Alternator Voltage Dropping.

[FiQ150db]

This is the exact alt I have on my car: http://www.highoutputalternator.com/PDF/We...Fs%20-%206G.pdf

My problem is it starts at 14.5+ when I start my car but after a while it drops down to 13.6-8v. Its spliced into my cars charging system.

Any reason for that ?

At the moment only running 1 55ah yellow top and 1600wrms with 0awg.

[Guest KyleCannon]

What is your car idling at?

It can be that the alternator is getting too hot and it's regulating itself so it doesn't cook in your car. Mine for example on a cold start it 14.8 and after I am done bumping my music it can drop to 13.8 depending on the day. I also am guessing that you're having an idle problem as well so let us know what your car is idling at.

[FiQ150db]

The car idles at about 800rpm which I assume is too low for an alt of that size (my car is a 1.6) as sometimes I believe the alt turns off and voltage drops to 12.x the revs go below 600rpm and it then pops back to life.

Usually when I blip the throttle to about 1100rpm there is always a voltage increase of 0.1v

[roscoe1129]

it could also be belt slippage, if theres not enough belt on the pully when the system needs more juice the alt loads down and could cause slippage. Also your factory regulation for the car may be causing it to tone down the output voltage. A MLA Module could help in this application.

[FiQ150db]

Apparantly a MLA module isn't available for me as the alts been wired up via a one wire set up ?

[Guest KyleCannon]

I would say check belt slippage and maybe put a couple of drops of water on the alternator and see if it sizzles... that tells you that the alternator is really hot and it might be the cause of lower voltage. Or, it can be one of these:

Pully is too big so you're not getting enough alternator RPMs

Pully is too small and you're getting belt slippage like Roscoe said

Alternator is backing down because it's too hot. (like stated above)

Car's computer system is making the alternator back down.

Try revving the engine to 2 thousand RPMs and full tilt it and tell me what the voltage is and if it comes back up.

[FiQ150db]

When playing music on full with long bass notes voltage goes to 13v and stays there.

The pulley on the car is the standard pulley taken from the original alt.

[missinglink]

We will look into the alt and may want a few installed pics to help get you some options. People use smaller pulleys to bump up alternator RPM but can cause belts to slip. If your voltage is dropping when your alt gets hot its the alternator protecting itself by reducing voltage and output in most cases. Its common to see some drop , as for how much or how fast it drops that the alt doing its thing. Either it can keep up or it can't its that simple.

Hope this helps,

MLA

[FiQ150db]

I'd appreciate if you could find out if theres anything available for me as ideally I'd like to get it sorted before my build starts (3 weeks).

Only reason I can imagine the alt getting hot is because the battery is in a poor state (floats at 12.3 car voltage system and h/u reads 11.9v) thus its outputting fully for too long causing it to heat up ?