All,

So I get a call from my oldest this morning on his way to work.

Seems the car has just plain died and he's sitting on the side of the road. As we're talking over the phone, he notices that the D + connection off of the alternator is not attached. He attaches it, but no joy, the car still won't start.

I show up, and check the voltage at the battery. I've got 11.5 Vdc. We jump the car and it starts. I check the battery again, I've got 13 Vdc. Not good at all, but its charging.

I follow him home and as of now the battery is being charged while it sits there. I'll have to check when I get home as to when I bought the battery last, but I have a couple questions first.

1. Other than the D + connection telling me whether or not the battery is charging, does it do anything else,

2. How concerned should I be about 13 Vdc at the battery? I know I need to check at the alternator, and am kicking myself now for not checking it, but we were both in a hurry. I'll check tonight and report back.

Thoughts???

Thanks,

Matt

Hi,

The answer to the first question is yes!

I provide the initial kick of current to start the magnetism inside the alternator.
That wire also turns out the battery light on the dash once it see the current starts coming out to charge. Check to see if the light burns when the engine is off but the key is ready to start.
He may have a burnt out bulb as well. With the wire disconnected he may be used to not seeing it do anything.

Next questions answer is self explanatory.
The battery was so low in charge the system or the alternator's voltage will read slightly low in tenths of a volt.

Keep an eye on it to see if it recovers between 13.2 and 14.2. Look for a mean or average number.

Check the resting voltage of the battery, after its fully charged, over a day or two of sitting.
This can give an indication of the battery's age. Again, watch the tenths as it dramatically shows the overall capacity and capability.

Next thing is to install a voltage meter in the dash so all can be monitored.


Phil

Phil,

Thanks!

I checked the batteries voltage while on the charger when I got home from work today. It read 12.8Vdc.

I started the car and I read the following:

- at the battery 13.8 Vdc,
- at the alternator 14.2 Vdc.

I also checked the age of the battery. Bought it back in July of 2012, so its near its end of life.

I'll check everything else again tomorrow to see if everything is headed in the right direction and then report back.

Matt
--
1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245

So here's the update we've all been waiting for, especially my son.

Please reference the following post as Arts diagram for temperature vs. charging voltage means a lot here, and makes sense when you stop to think about it.

https://www.brickboard.com/RWD/volvo/1656983/220/240/260/280/rebuilt_alternator_question.html

So here I go.

Drove the car to and from work today after battery was charging all night.

Results are:
Leave house:
Battery voltage with car running (cold): 14.2 Vdc
Alternator voltage with car running (cold): 14.3 Vdc

Arrive at work:
Battery voltage with car running (hot): 13.7 Vdc,
Alternator voltage with running (hot): 13.8 Vdc.

So at a glance these seems bad, but once you take Arts chart into account, the actual numbers seem very reasonable.

On the ride home I got very similar, if not identical numbers.

So that we all understand here, this alternator is new to this car, and was pulled from a PNP. It was brand new when I pulled it as it was the only shiny thing in the engine bay, not to mention the brushes had hardly worn a grove into the copper sleeve that they run against.

So as an experiment, once home I drove my 91 to the gym and home as I wanted to see if I would get similar results, particular with the drop in voltage as the temperature went up. So in my 1991, I have just replaced the alternator with a freshly rebuilt one that I finished about a year ago.

My numbers are:
Leave Home:
Battery voltage car running (cold): 13.8 Vdc
Alternator voltage car running (cold): 14.3 Vdc

Arrive at the gym:
Battery voltage car running (hot): 13.3 Vdc,
Alternator voltage car running (hot) 13.8 Vdc.

So for the moment, please overlook that I have an issue on this car, which needs to be addressed, and will be.

What I want you to look at are the numbers. In both cases the 89 and 91 alternators decrease their output voltages as they get warmer, which is exactly what the chart from the previous post points out will happen.

I know the battery in the 89' is old, and will be replaced soon, but as far as I'm concerned, this case is closed and my son can once again drive his car without and fear of breaking down on the side of the road. In case you were wondering, the D + line most likely got knocked off on Friday when we changed the oil and filter.

Note to self, check everything, and then check it again.

Thanks to everyone for listening and giving all the advice, which I take in like a sponge.

Matt

"Short of disassembling the unit, that's about all you can do. I cannot give a recommendation on a supplier, as I've always gone to the junkyard for them. If you do that, one mistake I can help you avoid. That's the one I refer to as my magpie mistake. You see one sitting high and shiny in a 740 -- easy to pull, and almost looking new. It turned out to be the reason the car was in the PNP, most likely. The spray-and-pray rebuild was one of the worst I've ever seen. Go for the greasy one, maybe."

Full text in here: https://www.brickboard.com/RWD/volvo/1646093/220/240/260/280/dim_battery_dash_lights.html

Yes, temperature is important to the millivolts column. And especially so in July on a 240, inches under the exhaust manifold. Someone asked how the D+ connector came loose on your son's alternator, and it reminded me of the time I'd forgotten to fasten one.
--
Art Benstein near Baltimore

A man's knowledge can never outweigh his experience.

Hi Matt,

Thanks for the post back. It sounds promising that the alternator's insides are working like that are suppose too.

Porkface's post brings up a valid point about the differences in voltage drop readings from the two points you tested on.
I will suggest for you do a parallel voltage test with your voltmeter to see if there is any discrepancies on either of your two cables running in between the alternator, the starters joint connection and those heading up to the battery.
Also you will want do the same test on the negative cable.

I say this as, You might have corrosion under the insulation at the terminals. It can be on the terminals of the battery or a not so tight nut at the three points on the positive cable.
There are two on each of the negative cables. One one the engine and one on the cars body. Check them all!

A parallel meter test shows the a voltage reading of "zero" if the meter is not across the circuits voltage potential.
Any reading above 0.02 volts means there is some resistance causing the reading not to be "zero." These numbers 0.00 on a digital meter or analog meter will be on its lowest sensitive range.
The .02 is the upper limit of a great conductor and cleanly connected circuit.

If you see a higher reading, above the limit, this means the meter is seeing a resistance someplace in its parallel buddy! It think it is essential across the posts or the potential voltage being applied. Or it got something separating it from being only on one side of the circuit to get a Zero.

You put your leads from one end of the wires to the other end on the same side of positive. And likewise on the negative side, end to end.
I don't if it totally required or not but, I turn on something in the car like parking lights or headlights to have some current being drawn so the cables are actually working a little.
With the engine off you Lay your leads out from end to end and see if you get that number to be "Zero." If so, things are good!
If not you need to clean or tighten the ends or inspect the battery cables. The ground, as short as it is, is very important. It's more than people give it credit for.

The battery as Pageda says might flunk a load test or you meter is a little out of calibration. If the battery had been sitting of the charger long enough to obtain the loss of residual charge voltage the highest reading should be 12.65.

If the battery sits, say, a couple days and drops to 12.45 or lower the battery is old and going south. At .45 the battery has lost half of its charge.

Another telltale, is if it does not take long for the charger voltage to come up to shut the charging rate down, it means you don't have a big battery anymore.
Some of it has "straight lined" or shorted internally, usually by the aging of the plates sulphating.

Wonder what caused the D+ wire to off.
Looking forward to hearing of the outcome.

Phil

"I also checked the age of the battery. Bought it back in July of 2012, so its near its end of life."

Yes get it load tested, I would bet it fails!

Dan

check your connections. .4 voltage drop is too much. should be .2 or less. good luck, chuck.