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Discussion Starter #1
Hi guys,

Sorry, I open a lot of post few days but I know here you are all expert for Alfa :)

For people has read me recently, my alternator has rebuild.
But...I have try to check the voltage to verify if is correct or not directly on battery.

So this is the voltage I have when the car is start and idle :
1680523


And when the car is off :
1680524


What do you think ?

Thanks,
Regards,
 

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What is your idle speed? What is voltage at, let’s say 1500-2000 rpms?
 
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That is not enough voltage at the battery

Alternator output should be 14volts.

modern battery technology requires a bit more voltage than when these cars were new.

Here is some info I posted a while ago in the Spider forum.


Battery Chemistry

Battery chemistry has changed, our cars (old Alfas, Bosch, K1, 14v charging systems) haven't.

Traditional lead acid battery, 6 cells @ 2.1 volts = 12.6 volts

lead, acid, antimony - stronger lead plates, more outgassing, more water usage

lead, acid, calcium - less outgassing, ushered in "maintenance free" era but required higher charging voltage. not good for deep discharging GM's Delco Freedom II required 14.8 volts to reach full state of charge

hybrid = lead, acid, antimony on positive grid, calcium on negative grid - cut water usage but still needed regular checking. a little better for deep cycling. Most cars originally equiped with a hybrid had the charging voltage set to 14.3

Gel Cell - typical manufacturer recommended charging voltage of 13.8 - 14.1

Older vehicles with typical charging voltages around 14 volts will not fully charge lead/calcium or hybrid batteries.


There are lots of people that found themselves stuck one morning when their new battery, failed to charge fully, and didn't have enough oomph to start the car. Park a car at the airport for a couple weeks with just the clock, radio memory, maybe an alarm system, that is enough to discharge a non-fully charged lead/calcium or hybrid battery to a point where it won't start the car. (personally experienced this. 3 years, 1 expensive AGM battery, 2 alternators, solar charger to keep it topped off and lots of frustration.)


Foreign car makers did not modernize their specifications to meet newer battery specifications and pushing old technology lead/acid batteries. Bosch was still teaching service techs that 13.8 volts is enough and "a fully charged battery cannot be charged with 14 VDC or higher. Doing so will cause the battery to be overheated and damaged".

in Automotive Electric/Electronic Systems, Second Edition, Robert Bosch 1995, Bosch recognizes the effect of calcium on battery chemistry. In this handbook they recommend that when external chargers are used, lead/calcium and hybrid batteries be charged at no more than 14.4 volts and the charger have a certain characteristic known as "Type IU" which is defined in the handbook. Under the more controlled environment of an automotive charging system, the regulator is temperature-compensated, and can provide voltages greater than fifteen which are sometimes useful. At a modest air-intake temperature of 25º C (77º F), a chart suggests settings between 14.3 and 14.7 volts. (see attached pdf)


If you can get your system to charge (adjustable regulator) within the range suggested by Bosch's newer graph. 14.3 to 14.7 volts at a moderate temperature. The improvement in the life and performance of lead/calcium and hybrid batteries will be greatly improved and less stressful for you.


Self Discharge:
Batteries will lose charge even with a no-load condition. Modern batteries containing little or no antimony will lose 0.1 to 0.2% of their charge per day at room temperature - when new. As a battery ages charge loss can go up to 1% per day and more due to antimony migration to the negative plate. Self-discharge doubles with every 10 degrees C temperature increase.

Storage:
Batteries which have been taken out of service should be stored in a cool dry place. Battery condition should be checked every 3-4 months. If electrolyte density is < 1.20 g/ml or the open circuit voltage is less than 12.2v the battery should be charged. Charging low maintenance and no maintenance batteries with the IU method is best. 14.4v max charging voltage which can be left connected for 24 hours to ensure full charge while still avoiding an overcharge condition.

Charging:
In a vehicle charging system the voltage is limited, this corresponds to the IU charging method. The charging current automatically drops when one or both electrodes are fully charged and overcharging, which can damage the battery, is prevented.

The most common charging type is the resistive or W type of charger most commonly found in unregulated chargers. The charging current drops continuously as battery voltage increases, typical charging times of 12 - 14 hours. Not recommended for low or no maintenance batteries as the voltage is not limited.

Shop and home chargers may generate a constant charging current or have a resistive charging characteristic. Both of these will continue to charge after the battery is fully charged. Maybe by not reducing the charging current enough or even with a constant charging current which can lead to water loss/consumption and postive grid corrosion.

Get a charger with a maintenance free option/selection, that is the difference and why it is there.
 

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So is it fair to conclude that on a Series 2 Spider, in order to fully charge the battery I should have either a traditional lead acid, or a gel cell battery?
 

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You won’t find an old fashioned traditional lead acid battery. I don’t know about gel cell technology availability.
In my spider I had to repair/replace a few connections. The cable from the alternator to the fender wall junction was dropping 1 volt in its short length.

the easiest fixes would be a higher voltage output voltage regulator or an adjustable regulator that you can set for your desired voltage at the battery.

search among old European car sites and you will see the same tales. Also options for a regulator.
 

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Hmm, we've used nothing but plain old fashioned lead/acid batteries in our Alfas without problem, lasting on the average 8-10 years.

The Chevy SS, though, uses one of the flakey AGM, which doesn't hold a charge for all that long, according to what I've read. The battery in ours is really pretty new, and I have to have a sustainer charger hooked up all the time when parked for any length of time. Or, it could be just the newer cars with all the electronics and computers, always drawing some power.
 

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Discussion Starter #10
Ok guys. some news. new voltage measure.
At start stay at 12V around 12.3-12.6V

After small ride with good acceleration. I take again the measure and i have 13.6V (see pictures)

So i think the alternator work great but why not when at start car.
1681037
 

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So you state in post #10 that you now have 13.64 volts. At what engine speed?
In your first post, you show a voltage (at idle) of 12.67 volts.
Perhaps, in your first post, you simply started a cold engine and tested the alternator output at that (early) idle speed. For some reason, cars of this era with Bosch alternators will not "switch-on" the alternator until the engine speed is increased to about 1500-2000 RPMs after start-up.
So, in conclusion, always rev the engine above 2k before testing alternator output.
There are more tests that can be performed to test the integrity of your charging SYSTEM.
So to answer the question that you asked in post #1, I would say, that if you have no other concerns (obvious problems), your charging system is good.
 
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Discussion Starter #12
So you state in post #10 that you now have 13.64 volts. At what engine speed?
In your first post, you show a voltage (at idle) of 12.67 volts.
Perhaps, in your first post, you simply started a cold engine and tested the alternator output at that (early) idle speed. For some reason, cars of this era with Bosch alternators will not "switch-on" the alternator until the engine speed is increased to about 1500-2000 RPMs after start-up.
So, in conclusion, always rev the engine above 2k before testing alternator output.
There are more tests that can be performed to test the integrity of your charging SYSTEM.
So to answer the question that you asked in post #1, I would say, that if you have no other concerns (obvious problems), your charging system is good.
Yes you are right !!!!
When I increase at 1500-2000 RPM - the value is good.
Thanks a lot :)
 

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Bosch alternators requite a stator current to 'start' generating. This current is normally supplied by a 2.0W incandescent bulb AKA the charge lamp. In the Milano/75 the current is supplied by the ARC unit with a resistor. What you will likely find is that the alternator will not start until say 1300-1500rpm, or an abrupt rev. When this happens you could trace back the stator wire (green) through the engine bay and clean its connections all the way back to the ARC unit, and then verify that the ARC system as a whole has good ground and power supplies. there should be at least 7V at the stator wire with the ingition in the MAR position
 
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