonna be that guy. With that power,  I'd run your mechman and some reserve and be done. Your not gonna pull a constant 400 amps. Especially on music. One alt and a couple batteries and you will be more than fine. When you get into making your own dual bracket, fighting belt alignment and proper belt wrap, all those head aches, for a alt, that isnt really needed,... I'd just run one with some reserve. 

Hey buddy, i really appreciate the reply. I was doing some more math and you are correct. I wont be pulling 400 amps all the time. In fact, ill probably never pull that many amps. The common trend in the car audio arena seems to always be more batterys. My thought has always been more alternators. I think 2 is a practical max before your belt is gonna start tearing from the stress. Id rather have 2 alternators and 1 battery, then 2 batterys and 1 alt. The cost is about the same to. 1 xs power 3400 is $390. The mechman alternator i got was $499. 

Anyway, my point is that im still gonna install the second alternator, but ive changed my mind on the batterys. Im just gonna get 1 xs 3400 as it will fit in my front slot. It says it can handle up to 4000W, and with the alternators, it wont have to make up for much. With this plan, theres no weird wiring and i dont have to worry about keeping a battery bank charged.

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