I recently installed an Eagle High 250amp H.O. alternator in my 2015 Altima.
Immediately upon starting the engine my battery light came on.
I hooked up my OBD-II scanner and it shows that the CPU voltage with the car running is @ 15.6v.
Using a Fluke DMM I tested at the alternator and it is in fact charging @ 15.6. This is all taking place in single digit temperature, but I doubt it would have that drastic an effect on charging voltage.
I'm running 3 batteries, 2 of which are only months old; suspecting that the older of the 3 might be the issue I removed it from the system but the charging has not decreased at all. I'm running an Optima redtop 35 under the hood and 2 Kinetik HC800's in the trunk.
I installed this alternator to feed 1700w RMS worth of amplifiers, but my subwoofer amp goes into protection mode as soon as I start the car now. I asked the alternator manufacturer and they assured me that 15.6v is within their operating specs. So, I guess what I'm asking is; Is there a device on the market that will step down 250amps to 14.4v? All I've been able to find is the XS Power 993, but it is only rated for 50 amps. Any help would be appreciated