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My battery problems are less than the last couple of years, but still exist.

So here's the whole story:

In the winter (very mild, I guess, comparing with North countries) If I leave the car in the (closed!) parking, for a week or more without taking it for a ride, it will start with some difficulty (as if the battery hasn't got enough power to give), or it will not start, and cable start will be required.

I have to admit that the car in general is used about once a week, sometimes more often, but for short rides, in the city, from home to office etc. so this may be a cause for the battery not having enough time to fully charge.
But, could it also be a problem of the alternator (never replaced) ?
Could the alternator be working in rather less than its 100% ?

After being used, even for a brief trip, the battery should still be able to have enough juice for the car for weeks or even months.

If the battery itself is fresh and still ok, the following possible causes come to mind:

1. Grounding: especially the connection of the main ground strap to the chassis (located roughly underneath the battery tray) is known to cause issues due to contact corrosion or rust

2. Alternator: when bearings are ok, no excessive noise, the alternator itself will usually be fine. But there is a nice little piece fitted to the back of the alternator (2 small screws) that holds the voltage regulator and the pick up brushes. It can never do any harm to make sure this part is fresh, I even keep a spare in the trunk at all times, and they're not very expensive. See sample image for the voltage regulator below.

3. Power consumption: there could be something 'eating' the battery when the car is not in use. For example a glovebox or trunk light that stays on due to a defective switch, or for example a power amp for your car stereo that stays on.

The alternator itself also needs to be grounded properly (it is insulated from the rest of the engine by the rubber bushings). Mine was intermittently charging and put out about 12.2v - enough to keep the car going for long periods, but draining the battery very very slowly. I put a new earth cable on and it was putting out 13v+, no problems since.

Yesterday I had all the earths checked once again, as well as the alternator. The Electrician found everything OK, plus the Alternator produces 14 volts, according to his words.
So the only thing remaining is my nasty habit of taking the car for very small everyday drives, (distances up to 3-4 km), which probably does not provide enough charging time for the battery.

Should do a small trip (80+ km) once per month or so...

Have you checked the power consumption with an ammeter? I was getting a flat battery, so unclamped a battery terminal and put the ammeter in line. Since the only things drawing power should be the clock, and perhaps your stereo, the current draw should be a small fraction of an amp.

Mine was drawing 0.5 amps and it turned out the stereo had been wired in to be powered even with the ign off. When I re wired it, the current draw was undetectable.

If you do find a current draw, start pulling fuses till you find the circuit responcible. Even if it's not a component or switch at fault, it will at least narrow down the options for wiring that could be at fault.

polov8 wrote:Have you checked the power consumption with an ammeter? I was getting a flat battery, so unclamped a battery terminal and put the ammeter in line. Since the only things drawing power should be the clock, and perhaps your stereo, the current draw should be a small fraction of an amp.

Mine was drawing 0.5 amps and it turned out the stereo had been wired in to be powered even with the ign off. When I re wired it, the current draw was undetectable.

If you do find a current draw, start pulling fuses till you find the circuit responcible. Even if it's not a component or switch at fault, it will at least narrow down the options for wiring that could be at fault.

Have done this, yes.
The clock and stereo consumption is normal.
However, I have noticed there is some small consumption from the infrared(?)motion detectors of the alarm system, which are always working, even with the alarm off, even when the car is moving (and the alarm is off for sure)

I think I'd try disconnecting the alarm then. Charge up the battery, and leave the car for a few days, and see what gives.

The drawback is that if it is the problem, your car will be un-alarmed, and it'll start when they hot wire it!

Not bad as idea..!
will give it a try when/if this happens again

I have been trying to sort a few issues with my car too and have been experiencing something similar. Going on the above advice i think my alt is ok as no noises, i will be checking the ground strap though as it does have oil all over it from a leak from the distributor...this may be the issue as just recently my rev counter has been intermittently working so i think i may have found the issue

whats the normal amount of voltage one should get at the terminals? mine read 13.5- 13.7 is that enough?

Yup, that should be ok, believe it should deliver abt 13.8V, that's close enough

Meaning this is what should be produced by an alternator in good condiiton?

Then my battery's only issue seems to be the rare and short drives,(for which I am the only one to blame) as the electrician checked and found the grounding all good and the alternator "producing about 14 volts" (probably meaning something less, such as 13.7-13.