Altenater replacement?

[mexillis]

So I recently installed a new battery and I feel as if the altenator is going bad. Has anyone replaced one yet on the M45 06/07 model? What is a typical life span of one? I know they make high output altenators but not sure if it is necessary since I do not have a sound system anymore. I suspect it going bad based on the cig lighter tester shows it at 13.2 instead of 13.4+ along with no ability to use my remote for accuair while the car is off. Before it would allow the compressor to run for a short time for airring up the vehicle and now it shuts off immediately. While researching do any of you think this might help? Quoted from crutchfield.com:

"A good, cost-effective improvement is to perform the "Big Three" electrical upgrade. This will vastly improve your vehicle's electrical system, allowing more current to flow easier to all components. This upgrade replaces or augments three key cables in the electrical system with 1/0 or 4 gauge wires: the battery ground to chassis wire, the chassis to engine block wire, and the alternator plus to battery plus wire. This increases your electrical system's current flow capability, ensuring a more consistent voltage under varying demand conditions."

Thanks for any input.

[TDot]

I may be wrong, but I don't see how the alternator will help you while the car is off. When the car is off, the battery does the work. When the car is on the alternator does the work.

The big 3 could help your situation I guess, but if it worked before without the big 3, why would it need it now for it to work? Either way the big 3 is always a help with aftermarket power hungry things regardless. Sounds like something else is wrong to me...but you never know.

If I had to choose between the two I would start with the big 3 before the alternator.

[mexillis]

That was my thought process too. car off -battery on -alt. Nothing has changed besides I have a new battery now and the cig lighter test telling me 13.2 but those things are cheap and IMO unreliable. HO alt dont exist for our car either, just checked. The big 3 sounds easy to do and I have spare 4 gauge in my garage, def will attempt that before a new alt.

[TDot]

Also, maybe the ground to the new battery isn't seated and tightened well, or the battery isn't as good as it can be.

[svard75]

A stock alternator will output just a bit over
35 A at 1300RPM
105 A at 2500RPM
136 A at 5000RPM

Disconnect the Positive terminal of the alternator and connect a multimeter inline between the cable and the terminal then set the multimeter to DC Amps and see if it's lower than it should be. Alternatively you could look into replacing just the brushes as that is the wear part of the alternator. Reading voltages doesn't really give you the true picture of the alternators efficiency especially at the lighter socket. You are actually reading the voltage from the I-PDU and I'm sure there's a voltage regulator built into it.

[EniGmA1987]

Wouldnt you have to have a pretty special multimeter to read that kind of amperage? Most I have seen are only rated for an amp or two at most.

[szh]

Wouldnt you have to have a pretty special multimeter to read that kind of amperage?

Definitely! The simple low ampere meters need to be in series with the current - not easy in a car on the battery or alternator.

What you need is one that clamps around the wires and uses induction to "measure" the current flowing in the thick wires.

Although I should add that they are not special per se ... in the sense that you can get them pretty easily from some electronics place. Heck, Amazon probably has them.

Z

EDIT: Yeah, something like this: http://www.amazon.com/Fluke-323-True-RM ... amp+meters

[svard75]

You're right. Thanks for correcting me.

[veery]

I would triple check the battery connections, and make sure they are clean too. 13.4, 13.2, is not enough to make a difference. Check the voltmeter when you turn on the lights - if there is a big drop, have your battery load tested. (or do that anyway - battery shops will do if for free)