Help battery over charge
 

I have a 15 volt indication and a Battery lite as well as a e brake lite any ideas?

do you mean 14.8-15v while the car is on? that's normal. give credit to your alternator.

Over 15.2 at ilde. both came on at the same time

Check system voltage with a multimeter. The dash gauge may be out of calibration.

Edit: You can also check system voltage with an OBD scanner.

That's still high. I think 14.8 is the cap. Otherwise the alternator has issues

With a meter it is 15.0-15.1

As for the brake lite the fluid is not below the add line but not to the full line.

Put it to the full line to make sure. That system is touchy.

And it seems like your alternator is on OD

According to the FSM (page CHG-27 in the 2009 edition), 14.1-14.7V is normal. Sounds like your regulator needs to be adjusted. Check your battery - overcharging can cause the electrolyte level to drop - and add distilled water as needed.

first thing, how old is your battery?

secondly, have you tried another battery to see if thats being overcharged?

hummm... that is high.

no change with fluid added

can you ajust the regulator?

Factory battery, 2010 ish

well first things first, measure the voltage while the car is running at the battery terminals, you might not be overcharging but the car can think you are if the voltage sensor is bad(i think thats what the gauge and ECU uses)

you should read exactly 14.7v if its a little higher or lower, dont worry about it(meaning dont worry about overcharging your battery take the car in to get the sensor replaced if under warranty), as long as its under 15v and above 13.6v, its fine

if you are seeing an overcharged battery, first off take it to the dealer if you have warranty still, either your voltage regulator or your alternator has gone bad and request for your battery to be tested as well, overcharging a battery can lead to bad news(explosions, dead batteries, ect.) later down the road depending on how bad the overcharge is

if dealer wont test the battery, take it somewhere else and have the battery tested, if it isnt passing take the car back to the dealer and demand for a new battery since it was being overcharged

I have 15.0 to 15.2 at the battery running
Car is out of warranty 43K miles
I hope it corrects in the morning, but solid state :(

is that with the stock gauge or a multimeter?

either way if you are getting 15.2 with a multimeter check terminals and make sure they are clean(you can clean them with a wire brush and baking soda mixed with water), make sure everything is bolted up right(no loose cables)

dirty terminals can cause resistance and that can create an overcharge senario

if the battery terminals are spotless and connections are perfect check your alternator, take your multimeter and attach it to the alternator itself and checking the voltage coming out of the alternator, it should read 14.7 or somewhere around that area, if you are seeing more than your alternator is the problem and it needs to be replaced

EDIT if you can take a pic if battery before cleaning it if it needs to be cleaned

I'll work it AM, the only thing I have done is cleaned/degreased the engine last week. I'll reseat all the connectors. I did not get any in the battery area.

let me know how it goes

also did you happen to use water when cleaning the engine? if you did, did you get any around the alternator?

The footnote in the FSM says "*: Adjustment range of power generation voltage variable control is 11.4 - 15.6 V." I don't know that it can be adjusted but it sure sounds like it can.

15.1-15.3V running, if I disconnect the negative battery lead it jumps to 16V

That is less than .1 volts across 6 cells. It should be fine until I can get a replacement this weekend.

Can anyone verify that you get a brake lite with the battery lite? I need to know if this is normal!

Or do I have two problems.

Brake light is probably low fluid level in reservoir. 370Zs seem to be real picky about the level. Fill it to the top mark.

I don't think the two are related but can't swear to it.

Beg/borrow/steal an OBD scanner and the car should tell you what is wrong.

Fluid is full and, ZERO codes

all cells took 3-4 oz of water each. I think it was to late to save it. 3 years +

If you still have high voltage after replacing the battery, the FSM says to repair/replace the alternator. I found no procedure to adjust the settings in the ECM although the ECM does seem to have a lot of control over charging voltage (if I understood what I read). A Nissan dealer can do an in-depth test of the system using CONSULT but I saw no mention of any adjustments.

Copy the battery did not fix it, Alt is on order, 7 AM tomorrow Thanks for all the help

blown 10A fuse at battery fuse block. I hope carquest will take back the Alt in the morning. I am so happy!!!!!!!!!!

Which fuse?

Open the battery compartment, the small fuse block in front of the battery has a pull off top. There are two 10A fuses in the block. One is for the charging system the name of each fuse is cast/molded into the top of the cover.

Fuse #32 supplies battery voltage signal to the "S" terminal on the regulator. Apparently the charging system reverted to its equivalent of limp mode when it lost that signal.

How did you determine it was the fuse? Was there something that lead you in that direction or were you just checking all the fuses?

After picking up the new alternator, I did not want to change it as the GTM supercharger kit makes it an all day job. So before I started I looked for other causes...

Looking at the wiring "Charging System" (CHR-15) I inspectied the fuses, found one blown. I have a FSM and it never even talks about a fuse on the S termanal. Only if you are missing voltage, repair wiring. Nissan did not make this manual easy to navigate.

The other part of troulbleshooting this was the "Brake Lite" was on as well. I also looked at the wiring for that. It is just the switch and the LED. Not connected to the other LED in any wey that you can see in the wiring. After that you have to be getting power to the LED to light both of them from some other path.

I still can't find that path but if I could see the inside of the LED's waring lites I think you would find the two on the same board without any power isolation. Power is sitting on the brake looking for a ground and the battery is the same. The groung came from the voltage regulator when the power was not supplied to termial "S"???

We will never know, but if you wasnted to see what I did, just pull the 10A fuse. I hope this helps other someday. I have to take the alternator back now, full refund from Carquest.

Text from manual

S TERMINAL CIRCUIT
Description INFOID:0000000004457529
The output voltage of the alternator is controlled by the IC voltage regulator at the “S” terminal detecting the
input voltage.

The “S” terminal circuit detects the battery voltage to adjust the alternator output voltage with the IC voltage
regulator.

Diagnosis Procedure INFOID:0000000004457530

1.CHECK “S” TERMINAL CONNECTION
1. Turn ignition switch OFF.
2. Check if “S” terminal is clean and tight.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Repair “S” terminal connection. Confirm repair by performing complete
Starting/Charging system
test. Refer to Technical Service Bulletin.

2.CHECK “S” TERMINAL CIRCUIT
Check voltage between alternator harness connector and ground.
Is the inspection result normal?
YES >> Refer to CHG-3, "Work Flow".
NO >> Check harness for open between alternator and fuse.

Do you see the words "check fuse" in here?

Wow! Thanks for such a detailed explanation.

The FSM usually does a pretty good job but, in this case, it's not very clear what's going on. And I saw no mention of the fuse (#32) in the troubleshooting guide.

I didn't see anything in the CHG section of the 2009 FSM that would indicate that the brake light will come on in your situation. It might show up in one of the braking sections.

Thanks again for sharing your troubleshooting process.

brake light is normal when indicating a charging failure. This happened to my wife's Altima last month. Some worker thought that they were going to take me for 500 bucks at this tire shop in riverside by loosening the charging wire to my wifes alternator and my wife kept getting a intermittent failure. i.e. brake light and engine light. Now this may be slightly different because the voltage is obvious but atleast you know now why the brake light.