I've been finding my battery dead the last few weeks amongst a bunch of other issues(tires,brakes,maintenance, inner tie rod). I've been having issues w/misfiring & believed it was bad gas cause she has good fuel pressure/good spark/air. I drive @ night for work with a heavy load of electricity due to weather(wipers,heat,brights,foggies,rear defogger,GPS,head unit,map light). She's charging @ 12.9v @ idle w/light load & 12.78 w/heavier load but after a while of driving @ night w/heavy load she'll sometimes flicker headlights @ idle/stop sign or start to miss like she has bad gas cat is clogged. The belt tension is correct/newish belt & she'll stay running when you disconnect battery cable. So I'm thinking that the regulator is on it's way out...Any opinions/suggestions?

 

If you are finding a Dead Battery as often as you say I would start with having a Battery Load test done. I would use a Battery charger to get it fully charged then have a Battery Load test done on it. ( Garage or local Mechanic should have this type of tester) It basically consists of a High Current Resister that causes a draw of about 100A on the battery for 5 to 10 Secs and the Voltage Drop is indicated. Anything under 9 Volts under load would indicate a weak or bad Battery that may not accept or hold a Charge.

When Battery has low Voltage the Charging system should indicate a voltage at the Battery terminals of over 13.2V with no load. So if you can pick up a Battery Plug in indicator that plugs into your Cigarette Lighter you can monitor the current charging Voltage. Some of these plug in Monitors have different coloured leds others have a Digital read out. Packaging should indicate recommended Voltages.

Hope this helps

 

It could very well be the voltage regulator but have you checked any electrical connections lately, I mean you do live up north where salt and corrosion can get at anything or anywhere.

Alternator should put out 13.95 to 14.05 volts with no load. You're alternator is not putting out enough voltage to keep up with the electrical draw you are demanding from the charging system. A bad voltage regulator, if shorted, can cause this symptom and can also drain a battery whether the engine is running or not.

 

The alternator is dying. The voltage output of the alternator should be 14 to 14.5 volts. Get it replaced ASAP.

The battery may or may not be bad, but it won't hurt to get it tested.

 

Appreciate ur contributions... I rigged up some leads for my fluke MM to plug into cigarette lighter jack a while back for reason mentioned. One of the first things I did was a battery load test and there's no parasitic drain.

 

From the info I gave both of you came to same conclusion that I came to and this is the confirmation I'm looking for...I'm going to swap out the alternator for a reman/new one. Thanks for the help guys...

 

If you haven't already started replacing it, it may be beneficial to do a voltage drop test. Reason being, with these Maxima's being older, they tend to build up corrosion around the terminals. .25 volts is the maximum you should see when doing a voltage drop test.

 

Check your connections man, sounds like you got a bad ground or loose wiring!

 

I clean everything under the hood and coat with dielectric grease and I did a V drop test. I left out some of the test I ran...my bad, this issue get serious after a few hours of driving @ night w/heavy load.

 

No don't take off the terminal with the car running ever not on these cars if you didint need one before your probably gonna need one now clean the connections see what happens

 

Rigging up your MM to get the charging Voltage while you are driving is a good start. What Voltage value were you getting.

A Battery Load test checks the Condition of the Battery when on a Heavy load condition.

Here is one type of Meter that can do this. It applies a Low Value resistor on Across the Battery to cause a 100 Amp draw, the Meter records the Voltage across this resistor. After about 10 sec of draw an voltage lower than 9V would indicate a defective Battery if test were done on a fully charged Battery (between 12.6 to 13.2 Volts)

This meter can also be used to check Starter Cranking performance and as has been mentioned by other Charging System voltage of 13.5 to 14.5 V

 

Nothing will happen if you pull the (-)terminal while running...if the alternator is bad it will stall, if it's functioning it will run off the alternator. I went to automotive school for 2 years and have been in this field for many. I started thread to see if anyone had a misfire issue related to alternator issues mainly...your car can run on as low as 9.6v according to the factory, after that the ECU will not function properly or at all. I wanted to see if anyone had experienced this with the factory alternator or at all. I believe the fuel injector firing order signal is off due to low charging output due to heavy load after hours of running.

 

Thanks bro but it's not a battery issue...the regulator is failing during heavy use/load.