I have a 1999 Accord with a 2001 Odyssey alt. I parked my car about a 90 minute trip and when I went to roll up my windows, my HIDs turned off while holding the switch. Then anything electrical I touched, my headlights would turn off along with my radio. Once I got onto the highway, the car started charging at 14.9-15.1 volts and I couldn't do anything to lower it

Engine ground, alt ground, and battery ground are all the highest end 1/0 wiring that exists. No loose grounds anywhere. I can't figure out why my headlights turn off when I touch the window switches and climate control, or why the voltage won't come down. The digital volt gauge has been calibrated with 2 different DMM and is hooked up to the battery + terminal

Before anyone blames the alt for being too big, it has been in the car since March with no problems at all

 

How do you know it's charging too high? Did you stick a voltmeter on the charge wire and verify that it is indeed 15volts or are you going by a factory gauge? If the alternator is creating an over-voltage issue, it is probably the voltage regulator. Have it tested by a qualified person.

 

Sounds like a bad voltage regulator. Was it a new part in March? Can you pull it and have it bench tested?

 

^ Exactly my thought!

 

15.1 volts is the maximum acceptable voltage at 2000 rpm, at least in the 1993 Accord according to the troubleshooting flow chart in the Helm manual. I don't think that has changed.

With the grounds being good (good on you for checking those out) I don't understand why the HIDs and radio are kicking off. It may be that the 15.1 volts is too high for the conditions.

The mysterious ELD circuit is only part of the ECU management of battery charging. In the 1993, for example, the voltage stays boosted unless the load is below 13A, vehicle speed below 43 mph, engine speed below 3000 rpm, engine coolant above 167F, A/C switch off, Intake Air Temperature above 68F, the brake switch is off, and the fuel cutoff control function is not engaged. If any of those conditions are not met, the higher voltage is used.

 

When I had 3 batteries in the car, voltage would be in the 12's once I started to accelerate from a stop but once I got into 5th gear and started cruising, the voltage would come back up to 14.4 volts. Or if I turned the headlights on, the voltage would automatically come up to 14.4 and stay there. Same thing with the climate control. I figured it had something to do with fuel consumption

Is there any way to tap into the circuit and run an external voltage regulator?