Charging Voltage ?

[ChillOut]

What should the alternator charge voltage be on the Passat?

At 10 degrees C if you want to be pendantic, and I'd like you to be!

I have done a lot of reading up and it seems that if I want to have a maintenance free battery (using at least one electrode with calcium in it), then the charge volltage should be around 14.4V to 14.8V. Higher than in the "old days".

Our Vauxhall charges at 14.4V.

The Passat is at 14.1V. Is this adjustable, or just a case of getting a new regulator if its too low?

Why do I ask all this? Because I am on my 2nd battery - they have both gone flat with ease. The current one - 3 years old, is showing 12.2 Volts this morning which suggests under 50% charge, yet it runs journeys of 100 miles a day twoce a week (and did this yersterday). It should be 12.75 if fully charged.

Should I use only Lead/Calcium rather than Calcium/Calcium or Calcium/Siver?

[manclad]

Recently had a similar problem see HERE (http://www.vwaudiforum.co.uk/forum/showthread.php?t=109038[/url) although mine had been stood for 10 days

14.1V is on the low side, but it is satisfying all the vehicles load and charging the battery. So after a 100 mile run the battery should be fully charged.

If the voltage is only 12.2V after an overnight stand it sounds like there is a discharge load on the battery.

Would suggest you have a look at the load on the battery with everything switched off.

[snapdragon]

Should I use only Lead/Calcium rather than Calcium/Calcium or Calcium/Siver?

The Calcium Silvers can be charged at a much higher rate of amps without damage, but it is optional whether you do this, they will happily work in a conventional system such as found in our cars.
It sounds as though your car is charging, but is deep cycling by discharging. It is probably at a very low capacity when you come to start, but still turns the engine over very well, this is how modern batteries are, the voltage decay is much slower with discharge and then the voltage relatively quickly drops when the battery is flat.

[vwcabriolet1971]

I assume the 14.1V on the Passat is with a full load , i.e. heated rear window, air con, headlights + fogs, hazards, blower at max speed, etc. ?
It should charge above 14V with full load with engine at about 2,000 rpm.
You could get battery load tested for free at Halfords.