So, does the car dies on you while drivng on each alternator change? Did this start happening after you replaced the original alternator? And if you are just exchanging the same brand and model alternator I would suggest returning that to Napa and get a different brand from another retailer altogether. ( if Napa only has one brand for your car). I personally have experienced a bad batch of alternator from kragen on my previeous car. It was the voltage regulator flactuating within a few months. After swapping out the same alternator several times in a span of <2 years kragen change brand/manufacturer and all issues disappeared. Good luck.

 

Start checking your ground wires. Unfortunately on the Murano I don't know where the major grounds are (someone might be able to help here) but this sounds like a grounding issue to me.

 

Agree with Jays, check grounds and terminals for corrosion and proper connection. Also does your battery hold charge on its own? May not be the alternator as much as it is the battery.

 

If a voltmeter across the terminals of the battery right after starting the car shows 13.8V, then your alternator isn't working...or your battery isn't accepting the charge.

Normal alternator voltage output when cars are running is a bit above 14V. In the Murano I have learned that the voltage output from the alternator will drop below 14V while running if the battery is fully charged, but right after startup when you're calling on the battery to start and it needs to be recharged, I would expect to see at least 14V with a voltmeter on the battery terminals.

When you put a load on, the voltage should go UP, not down.

My conclusion: your alternator isn't charging....or if it's charging, it's only doing so partially....and if it's only charging partially, the cause could easily be a battery that won't accept a charge.

What I would do is charge the battery fully overnight (every garage should have a good battery charger, so get one if you don't have one) and check the voltage right after you pull the charger off. If it's under 12V, replace the battery - it's shot. After a charge, the battery MUST have more than 12V.

Drive the car 10 miles or so, park it and turn it off, then check the battery with a voltmeter again. If under 12V, replace the battery.

I'm not sure where the problem is, but if you've had the same battery through three alternators, I'm inclined to think the problem is not the alternator...and from this forum I've heard many, many stories indicating that Muranos are very sensitive to worn or degraded batteries.

 

Thanks for replying everyone. Ive checked the grounds (that i could find) and i found one busted off that runs to the top of the transmission, the same spot that the battery is grounded to. replaced that at the same time i put the 3rd new alternator in. Ive had the same battery since i bought the car about 3 years ago. So, i wont rule that out yet as i havent had time to let it fully charge on a charger yet. The weird thing is, before i put this last alternator in, I went out to move the car and it wouldnt start, just went click,click,click, like the battery was dead, so i let it sit for about 20 minutes and then it started right up. It also went into "limp" mode after i got it started and then would stall out. This repeated itself a few times in the driveway. After 3 days of sitting in the driveway I started it up and drove 25 minutes to change the alternator and it worked perfect. is this signs of a bad battery..??

 

snipe:

Ive had the same battery since i bought the car about 3 years ago. So, i wont rule that out yet as i havent had time to let it fully charge on a charger yet.

You cannot tell if a battery is not problematic by putting it on a battery charger. You need to fully charge the battery and then properly load test the battery with a load tester.

Cut to the chase in regard to your Murano's electrical issues. Charge the battery, Load test the battery to see if it is aok OR just go out and buy a new battery. You are overdue for a battery. DO buy a battery that is rated a bit higher then the recommended battery for your Murano.

By the way, a bad battery goes hand and hand with the symptoms you mentioned in your initial post in this thread. Goes hand and hand with your topic title "New alternator doesn't charge under load".

Others here were correct in telling you to make sure all grounds were aok along with connections to battery itself.

Take a moment to view this video.. The fellow brings up some basic points that you will find useful/informative.

.

 

I'd say the battery is shot...but I still suggest a full charge on a battery charger.

 

Its always helpful if you give a more complete description on the problem you are having. A 3 year old battery is on its last leg if not yet dead and very unreliable. If your sole basis for alternator replacements is the reading that you got from your battery charger voltage meter with that 3 old battery then its probably wrong. When troubleshooting a problem, exhaust all possiblities first before any parts replacements. Even without using any multimeter, tell tale signs of alternator issues is seen when driving the car. It dies on you is one of them and/or power flactuations on your electricals like radio or lights. Signs of battery issues on the other hand is mostly seen on the starting of the car. If you hear any weak crank or no crank or "click click click" like you said, are a couple of them. Sounds like you swapped out too many alternators unnecessarily. Change your battery first and see what happens. Good luck.

 

Agreed. "Click click" means your battery is too low to operate the starter (it's the solenoid clicking that you hear) or you have poor contact with the cables. In your case it points at the battery...but it never hurts to make sure the cable contacts are clean.

The question is: WHY is the battery too low? If you have been driving it for more than 10-15 minutes, it should never be too low to stop and re-start. However, an alternator cannot charge a battery that is shot, nor will the battery hold the charge.

 

I second Bill's suggestions.

I also second the concept of buying more battery than the minimum. I have long followed the practice of installing the most powerful battery that will fit in the space available.

 

if it smells like a battery and tastes like a battery...

this is why I mentioned it once. People are always so reluctant to check the easy stuff, like it's so hard to believe that the problem could be a piece of 100 year old technology you can buy at Walmart.

 

This is the 3rd alternator ive tried, its a bosch from Napa.
It charges 100% when the car is just idleing, no accessories on at all.
As soon as I start putting load on (lights, heater, heated seats) you can watch the voltage drop from 13.8 down to 12.4 or so, slowly. My battery charger indicates that the alternator is working at 0% and slowly drops the battery percentage as well. As soon as I turn OFF the accessories, voltage goes right back up to 13.8 and holds. Could there be something else wrong with the car other than the alternator thats makeing it do this?
Its a 2003 SL AWD.

-Brandon

I have the same issue right now, on my second alt with a new battery, did you ever find out the fix?