I'm putting in an AGM battery which requires a special charging profile for optimum lifespan. Is the regulator output voltage adjustable, or is it possible to replace the regulator with a smart charge controller?

I've read that some Lexus models have the alternator output controlled by the ECU (not sure about the GS though), and so it would seem that this might be impossible. Right now on the old battery, the voltage shows about 13.5-13.8 while running, which is far too low for the AGM bulk and absorb stages. I'm getting an Odyssey which requires 14.7v for bulk and absorb, and 13.8 float.

 

no time to upgrade the alt as well

 

It's 150 amps from the factory, right? If I replace it, will I have any error messages to worry about? I would figure that 150 amps would be plenty enough, if I can get access to the field wire to hook it up to a charge controller.

 

The charge controller that I was considering is a Balmar MC-614, which is more often installed in boats, but should work for a car. I'm just trying to figure out whether I need to replace the alt just to get the controller to be compatible, and whether doing so would set off any ECU codes or anything.

Anyone that knows about the stock controller and charging system please do speak up - especially if it can be programmed!

 

rkenimer.... If you find anything LMK! Our cars like to keep stock voltage no matter how you put it. The alternator is controlled by the ECU of the car I believe.

After you pass a certain threshold, your car definitely has batt lights and maybe CELs go off.

This has been tried and tested by a few Lexus owners and Steve Meade himself. So they just ate it and stuck to factory voltage with higher amperage from Mechman.

The extra amerage helps a lot but the voltage will drop a bit during heavy amperage loads.

 

Shoot, even if this is the most active Lexus forum on the internet, there doesn't seem to be very many people that know about the electrical nuts and bolts of our cars.

 

That's because most of us, (admittingly myself for the most part) would rather send our cars off to the shop to get'er done

 

Well I installed my new battery and the voltage is much higher now. Maybe the charging system has some sort of smart controller that can detect the battery type? No idea. Maybe the old battery was dragging down the regulator voltage because it was on its last legs. Engine starts much nicer now in the cold.

 

Nice! I'm due to install my alt sometime soon. It's driving me nuts that it's just sitting in my room