After a week of taking the alternator off my car, I decided to have it checked before purchasing a new one. During that test, I recall seeing the digital readout at 11.XXX volts but the guy told me that it was still working, although at the very low end. Well after getting through this week with occassional VOLT and BRAKE light (both red lights) being turned on. My headlights would dim down but then it seems as though the engine runs slightly more rough and I hear an whine from the alternator area as the battery is being recharged again although the VOLT and BRAKE lights still seem to be on. So today, I decided to get a battery/Alternator check but the car shut down the first time due to the battery was very bad and testing showed it. So I forked down a small change for a new battery, no big deal. He then ran it again but the new battery showed a low charge of about 11.3-11.4 volts because the alternator was weak at 11.6 volts, well below factory spec at 14.1-14.7 volts. Per the service manual, if the alternator test comes back below or above 14.1-14.7, then the culprit is more than likely the alternator. I'm hoping it is, because last week it was due to an improper ground on the negative terminal

Just sharing stories

 

so, what is the safe or good range to be running in (according to Nissan and according to you guys)? What are the consequences of running a bad alt? How much to replace? Hard to do?

sorry guys, i dont do electrical....

 

A bad alternator will be working overtime to try to at least get to the correct voltage required to run everything. The alternator is very easy to do and it cost about $150 new or about $50 at a junk yard.

One consequence is not having bright headlights and having codes thrown up the ying-yang getting CEL lights due to sensors not getting enough juice.

The factory recommended range is 14.1-14.7 for FED-spec models. I know Cali-spec alternators are 110amp vs. Fed spec at 125amp, but I'm not sure if the range for Cali-spec vehicles are the same. My car still runs at 11.6 volts, so its not necessarily a bad thing, I'm just throwing codes. I can hear my alternator whine so its working O/T to recharge the battery.

To test a bad Alternator, you must first test the voltage between the +/- terminals on the battery. If its below or above 14.1-14.7, then check the voltage on the + side and to a secure ground. If its still not between those #'s, then its your alternator or voltage regulator (which is located internally in the alternator). If that test is between 14.1-14.7, then you have a bad ground or connection somewhere leading to or from your battery.

 

to test: multitester on both poles, or....?

good info though, dude.

 

yes both +/- terminals. If it comes out as a bad battery, I would swap batteries with someone else first to see if its actually the battery. By the looks of it, if it turns out to be a poor or corroded negative wire, its a very easy replacement item that only requires a 10-12mm socket.