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[VT-VX] How To Increase Alternator Output Voltage

immortality

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A little mod I've been planning to do for years but never go around too.....

Required parts:
Diode 1N4007 or similar
some wire
Crimp connectors
Heat shrink tubing
Solder
Time
Cold snacks.....

Purpose.

To increase alternator output voltage above normal. A diode has a .6 volt drop across it when power is applied. By adding this to the battery voltage sensing wire the alternator will see .6 volts less then actual and increase the output by the same amount to compensate.

How....

1. Solder a bit of wire to each end of the diode.
2. Heat shrink over the diode (remember the polarity).
0-02-07-2a773d0c3459ef28b47b54c532f1b43030e59cec5cb393debd8d84d41217af02_c06d4948.jpg

3. Add crimp terminals to each end ( and mark one end for polarity)
0-02-07-d8faf274de4974d5924f8469d6194937324a0a67c1e9e2cdc11d833ad20446e6_dda23734.jpg

4. Install on vehicle.
0-02-07-cbf77ed7450dfa4a15a5cc5b024af287cadb13b48677b5ba70d1a2ee910eea41_25f7ea30.jpg

I used 8mm crimp lugs, unbolted the original alternator voltage sensing wire and added my diode pig tail into the loom. The diode has a little silver band on one end, this needs to face towards the alternator.

Test. IF you have installed it correctly you should see a .6 volt increase over what you had before. If you installed it incorrectly (wrong polarity on the diode) the battery light will be on and the alternator won't be charging so you will need to turn it around and re-test.

I installed this on a VX but it should work on any car fitted with an alternator that has a voltage sensing wire (VN to VY). VE and onward use a different alternator voltage control system so I have no idea if this would work. On my car the battery voltage (at idle, no load) went from 14.1 to 14.7 volts.


Consume cold snack.

Warning: I make no guarantees that this will work and won't blow up your car. Do this mod at your own risk.
 

Jolls

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@immortality this is neat trick - but I am really interested to know to what end/benefit? Let me try to explain the why - I trust I don't come across as being a dick!

An alternator should output at its maximum rated power above around 2000 RPM or so. Below this RPM, the alternator will output less current (due to lower input power (rpm*torque)). In any case above 2000 rpm it will try to maintain a voltage between 14.0-14.4V.

In the ideal world we would charge a lead acid battery at a 10 hour rate to maintain peak health (this is based on their Amp Hr rating as opposed to the CCA) anything quicker results in damage. eg a 50Ahr battery would charge at 5A. 14V @ 5A = 70W, around an average alternator output; the same 14V at .5A (charged battery) would be about 7A and would result in less load on the motor driving it.

My understanding of the voltage sensor is that it is used to regulate the output of the alternator to provide the "optimum" rate of charge. The application of a higher current/voltage could damage the battery due to overcharging. Now .6V is bugger all and I understand that.

What I don't quite get - and I'm looking to be educated here - is what benefit you get from this mod over the factory design?

Please don't take this as a dig - I am genuinely interested in learning/understanding.
 
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mpower

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i feel like this could do more harm than good, what's the thinking?
 

Pollushon

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Current determines charge rate and is where the danger lies in over charging a battery. Voltage determines current potential. If you're only increasing the voltage and not the current then you will increase the efficiency of the systems that run from the battery by reducing sag. In a vehicle with a hella sound system or a camper of some sort this is a great mod. The average car probably won't benefit much but there's no risk in it.

I'm planning on doing this due to my newly added intercooler and fuel pumps
 

immortality

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^^^^ Nicely put.

As one of my old school teachers used to say when explaining the electrical pixies using a river as an example. voltage is how wide the river is and current is how fast it flows.
 

Jolls

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Current determines charge rate and is where the danger lies in over charging a battery. Voltage determines current potential. If you're only increasing the voltage and not the current then you will increase the efficiency of the systems that run from the battery by reducing sag. In a vehicle with a hella sound system or a camper of some sort this is a great mod. The average car probably won't benefit much but there's no risk in it.

I'm planning on doing this due to my newly added intercooler and fuel pumps
I sort of follow you but power is limited (P=VI); so if the total output of the alternator is 65A you only have that to play with. More voltage = less current. The output of the alternator doesn't change so how does this give you more to play with in relation to a camper trailer, lights etc? In my mind the issue is current; as the voltage in a parallel system is the same. The current is what is distributed between the loads. If you add more load surely the only logical answer is to add a larger alternator to provide the required additional power.

Perhaps sag is the missing link here - can you elaborate?

Or am I missing something?
 
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shane_3800

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Good mod thanks for that.
 
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immortality

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07GTS

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depends on some components also as the VE charging system lowers the voltage from 15v to low 14v's once the headlights are on as the globe type dosnt like too high voltage, i also use over run pulley on the alternator if u have ever spun one by hand u know the inertia they have then think of it at 20,000 rpm with your belts trying to control it, o/r pulley takes all the stress off the belt and i also noticed a change in fueling error during deceleration from less load on the engine from it also
 

immortality

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depends on some components also as the VE charging system lowers the voltage from 15v to low 14v's once the headlights are on as the globe type dosnt like too high voltage, i also use over run pulley on the alternator if u have ever spun one by hand u know the inertia they have then think of it at 20,000 rpm with your belts trying to control it, o/r pulley takes all the stress off the belt and i also noticed a change in fueling error during deceleration from less load on the engine from it also
That is one mod I'm looking to do on my alternator too. I've seen the pulleys online but I believe there is a special tool needed to fit them?
 
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