THE light is part of the charging circuit
If you want to diagnose, that is where we start
Does the bulb come on with key in run?
Does go out when running?
Next will be a meter
You have one, do you know how to use it?
I don't remember for sure if the light comes on when the key is in the ON position prior to ignition, but it's not on while the engine is running. Today I tried to check and see if the wire was loose, and I've noticed that if I pull the (stator?) plug completely out, the battery warning light doesn't come on, like it used to previously.
Originally Posted by Michael Plummer
An alternator needs 1800-2000 RPM at idle to make power and will make maximum output at 6000 rpm but will FAIL at 16,000 alternator pulley RPM
Measure Alternator pulley size (for example 2.5")
Measure Crankshaft Pulley Size (for example 5")
The Ratio is 2:1 (5 divided by 2.5 = 2)
To find MAX RPM: take your Max engine Speed (for example 5800 RPM) and multiply it by the calculated ratio (5800 x 2) = 11,600 shaft RPM
To find IDLE RPM: Multiply Idle RPM x Ratio (for example 1000 x 2) = 2000 shaft RPM @ Idle
Other things to look at:
1. Powder coated alternator bracket or alternator? Is mounting hardware clean and free of rust?
2. Visual inspection: Look for loose alternator connections and damaged/cut cable/wiring. Also check your battery for a loose connection.
3. Electrical test: Check your battery for over & under charging while under load and no load conditions.
4. Fusible link
5. Is your alternator sized correctly?
Based on the measurements of Crank Pulley (6.5 inches (165 mm) diameter = 20.41 inch circumference) and Alternator Pulley (2.2 inches (56 mm) diameter = 6.91 inch circumference), you end up with 2.95 ratio. This means that at 6500 rpm at the crank, I'm seeing about 19200 rpm on the alternator. That is quite a bit higher than previously mentioned 16000 rpm limit. One thing that still didn't make sense to me is why did the alternator work the whole time prior to this, and I had to go back and really dig deep into my memory. I remember that this all started, when I changed from conventional battery to a sealed cell small battery (Odyssey). When I went to a full size battery to try and fix this issue, the battery type was still sealed cell (Optima), not regular battery like the kinds you'd get at the parts store. My theory is, that maybe a regular non sealed cell battery allowed for something to happen that would put the excess stress on the battery itself, because I do specifically remember that battery would always have corroded posts, melted corroded cable terminals and at some point there was corrosion forming at the bottom of the battery tray, because the acid would spill from the battery itself. I wasn't sure if that was due to overcharging or dealing with lateral g-forces, but something was causing battery to get seriously affected.
1. Mounting hardware and brackets are all clean and rust free
2. No visible damage on either the alternator or the wires running to and from the alternator
3. Have not performed the test, will do so soon
4. Not sure what fusible link is
5. The alternator was ordered for the specific application of 94-95 Mustang GT, so I can only make an assumption that it's the correct spec.