3

thanks in advance!

I have a 2007 Nissan Murano SE. The primary symptom is it literally loses power while driving, going into emergency mode before finally dying all together. But no low battery indicator ever comes on.

I just got a new battery and AutoZone tested the alternator output and their tester device said the alternator is working fine.

I've thought about parasitic drain but not sure what parasitic drain would be so strong is to kill the battery while driving.

If I fully recharge the battery, the car seems to run fine for a day or two, but clearly the battery is not being recharged.

Again, my first thought is the alternator but the alternator output test says it's outputting fine. So if you have any ideas I'd appreciate it. Is there a fuse or relay between the batter and the alternator?

Thanks again.

2
  • The first thing I would do it take off the battery terminals and thoroughly clean the posts and terminals to make sure you have a good connection.
    – GdD
    Apr 16, 2023 at 17:45
  • Thanks, did that when I got a new battery, everything is clean as a whistle. Apr 16, 2023 at 17:57

1 Answer 1

2

The 2007 Murano has a fusible link attached to the + battery terminal on the black-red wire that goes to the alternator's B terminal. A fusible link is just a heavy duty fuse.

If the fusible link has blown, your battery won't charge, but it will supply power to the car until it's exhausted.

To prove that it is bad before you replace it, turn off the engine, connect an ohmmeter between the battery + terminal and the alternator's B terminal, which has a red-black wire. The ohms should read 0 or nearly zero such as less than 1 ohm. If there is no reading (infinite ohms), the fusible link should be replaced.

It's never a good idea to let an alternator charge a nearly dead battery. Better to use a battery charger to at least partially charge the battery before letting the alternator finish.

2
  • If the fusible link is blown, would the alternator have the power to energize it? Apr 16, 2023 at 18:06
  • @Pᴀᴜʟsᴛᴇʀ2 We don't know how Autozone tested the alternator. Do they have an alternator tester that supplies 12V directly to the field coil? Dunno. But in real life a DC alternator can bootstrap sufficient voltage to operate based on a residual magnetic field left from the last time it ran. Household generators (really brushless alternators) rely on this principle to start generating (alternating!) without a battery to supply the field coils.
    – MTA
    Apr 16, 2023 at 18:16

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .