Alternator Charging Well But Not Charging When Demand Is High

[epic1400cs]

I am having charging issue last couple of weeks. I have searched through many thread and gave me good idea how to approach the problem but I still can't pin point partially because I have no idea about car electrics.

The problem started when my wife tried to start my Aerodeck (A20A4, Injection, identical to A30A3 except A20A4 has no cat), battery was dead. I quickly charged up the Red Top Optima with battery charger and after 5 mins, it managed to clank the motor and was ok.

Next day when I drove, it started ok but now showing charging warning light on dash board. It was not constant, intermittent but somehow I managed to drove 20min to my son's school, stop the motor, managed to start again and came home.

I removed and charged up the Optima with main fed battery charger and it says fully charged. I drop it back to car and started ok. I test drove around town include slow traffic and 60m/h fast traffic about 30 min with using no electric accessories like heater or light and came back. Check with electric tester on the battery terminal, the reading was 14.5V while the motor is running. As a test, keep the motor running and turned head lights, rear defogger, heater blower full and the voltage reading is going down like hell, like counting down. When it went under 12V in may be 10 second, I turned accessories off, then the reading went back to 14.5V again.

I was assuming by this time that alternator is charging but when the load is high, it can't supply enough. So as a last test, I turn heater blower at lowest, wiper on, small light on then I drove around for 30min, no problem, reading was 14.5V when motor is running, when stop, the tester reading of the battery is about 12.5V. There was not charging warning light.

What do you guys think, whats wrong with the alternator? Rectifier? Diode?(even I don't know where they are).

The trouble alternator is refurbished unit by Lucas UK about 10 years ago and I bought it as old stock brand new refurbished on ebay recently and installed it about a month ago(call it no.4) Originally it was for carb, I opened it and I have changed the rectifier (the board with 3 or 4 pin connector) from my old Denso alternator(call it no.1). This old alternator(no.1) was working fine when I removed it 4 years ago. I swapped no.1 with refurbished one (call it no.2)'just in case' if the original one (no.1) was at its limit before our long trip (when I look back now I should have left it, I know!) The no.2 has died after one month on out trip to Netherland (ouch!) and I have no choice than buying questionable refurbished one (call it no.3) in Amsterdam. This €480 no.3 has been working but the bearing was making grinding noise badly so I decided to change to no.4.

The optima battery is 4 years old and it had flat only one time because my son has left room lamp on over night Apart from this red top has been working wonderful.

Any suggestion is welcome.

[w261w261]

"Refurbished" alternators are such a ripoff. I think most of the time they throw a new set of brushes in, clean up the outside, and send them off. Maybe they work, maybe they don't, but it's cheaper to just send out another p.o.s. and let the customer pay the labor to try again.

[lostforawhile]

it sounds like the brushes are bad or the voltage regulator.

[ecogabriel]

"Refurbished" alternators are such a ripoff. I think most of the time they throw a new set of brushes in, clean up the outside, and send them off. Maybe they work, maybe they don't, but it's cheaper to just send out another p.o.s. and let the customer pay the labor to try again.

The "honda refurbished" that came with my car just died, and those were supposed to be better than anything else.
I've had alternators dying on me before but they were diodes or bearings; this is the first one that got its windings getting fried before my eyes.

[lostforawhile]

I've had really good luck with the Nappa ones, the one I'm sending you is a Nappa rebuild, it was working fine when I parked the car. It's a long story how i ended up with a good running rebuild, and a brand new one at the same time.

[ecogabriel]

I've had really good luck with the Nappa ones, the one I'm sending you is a Nappa rebuild, it was working fine when I parked the car. It's a long story how i ended up with a good running rebuild, and a brand new one at the same time.

I thought you got a new alt to get enough power for all the electronics you are installing.
I don't know about NAPA rebuilts but I'll find out soon thanks to you .

[epic1400cs]

"Refurbished" alternators are such a ripoff. I think most of the time they throw a new set of brushes in, clean up the outside, and send them off. Maybe they work, maybe they don't, but it's cheaper to just send out another p.o.s. and let the customer pay the labor to try again.

My experience above back up your statement.

it sounds like the brushes are bad or the voltage regulator.

When I opened the back of this no.4 alternator, I have checked the brushes and they were new and looked ok (I have checked the length). But could be stuck some how. Can you give me a hint why do you think it can be voltage regulator? I might be able to swap regulator from no.3 refurbished one (making noise but were charging ok). Or can you point me any good link/reference to read?

[lostforawhile]

My experience above back up your statement.



When I opened the back of this no.4 alternator, I have checked the brushes and they were new and looked ok (I have checked the length). But could be stuck some how. Can you give me a hint why do you think it can be voltage regulator? I might be able to swap regulator from no.3 refurbished one (making noise but were charging ok). Or can you point me any good link/reference to read?

just change it and see how it does, it's more then likely the problem

[epic1400cs]

just change it and see how it does, it's more then likely the problem

Assuming you are pointing regulator, I have found a link that makes sense to me



The regulator is the brain of the charging system.
It monitors both battery and stator voltages and depending on the measured voltages, the regulator will adjust the amount of rotor field current to control alternator output.

(http://www.autoshop101.com/trainmodu...or/alt101.html)

This page is using Denso alternator as if specially for us

It make sense because if regulator is bad then it doesn't 'measure battery voltages' nor 'adjust the amount of rotor field current'.
I will try to swap regulator tomorrow if the weather is good.

[epic1400cs]

Today is good weather here in UK so I decided to have a go at it. As this is my 5th time to remove alternator, I became pretty quick doing it (compare to my first time took half day to just remove it!). Remove air cleaner box(mine is injection), remove bottom nut of alternator from tire house then remove alternator from the space where air cleaner was then it was about 30 min.

Anyway, I fit the regulator from no.3 refurbished in Amsterdam and put them back again. The test went as below.

1) Engine idling with no load - tester reading at battery posts was 14.58V
2) Engine idling with rear defogger on - 14.52V
3) Engine idling with rear defogger and heater blower on - 14.5V
4) Engine idling with rear defogger, heater blower and head lights on then suddenly the voltage went down but it stopped around 12.5V more or less and it never go below 12.4V

During this test there was no charging light on. When I start the motor, key at on position then charging light stays on, when motor started, it went off.

I feel it is ok now but one thing I am not sure is why 2) and 3) didn't draw much voltage but suddenly in 4) it start drawing a lot. I will keep eye on it.

[Oldblueaccord]

You are correct in checking your voltages but your missing testing your amperage output. That will give you more information on how well your alternator is working.


wp

[epic1400cs]

You are correct in checking your voltages but your missing testing your amperage output. That will give you more information on how well your alternator is working.
wp

Thanks for pointing that out! I will check later today if possible.

[AccordEpicenter]

Im with lost, bad brushes or regulator

[lostforawhile]

Thanks for pointing that out! I will check later today if possible.

one thing you can do is turn on the accessories such as the lights and heater blower, etc, the measure voltage , it should be around 14 volts or just a little less, you are loading the system by doing that.

[knarg]

Bumping this thread, having a similar problem to that described in original poster's last post.

I have replaced the alternator twice with Autozone/Duralast replacements and the battery as well. The voltage reading at the battery is fine with all accessories off, ~14V but drops to 12.8V when under the load of the headlights and heater on full blast.

Could this be caused by bad ground straps or something other than the alternator/voltage regulator?

[gp02a0083]

i doubt it would be a ground strap, not to say that could be the issue here. After reading some of the past posts it seems like the alternator is working fine at idle. Ok so it is charging, regardless of what you have running on the stock system (no sub amps and stuff like that) should be above 14V, with all the accessories on I believe it should task the electrical system and the current draw would be different.

i would agree with Lost on this one , the regulator could be shot or on its way out. Do you notice any power loss when driving the car at higher rpm's? other than that you could have a short somewhere in the lighting system causing a drop in voltage.

i also came up with one thing to look at. You mentioned the height of the brushes in the alt were ok, did you look at the faces of the brushes that come in contact with the communitator ? I have had experience with electric motors when the com's surface is uneven causing intermittent or general loss in power.


it also could be that the battery is that far gone, when the system is working and charging , the battery is storing and using the charge from the Alt. If the battery is dead and cannot hold a potential, then you would be running only on the supply from the alternator.

if any of this is wrong , someone correct me

[Oldblueaccord]

Again amp draw.

Possible the heater blower is drawing a large amount of current(amps). I have had trouble with mine its going bad pullling more than 20 amps (blowing a 20 amp fuse).Its factory fused for like 40 amps from an underhood fuse I believe. I added an inline fuse after I replaced the over heated stock connector.

So running headlights,fan you might be pulling 40 amps. With a stock alt that prolly over its capacity at idle speed.

wp

[import racer]

Did you charge your bat through another bat or just the one,I read somewhere you have to charge an optima battery though another 12 volt bat or it won't charge properly .Maybe thats your problem.

[88lxi-shortram]

i just finished the charging section of my class and im going with regulator problems.

[lostforawhile]

Bumping this thread, having a similar problem to that described in original poster's last post.

I have replaced the alternator twice with Autozone/Duralast replacements and the battery as well. The voltage reading at the battery is fine with all accessories off, ~14V but drops to 12.8V when under the load of the headlights and heater on full blast.

Could this be caused by bad ground straps or something other than the alternator/voltage regulator?

the problem is where you bought the alternator, their products are crap, even if they work they will fail soon, after going through a bunch of alternators from there, and three bad starters in a row, all bad out of the box, one, parts fell out as I was removing it from the box, I now use Nappa stuff, haven't had a problem since, make sure you use the top end brand stuff from there, there are two lines, one is the cheaper one, and one is the best quality. Good electrical parts aren't cheap,despite what the discount chains try to say

[Hauntd ca3]

nippon denso regs dont usually give up unless there is some thing else wrong elsewhere.
when they pack up they either wont charge or will over charge somewhere round 17 volts
since the voltage isnt dropping off until you have quite a load on the charge system if going to say the brushes are getting down.
if you've had the back off the alt, have a look at the slip rings tat the brushes run on.they should be the same colour as the brushes but have no sign of any arcing which shows up as a slightly rough feel or look.
if you see that rough bit, put new brushes in it and give the slip rings a sand with some 400 grit paper.
also, check the voltage with all the acc,ie light,heater and demister on but rev the engine to around 2500rpm.
at idle the alt just isnt spinning fast enough to charge at a decent rate.
you would find that the voltage will come up quite a bit.
also, altenators are not designed to charge a battery from nearly flat.
they are only to top up a battery and keep up with the drain of the acc load.
trying to charge a battery from near flat to many times will cause the alt to overheat and it will die a horrible electrical death.

[2oodoor]

nippon denso regs dont usually give up unless there is some thing else wrong elsewhere.
When they pack up they either wont charge or will over charge somewhere round 17 volts
since the voltage isnt dropping off until you have quite a load on the charge system if going to say the brushes are getting down.
If you've had the back off the alt, have a look at the slip rings tat the brushes run on.they should be the same colour as the brushes but have no sign of any arcing which shows up as a slightly rough feel or look.
If you see that rough bit, put new brushes in it and give the slip rings a sand with some 400 grit paper.
Also, check the voltage with all the acc,ie light,heater and demister on but rev the engine to around 2500rpm.
At idle the alt just isnt spinning fast enough to charge at a decent rate.
You would find that the voltage will come up quite a bit.
Also, altenators are not designed to charge a battery from nearly flat.
They are only to top up a battery and keep up with the drain of the acc load.
Trying to charge a battery from near flat to many times will cause the alt to overheat and it will die a horrible electrical death.

^^^this

[knarg]

the problem is where you bought the alternator, their products are crap, even if they work they will fail soon, after going through a bunch of alternators from there, and three bad starters in a row, all bad out of the box, one, parts fell out as I was removing it from the box, I now use Nappa stuff, haven't had a problem since, make sure you use the top end brand stuff from there, there are two lines, one is the cheaper one, and one is the best quality. Good electrical parts aren't cheap,despite what the discount chains try to say

my last alternator definitely had a bad voltage regulator, but my current alternator reads more reasonably and passes the autozone diagnostic tool load testing. i think to generalize all their products as crap is naive, and though conceivable, it is unlikely that my current voltage regulator is not working.

nonetheless, my voltage is not being regulated properly--but i think this is caused by some other problem. i suspected the belt may be bad, or too loose/tight, but it seems fine.

i also have no battery light or check engine light, and the car runs fine. no problems with power, etc.

[knarg]

what testing can i do to isolate the voltage regulator or alternator as the problem?

[Dr_Snooz]

i think to generalize all their products as crap is naive

When one of their alternators has left you stranded at a rest stop hundreds of miles from home and you have to get a very expensive tow to the nearest store and then buy tools and replace it in the dark with a crappy Chinese flashlight clenched in your teeth, pausing regularly to wipe the drool off of it, you tend to see things in a more black and white way.