car electrical troubleshooting - alternator, starter or battery?

[Stand_watie]

This is on a 2009 nissan versa 1.8 liter.

Backstory, I went to start my car monday and instead of turning over it sounded as if the starter were spinning without engaging. I put the charger on the battery and it started right up. I put the charger on the battery overnight at work and it has since started 6 or 7 times with no problem. In between the starts I put 250 highway miles driving to and from work.

I had the battery checked at two places this evening and both say 'good, fully charged'. One place said the alternator is only producing 70 amps, when 100 to 110 is called for. Battery appears to be original, and as such would be 5 years old.

So my possible problems that I have so far thought of...

1. Battery was discharged due to door or something being left open, nothing wrong with battery.
2. Battery malfunctioning and not showing bad on the test equipment at auto zone/o'reilly's
3. Alternator putting out enough to keep battery fully charged with mostly highway driving, but not keeping up battery charge with stop and start driving.
4. Starter intermittently malfunctioning with battery boost pushing it from not working to working.
5. Some combination of these factors.


Any other ideas would be welcomed. I can afford to make neccessary repairs, but not to pay for parts just hoping that I'll get lucky.

[Regolith]

IIRC, one of the tests is to check the voltage at the battery with the car running. Should run around 14 volts. Much lower than that and either your cables or your alternator is bad.

[never_retreat]

5 years is old for a battery. Might have something going on internally.

[Stand_watie]

IIRC, one of the tests is to check the voltage at the battery with the car running. Should run around 14 volts. Much lower than that and either your cables or your alternator is bad.

Was getting 12.9 volts. I've been driving with my battery charger in my trunk.

If I bought a new battery and kept it in my trunk until I'd determined for sure the problem, would roadside replacement of the battery give me enough juice to drive 50 miles or so if it turned out to be the alternator and alternator quit charging completely?

[bedlamite]

Was getting 12.9 volts. I've been driving with my battery charger in my trunk.

With the car running or off?  Off, 12.9 is excellent, running, it's bad.

You might also want to check for loose/corroded connections on the starter solenoid.

[Stand_watie]

With the car running or off?  Off, 12.9 is excellent, running, it's bad.

You might also want to check for loose/corroded connections on the starter solenoid.

I don't recall, but when the sun comes up I'm going to go check it both running and off. Thank you for the suggestions.

[CNYCacher]

"Hey I don't know if my starter, alternator or battery is bad."
"Is your car 5 years old?"
"Yeah it is."
"It's the battery."

I have this conversation all the time.

[dogmush]

"Hey I don't know if my starter, alternator or battery is bad."
"Is your car 5 years old?"
"Yeah it is."
"It's the battery."

I have this conversation all the time.

This^

[Hawkmoon]

How many amps the alternator is putting out doesn't matter so much, and probably isn't a valid indicator of a failure. As noted, if you test the voltage across the battery terminals with the engine running, the reading should be at least 13.4 volts because the alternator is working to recharge the battery as fast as the juice is being used up. The amperage only tells whether or not the alternator can keep up with the draw of multiple accessories.

How far you can drive on just battery if the alternator is dead depends entirely on what's being used. On a cool day where you need power only for the fuel pump, engine fan (which probably wouldn't kick in on the road), ignition and injectors, you might get fifty miles out of it. On a cold or hot night, where you would also be running the headlights, ventilator fan, and perhaps a/c -- fifty miles IMHO would be a real stretch.

[K Frame]

As a friend once said...

It's the Basternator...

[Tallpine]

I would just replace the battery.

The starter spinning but not engaging probably means it wasn't spinning fast enough to make the drive gear pop out and engage.

FWIW, I have seen both batteries and starters test out just fine on the bench, but fail to actually start the engine.

[Nick1911]

My money is on battery, but check to make sure it's actually charging, 13.5-14.4 while running is good news.

One time I preformed that test and got 19 volts.     voltage regulator that supplies current to the alternators field winding had failed closed.

[Monkeyleg]

At five years old, the battery is going to need to be replaced soon. You might as well do it now. Any tests that can be done on the alternator will require a fully-charged battery anyway. If you're trying to squeeze the last few months out of the battery, charge it completely and take it to AutoZone or another store and have it load tested. They should also be able to check your alternator output.

[geronimotwo]

^^^what he said,  they can do it with the battery still in the car, and they don't charge anything.  i use the local napa store.

[Stand_watie]

Update - I replaced the old battery with a new (larger), old battery is in the trunk for a couple days until I figure out if I've solved the problem.

The old battery showed 12 volts with engine off, 15 running. The new battery shows 13 volts with engine off, 15 running.

[Lee]

5 years out of a Nissan OEM battery is nothing short of a miracle. I'd get a new battery. Actually I did just replace my 3 year old Nissan's battery...as did my neighbor with their 3 year old Nissan's battery.

[Brad Johnson]

Update - I replaced the old battery with a new (larger), old battery is in the trunk for a couple days until I figure out if I've solved the problem.

The old battery showed 12 volts with engine off, 15 running. The new battery shows 13 volts with engine off, 15 running.

Voltage with no load really doesn't tell you much. Checking the voltage under a load is a much better diagnostic.  Check voltage with everything turned off (it should read 12.5 - 13.0 volts) then flip the headlights on high and watch your meter.  If you see more than a half to three quarters of a volt drop the battery is marginal.  If it immediately drops by about two volts then you have a failed cell.  When a cell fails the battery may show full voltage under no load, but the cell goes by-by when load is applied (2.2 volts per cell, thus the 2 volts drop tell-tale).

Brad