VS alternator upgrade to VT

kinga · #1 28-08-2008, 09:58 PM

I have searched the forums here and have found no definitive answer so please dont ask me to search for this.
Will a VT alternator fit a VS v6, and will it provide more amps. I have heard that a VT provides 100 amps and VS 90 amps, and I have heard that they both provide 85 amps, I am really not sure.
I have a big amp in my VS v6 and am finding the battery is slow to start and am wondering if this is something I should consider, if they are interchangable and willl provide more power.

kopper69 · #2 29-08-2008, 06:03 PM

If you are having problems with the battery or charging system you are better off fixing the problem then worrying about changing a working system.
The only reason you would need to upgrade your alternator would be if you are running accessories that require a fair bit of power or an audio system that really sucks the juice. The factory alternator will provide you with more than enough power to run a stock electrical system with a decent sound system and fog lights, neons etc.

To test the electrical system you need a multimeter. Start by checking the connections. You would be surprised how many times people say yeah yeah connections are fine, and a loose connection ends up being the problem. Double check all power connections starting from the battery. Give the cable a pull and make sure it is rock solid in the connector. Check the bolt that holds the cable on, on the back of the alternator as this is known to work loose over time.

If you have a multimeter you need to measure the voltage of the battery at rest. Preferably after 24 hours without the car being on. Next, check the voltage while you start the car, see what the voltage drops to - you wont get much chance to see this figure so be ready. Next record the voltage while the car is running. Let us know what figures you get from those tests and we can tell you if anything is odd. If your battery is over 3 years old or has had a rough life I would be replacing it.

When you say you find the 'battery slow to start', I assume you mean the engine is slow to start. Is it cranking for a long time? If the car cranks for a while before starting, chances are its nothing to do with the battery. If the battery was dieing the car would struggle to crank.

VT Alternator into VS V6

This thread might be worth reading as its the exact same question. Your alternator only produces as much power as the electrical system needs. So if your electrical system only need 20A, the alternator is only going to put out 20A - it doesnt matter if you have a 60A, 80A, 100A etc etc.

kinga · #3 30-08-2008, 07:55 AM

That thread doesnt answer my question though, which is why I posted this thread, and why I said "PLease dont ask me to search the forum".
I just had a new battery put in, and just replaced the old alternator that was faulty(putting out 13.9 v) with one secondhand (putting out 13.7 volt)
I know a new one should be putting out over 14 volt, but thats also 250 bucks, and I can get a replacement VT one from the wreckers for $80.

Back to my original question, will a VT alternator fit straigh onto a VS, and does it out out 100amp vs 90amp VS. As a VT is newer, a secondhand VT alternator is more likely to be in better condition and put out higher voltage.

PanthaVS · #4 30-08-2008, 11:12 AM

Quote:

Originally Posted by kinga

That thread doesnt answer my question though, which is why I posted this thread, and why I said "PLease dont ask me to search the forum".
I just had a new battery put in, and just replaced the old alternator that was faulty(putting out 13.9 v) with one secondhand (putting out 13.7 volt)
I know a new one should be putting out over 14 volt, but thats also 250 bucks, and I can get a replacement VT one from the wreckers for $80.

Back to my original question, will a VT alternator fit straigh onto a VS, and does it out out 100amp vs 90amp VS. As a VT is newer, a secondhand VT alternator is more likely to be in better condition and put out higher voltage.

If you put any move voltage into your battery from the alternator, you will COOK it! (literally)

Alternators are whats known as a "Constant Voltage" Charge system. ALL alternators from as old as the VB... up to the VE, will put out the same voltage. (Assuming they havent done anything wierd in the newer holdens)

The capacity to put current out is ONLY what you need to concern yourself with.

If you are running a stereo system that is draining the battery (Drive at night and raise the stereo bass... do your headlights dim strongly?)

then you can sort this out with a few tricks...

1. Buy a 1Farad Capacitor and put that into your subwoofer system. (ask a stereo junkie why...)

2. Buy whats called (i think) a "Yellow Cap" battery... (Again, ask a stereo junkie...) they are a sealed battery with a Lower internal resistance that are able to put out higher current loads for short periods of time. (when the Sub woofer beats...)

3. Turn your stereo down... i'd hate to have your hearing when you're 40! Not to mention the harm it does to your body's internals with the constant vibrations!

answering your question:

They "should" fit, but why bother... if youre having the problems you describe... that 10amps difference won't do squat?!

if you INSIST on knowing... ring a commodore wrecker and ask... you got the price from a wrecker... most people who run those places are mechanics... or VERY knowledgable on cars and interchangeability of parts!

VSIIBerlinaL67 · #5 30-08-2008, 02:49 PM

yes it will fit ive done it

hartsc · #6 02-10-2008, 06:49 AM

yea VT v6 ones work fine on VR/VS, I had one on my old v6, all that is needed to change is the front bearing cover 4 screws hold it on, and swap it over and your done, I went from 80amp to 120amp one, never had any wires fry or anything.

DannyboyDS · #7 07-10-2008, 07:47 PM

there is also a good thread in the generalk section I think regarding how long peoples cars take to crank over, can't remember the thread title though

centy · #8 09-10-2008, 06:01 PM

Ok to make thing clear for you.
A car battery is about 13.6v (2.2v per cell)( there is a little variation)
When a battery starts to go flat the voltage drops.
A alternator charges at the same voltage as the battery or JUST above, when the battery voltage rises to the same as the alternator the RESISTANCE goes up so the charge rate drops off till they are equal.
This is why a flat battery will take charge much faster then a nearly charged one, it has a very low voltage.
A alternator producing 13.9v is about right for the voltage of the battery so would not cause overcharging which may lead to the cells boiling and excess production of HYDROGEN GAS.
If i have to explain how bad that idea is then you realy are to silly to drive a commodore.

Personaly i would look at a faulty fuel pump relay for slow starting.

kopper69 · #9 10-10-2008, 07:15 AM

centy, I would say that the car battery is 12V. A fully charged battery at rest will normally sit at around 12.6V (or 2.1V per cell). Your maths is a little off as 2.2V per cell is only 13.2V (6 cells). A 12V battery is normally charged to 2.4V per cell or 14.4V.

The alternator uses a fixed voltage charging system. This is normally set at 14.4Volts. If the alternator was at the same voltage as the battery there would be no potential difference and the battery would not charge at all, the alternator voltage must be higher to charge the battery. It doesnt sit JUST above, it sits (being fixed voltage) at around 14.4V.

The resistance does not increase as the battery is charged. The alternator is a fixed voltage. As the battery is charged the voltage increases, as the voltage increases the potential difference between the alternator and the battery becomes smaller and smaller. Once there is no voltage difference the battery is almost fully charged and the current that it draws from the alternator will drop off lower and lower to a point when the battery is fully charged.

frogslapper · #10 10-10-2008, 08:31 PM

Every thing said above is 100% true.But just to add more to your first queston.The vt commodore also came out with a mitsubishi alternator that put out even more power that is a bolt on fit.The wiring needs changing but can be done very easyly.This alternator came out on police cars,taxis and some telstra cars,much better then the bosch.

rcnugget · #11 12-10-2008, 07:25 PM

hrm yeah they sure do fit, I went from 90 to 120 also straight bolt on for me in a SII VS $35 from capalaba wreckers. Runs tripple batteries heaps of neons, 4 driving lights and 2200W RMS stereo, wouldnt mind the stinger 250A one tho but $1800 for an alternator is stupid, I think I would have more success in mounting a second alternator inplace of the air con

frogslapper any idea of amp output on that mitsi alternator ?

regarding the cranking thing mines used to take 3-4 seconds to start, new injectors and always about 1/2 a second