Hi, All!

Long story short...

Got stranded at a filling station last night. '91 Nissan King Cab truck woudn't start. Did finally get it to start.

Drove to an auto parts store. Thought that I might need a new battery. Worker there checked the battery. Battery was drained. He then checked the alternator after jump starting my truck. Said that it was only putting out 30 amps when it should have been putting out 90 amps.

Ended up getting a new battery because the battery was so old. Probably need to get a new or used alternator.

At 30 amps, is the alternator charging up the battery at all?

Thanks!

IF it has enough charging voltage... and IF the current loads are LESS than 30 amps total it should charge... how fast depends on the differences between the output and the load. BUT with that said... you aren't always operating the engine at the point that the alternator has max output... its not a flat line across all RPM's, but an uphill slope where you would likely has a load that excedes the charging current at lower RPM's which will drain the battery. I'll bet this is what's happening in your case. 30 amps isn't much... not if you have the lights and or stero running. Wiithout sitting down and doing some math... I'll guess that's insufficient for most situations.

You should replace that alternator based on those test results

This link below should help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1973613

If the regulated battery voltage is between 14 and 15 volts, the alternator should be fine.

Clough, besides letting you down last night, how'ya like that nissan, I'm on my second, and just love them. I had over 250,000 when I sold the 88 and I'm driving a 97 now with a little over 200,000 miles. Good luck with yours

Forgot to say, only problem I've had with mine was the starter, just put one on the 97 and think I put two on the 88. So don't overlook that.

At 30 amps, is the alternator charging up the battery at all?

Yes. The alternator is likely only putting out 30 amps, because that's all the loading requirements are. Continue testing the regulated battery voltage, but start loading the system down. Have another person turn on the head lights (10 amps), A/C (30 amps), rear defroster (15 amps), and so forth. While this is being done, the regulated battery voltage should start to drop towards 12.5 volts. This gives you a better picture of how the charging system is supposed to function under load. As the loading progresses, it will give you an idea of how much amperage your alternator can produce. Remember, alternators are designed to produce maximum amperage for only brief periods.

Thanks for all of the replies!

The guy at the auto parts store tested the alternator with just me starting the engine. Nothing else was turned on.

So, if I understand correctely, the alternator only puts out the amps that it needs to put out, based upon the load requiements that are happening?

Thanks!

clough, besides letting you down last night, how'ya like that nissan, I'm on my second, and just love them. I had over 250,000 when I sold the 88 and I'm driving a 97 now with a little over 200,000 miles. good luck with yours

Hi, parttime!

I love the truck, but not in the wintertime when there's so much snow here! It's really light weight, and my tires are not in the best of shape.

Thanks!

Exactly. In practice, here's a little more on how the charging system works:

The alternator FR (Field Response) signal communicates to the ECM how "hard" the alternator is working to meet the electrical demands of the car, including the battery and any loads which aren't monitored by the ELD. This square-wave signal varies in pulse width, according to the load on the alternator. The ECM places, approximately, 5 reference volts on the wire. The voltage regulator will drop this signal to approximately 1.2 volts, in proportion to alternator load. The ECM compares the electrical load (ELD) signal with the FR (Charging Rate) signal from the alternator and uses that information to set the idle speed and turn the alternator on and off. This helps fuel economy. Higher alternator amperage comes at a cost.

If you had an ammeter installed in your car, the needle would be at "0," if everything was normal. If the alternator wasn't able to balance everything out, the scale might show a discharge of -5, -10, or -20 amps. Conversely, if the alternator was charging a lot, the needle might show +5, +10, or +20 amps. Alternator amperage output is a function of load; i.e. it would be foolish to have it provide maximum amperage all the time. It wouldn't last long. Most people don't think about this, but an alternator's rpm is probably 6 times engine rpm. Finally, ammeters show the charging system's status (flow) real time, unlike voltmeters (pressure).

You're getting over my head here, TxGreaseMonkey!

What do the acronyms stand for that you haven't already explained, please?

Thanks!

ECM--Engine Control Module (or computer)
ELD--Electrical Load
FR--Field Response (charging rate)

Glad you asked your question. Many others will learn a lot about alternators from it.

Let me know the results of your tests. I bet the alternator is fine and the problem resided only with the battery.

Let me know the results of your tests. I bet the alternator is fine and the problem resided only with the battery.

Do you really think so? The battery was really old, though...

This truck doesn't have all that many miles on it, although it's a 1991.

The people who I purchased it from, only used it for gardening stuff and to haul the dogs around.

Thanks!

Yes.

Well, tonight the truck "died". Won't start at all. Barely got it across one of the bridges over the Mississippi. Managed to park it in the parking lot of a Quick Mart type of store.

Need to now have it towed to a service station and see what's going on.

The symptoms were, losing power, decrease of any lighting, hesitation and what I would guess I'd call lack of any acceleration power when pressing on the accelerator pedal.

I now have none of my own transportation, so this is definitely an issue with which I need to deal!

Just got a couple of new tires for the truck as well as the new battery.

Money is incredibly tight!

Advice, please?

Thanks!

Is your truck a 2WD and do you have the 4-cylinder engine?

Perform tests in the link below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-11.html#post2123675

What were the results of the regulated battery voltage test the other day? Do you believe the alternator is at the heart of your problem?

It's a two wheel drive. It's also a four-cylinder engine.

The results of the battery test was that it was drained. Yes, I believe the alternator is at the heart of the problem.

I did just have it towed to a service station, though. No other choices for what to do.

I'll let you know the outcome.

Thanks!

You may want to have the mechanic check to see what the parasitic power drain level is... basically with everything turned off. You will laways have some on any newer vehicle... whats key is how much.

It IS possible for the battery to drain overnight even with a perfectly good alternator... just that the alternator is the most likely point of failure.

Is your truck a 2WD and do you have the 4-cylinder engine?

Perform tests in the link below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-11.html#post2123675

What were the results of the regulated battery voltage test the other day? Do you believe the alternator is at the heart of your problem?

By the way, there's some great information on the thread for which you provided a link! :)

Thanks!

You may want to have the mechanic check to see what the parasitic power drain level is... basically with everything turned off. You will always have some on any newer vehicle... what's key is how much.

It IS possible for the battery to drain overnight even with a perfectly good alternator... just that the alternator is the most likely point of failure.


parasitic power drain level What is that, please?

Thanks!

parasitic power drain level

In the home it's called fantom power or the power drain that happens when "nothing" is aparently running like parked in the driveway with everything off.

A very small amount of electricity is used to keep your radio presets, and allow the clock to keep time and to save some computeed parameters for driveability into the computer.

After the battery is disconneted, it should take a few "driving cycles" to learnt he paremters for the engine. During this time the engine may have driveability problems, although not severe. A "driving cycle" is manufacturer dependent. Usually it contains a few cold starts and some amout of time driving at a steady speed at operating temperature.

Yes, the battery discharges a small amount by sitting too.

What is that, please?

Thanks!
What that is... basically is what the current draw is from the battery with everything turned off. With the radio... ECU, clock... there will always be a very small amount, it won't be zero. But that amount SHOULD be low. It shouldn't effect the vehicle unless it sits a few months in summer, maybe a month in winter without being started and charged. Not sure of a good ballpark number but its likely the low milliamp range. Its really not hard to check... just an ammeter between either cable and that battery post with everything off. Anything approaching an amp or even more is a real problem and would need isolation.

Here's my two-cents on parasitic battery drain:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post241804

Had the truck towed to the service station, today. They charged the battery and said that the alternator was fine. One of them even drove the truck around for awhile.

I took it tonight, the auto parts store again. Someone else checked it out, much more thoroughly than the last person at the same store did.

Turns out that it's the alternator bearing. It's not always spinning(?) correctly to produce enough of a charge.

Clough, I'm curious what the total cost of this repair was? If you don't care. Thanks

Had the truck towed to the service station, today. They charged the battery and said that the alternator was fine. One of them even drove the truck around for awhile.

I took it tonight, the the auto parts store again. Someone else checked it out, much more throughly than the last person at the same store did.

Turns out that it's the alternator bearing. It's not always spinning(?) correctly to produce enough of a charge.
That explanation doesn't sound right at all. If the bearings were bad its going to make a hell of a racket at worst, or feel rough as you spin it by hand at least... unless its seized up forcing the belt to slip its going to spin (the alternator) its normal RPM's.

Clough, I'm curious what the total cost of this repair was? if you don't care. Thanks

Hi, parttime!

I don't mind sharing this at all!

The total cost for towing and looking over my truck, charging the battery, adding some gas and brake fluid and driving it around, came to $74.00 something.

I think that they were giving me a break though, because they were unable to find the real problem. Plus, I know them and taught some of the kids in school.

There is no charge at the auto parts store when they install something that I've purchased from them.

Thanks!

What exactly did they install?

Originally Posted by Clough https://www.askmehelpdesk.com/images/buttons/viewpost.gif (https://www.askmehelpdesk.com/cars-trucks/alternator-only-putting-out-30-amps-charging-battery-all-446326-3.html#post2231087)
Had the truck towed to the service station, today. They charged the battery and said that the alternator was fine. One of them even drove the truck around for awhile.

I took it tonight, the the auto parts store again. Someone else checked it out, much more throughly than the last person at the same store did.

Turns out that it's the alternator bearing. It's not always spinning(?) correctly to produce enough of a charge.

That explanation doesn't sound right at all. If the bearings were bad its going to make a hell of a racket at worst, or feel rough as you spin it by hand at least... unless its seized up forcing the belt to slip its going to spin (the alternator) its normal RPM's.

Hi, smoothy!

There's only one bearing in this particular type of alternator. It does make one heck of a racket while I'm driving!

Thanks!

Clough, I've use this link HB Truck - Nissan Forums: Nissan Forum (http://www.nissanforums.com/hb-truck/) for years,it has really knowledgeable nissan truck people, good place for info. I hope your fixed up now.

All alternators have a front and rear bearings. Your Nissan alternator has an Alternator Drive End Bearing (Timken 303CC) and an Alternator Commutator End Bearing (National 201CC). The front drive end bearing tends to go first, because of the belt load. Alternator rpm is approximately 6 times engine rpm.

New problem...

New alternator has been installed. Also have a new battery. All connections are secure and clean.

Battery continues to be drained.

Ideas anyone, please?

Thanks!

See if this link offers any help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-3.html#post241804

Clough, does the battery die just sitting around, like overnight? You may have a ground somewhere, has there been a radio or cd player installed? I once had similar problem, by pulling fuses one at a time, was able to detrime the bad circuit and was able to find ground and repaired with tape. Good luck

To add to TX's link.
I like to start with a charged battery, read the voltage, start the vehicle. Verify it increases.
3 most common things, is a bad battery, an alternator that is not charging, or a drain.
If battery and alternator are working correctly, it is likely a Drain, and I would as do as TK's
Link mentions, place a bulb between Negative post and negative cable. With no draw, the bulb will not light. It will likely light due to electronics needing a constant feed.
I like my Clamp on ampprobe, clip it around the cable, and it show amps drawn. Remove each fuse to determine the culprit(s).
Quick note about the DC amprobe, it will work on the positive or negative cable, after you clamp on, zero it, open the door, or turn on the lights, it should read a negative number, if it reads positive, unclip and reconnect 180 degrees, now the numbers shoul d read negative.
If it is running it should show a positive amps.
Just because a manufacturer says it is a AC/DC amprobe, many only do AC Amps, but do DC volts as well, a little missleading.
I would check your Main ground on Block/Starter?

clough, does the battery die just sitting around, like overnight? You may have a ground somewhere, has there been a radio or cd player installed? I once had similiar problem, by pulling fuses one at a time, was able to detrime the bad circuit and was able to find ground and repaired with tape. good luck

I don't really know if the battery dies when my truck isn't running. No electronics are on in the truck, other than when the inside overhead light is on.

What do you mean by repairing with tape, please?

Thanks!

To add to TX's link.
I like to start with a charged battery, read the voltage, start the vehicle. Verify it increases.
3 most common things, is a bad battery, an alternator that is not charging, or a drain.
If battery and alternator are working correctly, it is likely a Drain, and I would as do as TK's
link mentions, place a bulb between Negative post and negative cable. with no draw, the bulb will not light. It will likely light due to electronics needing a constant feed.
I like my Clamp on ampprobe, clip it around the cable, and it show amps drawn. Remove each fuse to determine the culprit(s).
Quick note about the DC amprobe, it will work on the positive or negative cable, after you clamp on, zero it, open the door, or turn on the lights, it should read a negative number, if it reads positive, unclip and reconnect 180 degrees, now the numbers shoul d read negative.
If it is running it should show a positive amps.
Just because a manufacturer says it is a AC/DC amprobe, many only do AC Amps, but do DC volts as well, a little missleading.
I would check your Main ground on Block/Starter?

If I were to go out and buy the testing light, what specifically would it be called, please?

With getting into all of the technical terms, I'm getting a bit over my head here!

Thanks!

What do you mean by repairing with tape, please?


I found a bad place in a wire and taped over it to prevent it touching metal and draining her battery,(like leaving a dome light on). That was after the local radio shack installed a new cd player, they didn't do a very professional job. Clough, I take it you don't normally do your own repairs?

What do you mean by repairing with tape, please?


I found a bad place in a wire and taped over it to prevent it touching metal and draining her battery,(like leaving a dome light on). that was after the local radio shack installed a new cd player, they didn't do a very professional job. Clough, I take it you don't normally do your own repairs?

I normally do all of the repairs that I can that aren't unusual. This would seem to be unusual in that I've already "covered the bases" so to speak with replacing the battery as well as the alternator.

Any and all advice is much appreciated! If it were a piano or other type of musical instrument, I could fix it! Cars and trucks? Really very much out of my league these days! Back in the 1970's, tuning them up was no problem! These days, it's really hard to know what I'm doing with them...

Thanks!

A problem like yours can have good mechanics pulling their hair out. Good luck

I'm still waiting for Stratmando to answer my question as to what specifically to call the testing light.

I will be patient and I appreciate it with those who are knowledgeable about such things for ignoring my ignorance!

Thanks!

You could buy any 12/24 volt test light to do the job, all auto parts stores and most big box stores carry them.

Would K-Mart or Menards have something like that? They're just down the street from here.

Thanks!

Yes, more than likely, if you Google 12volt test light you can see what they look like.

The first place where I had the new alternator installed, well they put it on bass awkward! Got stranded a couple more times! Belt was rubbing against an adjusting bolt!

Decided not to even go back to them to have them correct the problem. Smelled booze and pot at the end of the day at that place.

Not good...

Asked a Pastor at one of the churches where I go to help me. Got it towed. Am very pleased with the work done at the import place to where it was towed.

First place also wanted twice as much for a new air filter.

So far, so smooth...

Thanks!

Clough:

Do you own a digital voltmeter?

Clough:

Do you own a digital voltmeter?Yeah.. those can bre really cheap. Harbor Freight has them on sale for 3 or 4 dollars every so often. Less than a replacement 9 volt battery inside would cost. So its not a big investment to have in the house.

Sorry Clough, wasn't aware of your response,A year or more ago I tried to eleminate being sent emails for every response to a post, I unchecked everything I coud to eleminate them, I still get the Mail, but they don't always show up when I click "My Profile", A real pain, but I live with it.
How to Use a Test Light (http://www.2carpros.com/dia/test_light.htm)
Here is a DC Amprobe, I got mine years ago for under $100 I believe, this one is over $300, but this link does have the instructions which is useful knowlege:
http://www.testequipmentdepot.com/amprobe/clampmeters/lh41a.htm

Okay, don't have a Harbor Freight store around here.

Any other types of stores that might have a digital voltmeter that's inexpensive, please?

Thanks!

Check HarborFreight.com.