: Alt amps too high?

01-27-14, 05:16 PM
Hello Every one.
My '99 eldo (base model) alt, at engine start up wants to charge at 14.7 to 14.9 and maybe higher if I don't turn on seat warmers and a full pull on the headlamp switch. I don't pull the lights on unless it acts like it may go up to 15.0..After 6-10 miles (after engine temp)3/4 running temp at goes down to normal 14.2- 14.4 I start turning down assy. and the amps stay in place. Should I worry? Should I check battery level? The battery is a 800 cca and 10 months old. It's a well maintained car....
I thank you for your advice.:thumbsup:

01-27-14, 05:24 PM
You're not looking at charging Amperes - you're looking at electrical system Volts.

The voltage regulator is functioning normally ............. The car will start and the regulator ramps up Volts and Amperes to charge the battery and carry the electrical loads - you turn more on and you simply load the system to its capacity.

It is perfectly normal to see Voltage ramp up to 14.6 - 15.0 for some period of time. As the battery approaches full charge the regulator ramps down Amperage while maintaining high voltage. Closer to full charge, the battery internal resistance rises, the regulator senses this and ramps down Voltage to a normal running figure of 14.0 - 14.5 or so while keeping Amperage at a value high enough to carry the electrical loads present at any given moment: You turn on headlights, Amperage increases; same with any other loads on/off.

It's all magic.......... all you do when you turn on more loads mistakenly is lengthen the time to full charge - and burn more gas: It takes quite a few horsepower to turn that alternator/generate electricity - and that takes gas to accomplish. Believe it or not, headlights/fog lamps on = lower fuel economy.

EDIT: To watch Amperage in our cars would take an analog ammeter, with shunt, inserted in the main (red) charging cable from the alternator.

The third paragraph - charging voltage/amperage sequence, is based on experience with my STS and 4 other similar Sevilles/Devilles that I maintain/help maintain. One in particular, a 2001 DHS, is fresh in my memory because I replaced her battery 2 weeks ago, just before the Great Snow - and drove it a half hour for checkout.

Look at it this way: To keep the same value on the speedometer ("volts") in hilly country it takes variable gas pedal (amps) application. Your car's electrical loads are a never-ending series of peaks and dips, and the regulator does its best to smooth them out.

01-27-14, 05:27 PM
Your numbers are good. If it started going toward 16 volts, or below the mid 13's, there's a problem.

Oops, sub beat me.
(Got distracted, didn't hit post :yup: )

01-28-14, 11:28 AM
Thank you both, this site is great because of the accumulated knowledge available. I will cease my attempt to regulate my eldo's intelligent charging system. Perhaps I should just enjoy the comforts of ownership and stop worrying hummm.... I bet that's where mpg went from 22.1 to 20.? I thought it was winter weather related, turns out it was because of the frost between my ears!! thanks again, Ed

01-28-14, 11:54 AM
Gas mileage is a moving target - the recent weather in the cool/cold states is responsible for decreased fuel mileage - and increased electrical load(s) factor in there, too. An alternator and A/C compressor combined can easily use up to 10 hp in normal driving - and you push down the gas pedal to offset that 10 hp extra load. If your car needs 60 hp to run it down the Interstate at 65 (that's actually a close figure) and you add extra engine/electrical loads, maintaining enough horsepower to keep the same speed comes from somewhere - the gas pedal.

01-29-14, 01:01 PM
I left everything alone this morning , after about 10 miles the alt meter came down to 14.5 by itself, another 8 down t0 13.9 ...I'm satisfied.... Ed....I'm going to post a question about switches in about 2 min. thanks again