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Do I need a new alternator?

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Yesterday, I had to jumpstart my 2000 before going out on a drive (the second time in a month, using the fusebox terminal). I usually warm/idle for 5 minutes but last night, proceeded going out of the neighborhood slow with my a/c on. After 3-4 miles on the backroad cruising at 55 mph, the engine stopped. I was in the middle of a double clutch and noticed the engine did not rev when I blipped throttle while on neutral. I noticed the battery light on the dashboard, so I safely cruised to a stop on the road shoulder. I turned ignition off, and tried to restart. Motor cranked but did not turn, so I threw a lifeline. My wife came to the rescue, car jumpstarted fine, so my 20-30 mile Sunday drive was done near our neighborhood vicinity.

AAA this morning replaced the 8 y/o (2013 installed) Duralast AGM battery (previous one was also replaced at 8 years installed 2005 after PPI inspection). Battery had 50% charge after last night's 30 minute drive with 14v alternator reading. I was told alternator is probably starting to go bad. Car should not have stalled once vehicle was going IF alternator was properly working. There was a brief window of time that it was not supplying the needed charge so the battery was drained during my short drive. I was advised to have alternator checked and would probably end up needing it replaced. My question: Can I still get OEM alternators? I have read, to have rewinding shops have it fixed but how do I know these shops are doing it right? I am 1 hr north of San Fran (Rohnert Park). Any leads or advise greatly appreciated.
 
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Have it rebuilt. A new OEM alternator will be very expensive if you can source one at all.( over $1000) Having yours rebuilt will probably be $100 bucks or so, plus you retain the original.
 
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>noticed the engine did not rev when I blipped throttle while on neutral.

Sounds like a drive by wire issue.

>I noticed the battery light on the dashboard, so I safely cruised to a stop on the road shoulder. I turned ignition off, and tried to restart.

What was the reading on your voltage meter?

>Motor cranked but did not turn,

?? Cranking means the engine is turning...

> Battery had 50% charge after last night's 30 minute drive with 14v alternator reading

How did you determine 50% charge. Where is your battery charger hooked up to?

14V is good

**

as a wild guess based on what you have indicated. I suspect a high resistance short on the main battery wires.

Clean connections on each end of the wires and go from there...
 
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First off, getting a new OEM alternator right now is essentially impossible. They are on back order everywhere. Over the counter rebuilds from places like Rock Auto are also impossible to find. If the alternator is the problem your only option will be to find a local rebuilder or do the work yourself. Its usually diodes, voltage regulator or brushes which are all quite doable by anybody handy with a wrench.

If the engine dies the battery charge light will come on. Having the charge light come on after the engine quits is not a definitive indication of a problem with the charging system. If the charge light comes on while the engine was running then that is likely a problem with the alternator or a bad electrical connection someplace. As Drew says, 14 V is good (probably around 14.4 V is where it should be). If the voltage stayed above 14 V and the charge light never came on while the engine was running the problem is not your alternator.

Like Drew, I am a bit confused by the statement "Motor cranked but did not turn". If that means that the starter motor was able to turn the engine over at its normal cranking speed; but, the motor failed to start then you do not have a battery or charging system problem. I suspect that you might have a bad electrical connection someplace.

The first place I would check is the battery terminals to make sure that they are securely clamping the battery posts. The NSX battery post clamps are notorious for being overtightened which stretches and tears the metal on the cable clamp so that they fail to securely grip the battery post leading to flakey electrical problems. Try twisting the cable clamps on the battery posts. If they move the clamps need to be replaced. Check to see if the clamps look deformed. If so, they need to be replaced. I swear that Honda makes their battery post clamps from recycled soup cans! If the battery post clamps are good, check the large connections at the engine compartment fuse box and the alternator.
 
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>noticed the engine did not rev when I blipped throttle while on neutral.

Sounds like a drive by wire issue.

>I noticed the battery light on the dashboard, so I safely cruised to a stop on the road shoulder. I turned ignition off, and tried to restart.

What was the reading on your voltage meter?

>Motor cranked but did not turn,

?? Cranking means the engine is turning...

> Battery had 50% charge after last night's 30 minute drive with 14v alternator reading

How did you determine 50% charge. Where is your battery charger hooked up to?

14V is good

**

as a wild guess based on what you have indicated. I suspect a high resistance short on the main battery wires.

Clean connections on each end of the wires and go from there...

Drew,

After I came to a stop, I tried to start. Engine did partial crank but failed to start. I waited and tried again but this time, only numerous successive clicking sounds were generated with flickering dashboard light (battery truly drained.) After a successful jumpstart, I drove for 30 minutes that night. The 50% battery charge reading with 14v alternator return was determined by AAA the following morning. He hooked up his handheld diagnostic to my batt terminals and had me turn on the ignition (car started strong like nothing happened the night before).
I forgot to mention that my pos/neg terminals had battery shims (half a shim per post, not the full thimble) to make a tighter fit. He made a comment that Hondas are notorious for having loose clamps after while and told me never to use these shims since they prevent full contact between clamp and terminal. Batt terminals are really clean with zero grime/buildup.

Wil
 
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First off, getting a new OEM alternator right now is essentially impossible. They are on back order everywhere. Over the counter rebuilds from places like Rock Auto are also impossible to find. If the alternator is the problem your only option will be to find a local rebuilder or do the work yourself. Its usually diodes, voltage regulator or brushes which are all quite doable by anybody handy with a wrench.

If the engine dies the battery charge light will come on. Having the charge light come on after the engine quits is not a definitive indication of a problem with the charging system. If the charge light comes on while the engine was running then that is likely a problem with the alternator or a bad electrical connection someplace. As Drew says, 14 V is good (probably around 14.4 V is where it should be). If the voltage stayed above 14 V and the charge light never came on while the engine was running the problem is not your alternator.

Like Drew, I am a bit confused by the statement "Motor cranked but did not turn". If that means that the starter motor was able to turn the engine over at its normal cranking speed; but, the motor failed to start then you do not have a battery or charging system problem. I suspect that you might have a bad electrical connection someplace.

The first place I would check is the battery terminals to make sure that they are securely clamping the battery posts. The NSX battery post clamps are notorious for being overtightened which stretches and tears the metal on the cable clamp so that they fail to securely grip the battery post leading to flakey electrical problems. Try twisting the cable clamps on the battery posts. If they move the clamps need to be replaced. Check to see if the clamps look deformed. If so, they need to be replaced. I swear that Honda makes their battery post clamps from recycled soup cans! If the battery post clamps are good, check the large connections at the engine compartment fuse box and the alternator.

Thanks OG. I did not notice whether the batt light came on while driving or after the engine stopped. I do remember blipping the throttle at neutral to downshift as I was slowing down anticipating traffic light to change by the time I'm close to it. When engine did not rev, that was when I noticed the battery light was on... the engine may have already been out.

AAA said the same thing about Honda clamps, they tend to loosen after a while plus he did not like the fact that I have half battery shims on each terminal post. He did say these may have contributed to the issue (but I thought, why now when they have been there for 8 yrs.?) He told me never to use shims, and just make sure the clamps are down all the way the thicker base.
Clamps are in pristine/clean condition without grime/buildup. He recommended for me to have the charging system tested at a shop. In the meantime, I will start looking for a reputable alternator rewinding shop if it may need to come to this.
 
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before going with a new alternator, i had read somewhere online that spray cleaning the alternator with some electrical cleaner and tapping it with a rubber mallet would help "revive" the alternator temporarily. This is what i used when my alternator went out before a drive from Sacramento to Los Angels. went from holding 9V at 4kRPM to normal 14V. its worth a shot and is only the cost of the cleaner.

This is the cleaner i used.
https://www.amazon.com/CRC-Industri...ronic+Cleaner+-11+Wt+Oz&qid=1631171966&sr=8-5
 
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I suggest a fairly simple test.

This is best done with a hand held voltmeter / multimeter set up to measure the voltage between the jump start terminal in the engine fuse box and the jump start ground terminal at the throttle body. You can do it using the dash voltmeter; but, the accuracy of the dash gauge is a little dodgy. Start up the engine and wait for the charging system to stabilize for about 5 minutes. Now measure the voltage. With no accessories switched on in the car the voltage should be in the 14.4 - 14.6 volt range. The alternator is rated at 120 amps output at 13.5 volts; but, that is with the engine spinning at 6000 RPM. At idle the alternator will not be capable of maintaining 13.5 volts at full output. Also, you don't have the ability to attach that much load. The actual load test in the service manual is at 85 amps which you also probably can't do. The best you can do is switch on the air conditioning (blower fan high), turn the headlights on (high beam), turn the radio on and switch on the four way flashers. I did this test on my car this morning (also a 2000 MYr) and at idle the voltage as measured on the jump start terminals with those loads switched on was 14.5 volts. If your voltage is significantly below that value then you likely have a charging system problem. That problem could be an alternator problem or it could be bad electrical connections between the alternator and the engine fuse box.

How many miles do you have on your car? If you are very high mileage (mine is something like 74 - 75,000 miles) the alternator brushes may be significantly worn and when that happens alternator performance can become erratic. Operates fine and then suffers from low voltage then fixes itself, wash - repeat. If the voltage in your test checks out fine, watch your dash voltmeter to see if it fluctuates while driving.

The ECU 'guts' operate at 5 volts provided by an on-board voltage control system so the ECU proper will continue to operate just fine with really low voltages. However, the peripherals take it on the chin. The injectors and the ignition coils operate at 12 volts and if the voltage takes a nose dive the injectors are slow to open which affects fuel delivery and the spark gets weak. The ECU has an algorithm in it which attempts to correct for low voltage to maintain injector and coil operation; but, that only goes so far and below 10 volts probably starts to fall off the edge of the world. The drive motor for the DBW throttle also appears to be supplied directly at 12 volts so it is possible that really low voltage could affect throttle operation in addition to ignition and fuel delivery problems
 
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Thanks Old Guy. Will do this test and see what comes up. Mileage at 64,232 mi. Looks like battery shims may have caused last week’s problem. Drove 23 miles today with a/c on, did hard acceleration all the way to 3rd at 6k and she was strong and steady. Watched dash gauges, all systems good. Last week may have been a fluke.
Thanks for all y’all’s advice. Will keep you posted how this plays out.
 
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I suggest a fairly simple test.

This is best done with a hand held voltmeter / multimeter set up to measure the voltage between the jump start terminal in the engine fuse box and the jump start ground terminal at the throttle body. You can do it using the dash voltmeter; but, the accuracy of the dash gauge is a little dodgy. Start up the engine and wait for the charging system to stabilize for about 5 minutes. Now measure the voltage. With no accessories switched on in the car the voltage should be in the 14.4 - 14.6 volt range. The alternator is rated at 120 amps output at 13.5 volts; but, that is with the engine spinning at 6000 RPM. At idle the alternator will not be capable of maintaining 13.5 volts at full output. Also, you don't have the ability to attach that much load. The actual load test in the service manual is at 85 amps which you also probably can't do. The best you can do is switch on the air conditioning (blower fan high), turn the headlights on (high beam), turn the radio on and switch on the four way flashers. I did this test on my car this morning (also a 2000 MYr) and at idle the voltage as measured on the jump start terminals with those loads switched on was 14.5 volts. If your voltage is significantly below that value then you likely have a charging system problem. That problem could be an alternator problem or it could be bad electrical connections between the alternator and the engine fuse box.

How many miles do you have on your car? If you are very high mileage (mine is something like 74 - 75,000 miles) the alternator brushes may be significantly worn and when that happens alternator performance can become erratic. Operates fine and then suffers from low voltage then fixes itself, wash - repeat. If the voltage in your test checks out fine, watch your dash voltmeter to see if it fluctuates while driving.

The ECU 'guts' operate at 5 volts provided by an on-board voltage control system so the ECU proper will continue to operate just fine with really low voltages. However, the peripherals take it on the chin. The injectors and the ignition coils operate at 12 volts and if the voltage takes a nose dive the injectors are slow to open which affects fuel delivery and the spark gets weak. The ECU has an algorithm in it which attempts to correct for low voltage to maintain injector and coil operation; but, that only goes so far and below 10 volts probably starts to fall off the edge of the world. The drive motor for the DBW throttle also appears to be supplied directly at 12 volts so it is possible that really low voltage could affect throttle operation in addition to ignition and fuel delivery problems


Update: Did this recommendation. Five minute idle, a/c on with fan high, headlights on hi-beam, radio on, hazard lights flashing for five minutes, then drove for a total of 20 miles with the battery meter at a hairline over 14v all the time. No problems today, and hopefully not any for a long time. Thanks again.
 
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