Battery light comes on and the van is making a deep whistling now

change alternator and maybe battery. Since the battery is pretty new, draining it like you say only took a year or two off its lifespan. Remember how your car acted this time, as most newer cars do the same exact thing when the charging system or battery needs service. In the future, you will recognize the symptom and know where to look before you get stranded.

It very well could be a vac leak or a problem with the air filter box.
If you can make the sound happen sitting in park, have someone listen around the engine compartment with a section of heater hose while you operate the controls.

sounds like you have a squealing wheel bearing.

The symptoms match those of wheel bearings getting worn out. One sure way to determine it is not coming from the transmission is by taking the vehicle to a decent speed, say 35 MPH ,and put it in neutral. If the humming continues unchanged, then it comes from bearings, and if it drops, then it might come from transmission or engine. 135000 miles is way over the life expectancy of a set of bearings.
If the bearings are starting to fail, they produce a high pitch sound, almost a whistle, and if they are almost gone, they produce a deep rumble. High speed turns might subdue the sound, or make it worse, depending on if you take weight of bearings, or increase it.

ensure that your exhaust pipes do not have a problem. as you accelerate more explosion comes out the exhuast pipes and if there is a "hole" in it then the whistle will get louder as you accelrate more.

I took my car to Keller's Auto Repair in Gettysburg PA, He specializes in Chryslers. I have 04 Cruiser with 2.4 Turbo that had the same whistle noise, and check engine light on. He found code P0301. The noise was caused by the #1 Cylinder injector O ring. Check them out on facebook. They will help you.

http://www.facebook.com/#!/pages/Kellers-Auto-Repair/158207620880499

sounds like a wheel bearing but to be sure jack up the truck and wiggle the tire from top to bottom if it moves then it is a wheel bearing

This either means your battery has failed or the alternator. You can use a voltmeter to monitor battery voltage it should maintain at least around 13 with lights on if it gets low and car eventually stalls replace alternator. Thanks

Are the windows up tight and sealed?

Hi all,
I currently own a 2005 saturn vue and also a 2002 saturn vue. My 2005 began making the same whistling sound around 36000 miles, I let it go and let it go. Finally it got so bad I could not deal with it any longer, I have a great mechanic and he automatically point out the carrier bareing I had it replaced and my car is very very peaceful...... :) Hope this helps.