Alternator not charging? or Overcharging?

[sergitin32]

Hello, I was looking through other threads but didn't find anything like this so I started my new topic.

CAR: 1989 Volvo 240 DL sedan, 317XXX km, LH 2.4, all stock engine and electric wise.

So a week or so back I realized the battery light was on but it was kinda very dim, like not on for real. It was night and I blame it to maybe be catching a glimpse of another close by light, like the light bulb thingy that is always on since I put a 4 square lights front end and since then that light came on, but I am OK with it. Also since I don't drive much at night maybe this was what it looks like, but still suspected something was going on. My mistake not to be more proactive.

Yesterday on my way to the gas station almost empty of gas it died, I guessed it was just off fuel, but then before dying it did a bunch of electric gremlins like the Tach went flat down even with the engine going, then died. I push it and it made it to the pump, fill it up and try starting, no way. Cold dead. My battery is almost new, maybe 4 months on it. Its winter and I am biking to work so I haven't driven much lately, but still not like the car is always sitting, I do drive like a couple times a week. I did get a gentle soul to help me out and give me a jump start, then on my way home, knowing this was not good, it started going nuts, stalling and Tach and speedo all over the map, made it to the top of the hill yeah!!! downhill driving it completely dead with the e-brake engaged to control speed and hard turning the steering but, sure enough, ended up barely pushing it into my underground parking spot and gave it a high 5 for taking me there even been so sick: MY CAR ROCKS! I just think its jealous from the 1992 Volvo Station Wagon I got recently, so it's acting up, just looking for attention.

Reading in forums around the network I discovered that when the battery charging light is on but just slightly dim means the alternator is overcharging and sending extra current and a higher voltage back through the exciter wire into the light, so the flow of the current would be contrary to the usual.

This car comes with a Bosch 80 AMP alternator but I have handy from a previous 1983 DL another Bosch but 55 AMP one, I am wondering if I don't use the heated seats and since there is no air conditioner, could I just use this smaller output alternator? Or at least it's voltage regulator if it comes to be the culprit?

Also besides doing the regular check-ups for ground for the alternator, continuity for the exciting wire, and continuity for everything I can check; How can I know the trouble is in the alternator itself and not the Voltage regulator attached to it?

When I came upstairs the Voltmeter showed 11.24 Volts in the battery. That worries me a lot since I know this could get the battery in trouble. So I put it to charge at 2 AMP low and steady for about 24 hours >> now: 12.23 Volts, I was hoping for more, but I think this is OK. What do you think? I will leave it there for another day or so and then keep it with a battery tender that would do just 0.9 AMP or so till I am ready to put it back in there.

Luckily for me, I think, I do have that other Volvo 240 with a good battery (some other issues), I could use this one for diagnosing the issues with my '89.

This is what I have in mind to get done for now.
- Put the good battery in there.
- Check for 12V in exciter wire when the ignition switch is ON.
- Check for belt tension and condition, change belt if needed.
- Check the grounds for the alternator and connections to battery etc.
- Check for continuity in all the wiring around this unit where possible.
- Turn the car on for a test and measure the voltage at battery terminals. There should be around 14 Volts, right? At what RPMs?

If things don't look good, I wonder how could I start looking for a bad regulator? I guess if the voltage is constantly at over 14.5 Volts or so I would blame the regulator? Is there anything physically that I can look for in a worn down regulator? I think they have brushes? Can I exchange brushes from the older 55 AMP unit if they are done?
Ask again: Can I put on the regulator from a Volvo 1983 Bosch 55 AMP alternator?
Can I just put the hole 55 AMP unit in or should I fear to starve the ECU or EZK if I do so?

Next step if nothing helps would be going to e-Bay and getting an 80 or 100 AMP unit to substitute this.
But it would be good if I can fix it with whats in hand and save the dough.

Thanks for any information you could share and hope you have a great 2018.

Sergitin.

[RickHaleParker]

" slightly dim means the alternator is overcharging"

If it was overcharging, you would not of ran out of electrical power on the way home. The alternator would of keep the engine running.

This is what I have in mind to get done for now.
- Put the good battery in there.
- Check for 12V in exciter wire when the ignition switch is ON.
- Check for belt tension and condition, change belt if needed.
- Check the grounds for the alternator and connections to battery etc.
- Check for continuity in all the wiring around this unit where possible.
- Turn the car on for a test and measure the voltage at battery terminals.

Good start, but clean all the connections on the charging system that includes all the connections to the alternator.

There should be around 14 Volts, right? At what RPMs?

The voltage depends more on the batteries's State Of Charge (SOC) then the engine RPMs.

I think they have brushes?

Alternators can have brushes not regulators. If the alternator is defective get a remanufactured one.

So I put it to charge at 2 AMP low and steady for about 24 hours >> now: 12.23 Volts

What is the battery size and how old is it?

[sergitin32]

Thanks for the response Rick
The battery is about 4 months old. Size meaning its dimensions or its power?
It is a Motomaster (010-9100-4 part number) with 860 Cold Crank Amps at Cero Celcius.

I do remember in most charging systems check out voltage is associated with RPMs, I guess they assume the battery is in optimal charged conditions? Assuming that the battery SOC is good, like 12.5 Volts in a 4 months old battery, at what RPMs would you be testing the alternator output? ie: Idle at 800 RPMs or a little more? I would think there is a chart where the voltage of the alternator goes up with RPMs till it hits 14 Volts or kinda?

Sorry, maybe I didn't express my idea correctly, meaning the voltage regulator has the brushes for the alternator to work, as it is all in the same ensemble. The maximum wear is when the brushes are 7mm long, or short should I say. So tomorrow I will also check the length of these. It seems like at least brushes are interchangeable so I might try using the ones from my older alternator if these are worn out.

Thanks for your response again, cheers.

Sergitin32.

[RickHaleParker]

It is a Motomaster (010-9100-4 part number) with 860 Cold Crank Amps at Cero Celcius.

I was looking for the Ah rating to get an idea how long it would take for a 2A charger to bring the battery up from completely depleted to 100% State of Charge (SoC) if, it can be brought back up.

You depleted that battery real deep, like deep freeze deep and it is four year old so it may not recover. The Motomaster 010-9100 is a 58 Ah battery. Under ideal condition, a 2A charger would take it from 0% SoC to 100% SoC in 29 hours. Your condition is no where near ideal. Your looking at 48 - 72+ hours if it can be done.

For a discharged battery 14V to as high as 15V is not an issue. It is when a battery approaches 100% SoC that higher voltages become a problem. Don't worry about it, nowadays even a low cost charger has enough artificial intelligence to know when to ramp down the voltage. So does a Voltage Regulator.

I would think there is a chart where the voltage of the alternator goes up with RPMs till it hits 14 Volts or kinda?

A chart like that would be nonsense, the voltage regulator does exactly what it's name implies. It regulates the voltage to protect the battery and the alternator.

the voltage regulator has the brushes

Once again, brushes are part of the alternator not the regulator.

[sergitin32]

OK, the battery is 4 MONTHS old as in 120 days old, as in almost brand new. Wrote that info triple times in my 2 last posts.
This is the first time this happens, I know it's not ideal but I believe it can recover from this time only.
As per now, the battery is at 12.35 Volts so it's looking good. and I will leave it in a trickle for a few more days just to treat it fairly.

The chart was a hypothetical thought, I know the voltage and amps change with the RPMs, temperature etc, so I was looking for someone to let me know what RPMs should I be using to perform an alternator output/charging test, I mean something like this:

"With the engine idling and no load on the charging system (lights and all accessories off, battery fully charged), the amperage output should be relatively low (typically less than 10 amps). With the headlights and heater blower fan on and the engine running at 2,000 rpm, the output should jump to a higher reading, typically 25-30 amps or more. Charging voltage varies according to underhood temperatures. Room temperature charging voltage is generally about 14.2 volts. As underhood temperatures increase, charging voltage drops down to about 13.8 volts. In very cold climates, charging voltage may temporarily increase to 14.8 or perhaps 15.0 volts."

I will read the Bentley, Haynes, and Chilton I have here just to get a better idea of what the standard procedure looks like to test an alternator output.

I will pass discussing the nonsense in my words in a forum... I will also suggest you check the facts before you answer my inquiries since Google makes it so simple, here I will leave a picture of a voltage regulator from a Bosch alternator with the brushes of the alternator attached to it. As I said in my previous post they do come in the same plastic ensemble together, and they are actually electrically connected.

voltage regulator..jpg (28.65 KiB) Viewed 4648 times

Thanks for your help.

[RickHaleParker]

Sense you already know everything, I'll spend my time helping people that need help. Good luck and goodbye.

[sergitin32]

Grow up and behave to this forum expectations.
I know a thing or two, not because I am asking for help means I am an ignorant.

If you don't know what you are talking about, silence is gold!

Bye.

[sergitin32]

So I decided to go hands on and look for answers.

Here is what I found.

The voltage regulator from an older 55amp Bosch alternator is exactly the same than in an 80 amps later Bosch unit, same part number and identical pieces as you can see in this pic. So they are interchangeable. Part number: 1-197-311-008

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The hardware attaching them to the alternator is different though, the newer unit had Phillips than were almost stripped but somehow a Robertson #1 would also fit in there and with some effort, I manage to bring it out. The older hardware is two flat heads, so better for not stripping the head, but actually, the tip of the screw has a square profile and makes it a PITA to find the holes when reinstalling the Voltage regulator into the alternator. I did not remove the alternator from the car, just the VR from it. The newer hardware is easier to strip the head but the tip has a round profile and it's easier to find the holes with them. So after a while trying with no success with the old screws I tried the new ones and it was much easier.

I also remove some of the other wire connections and clean them of all the oil that has been dripping into this unit from somewhere in the cylinder head.

After revealing my brushes in the faulty alternator they came out to be really short, way under the wear limit (7mm) and all dirty with some copperish greasy paste. The 55 amps alternator brushes were maybe 2 or 3 mm longer than these. So I thought I would give it a try.

After installing this older Voltage Regulator and messing around with some stripped bolts in the battery connections, I finally got my other Volvo battery and installed it. Checked voltage in this battery and it was around 12.23 Volts.
Started the car and the voltage at battery connections was 13.96 Volts while idling at 800 RPMs. Idle was steady and the battery sign light was totally off.

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Very satisfied with this, I will now order some new brushes for this Voltage regulator to keep it as a spare. Then when the warning battery charging light start getting dim again I will know its time to change this again, now with the experience of what to do and how to do it.

You can see how to change brushed in this youtube video:



Thanks,

Sergitin32

[lummert]

Good that you got the problem solved.