My battery was being over charged and then sometime later not being charged at all. I replaced the alternator with a rebuilt one and verified after installation that with the lights and heater fan on I got between 13.0 and 15.3 volts at the battery per the information that came with the alternator. Now the battery seems to be overcharging because I always have to add water to it - like after nearly every time I use the car. With lights and heater fan on I get about 14.6 volts at the battery. I thought the regulator was supposed to keep the voltage near 13.8 volts no matter what the load - that's the purpose of a regulator. Is there some way to adjust the regulator to get the voltage where it's supposed to be? The rebuilt alternator came with tested specs that included a voltage regulator set point at 14.59 volts. The original installation check of between 13.0 and 15.3 volts seems to me be a very wide regulated voltage range.
My 240 Volvo wagon has 333K miles and the alternator was the first part I have had to replace other than normal maintenance.

 

From the Bentley manual:
"The regulated voltage (engine running) should be between 13.8 and 14.8, depending on temperature and operating conditions. If the voltage is higher than 14.8 volts, the voltage regulator is most likely faulty."

I measure ~14.5 volts on mine during idle.

 

Is that ~14.5 with no load or with a load? If with a load what did you have turned on. If you're reading ~14.5 and mine is ~14.6 I'm normal, but then why is my battery is being overcharged (battery fluid all over the top of the battery and battery fluid barely above most cells after just 50 miles driving).

 

14.5 no load, sounds like a problem with the battery, or maybe a short somewhere???

 

Just as a bad battery will fry your alternator eventually so too will a bad alternator toast a previously good battery. Your battery needs to be load tested. If you're really concerned, there are adjustable voltage regulators available for the Bosch alternator. www.davebarton.com has 'em. They work great!

 

Thanks for the information. It may be the battery since it took quite a beating during the time the old alternator was going bad. I'll take it and have it tested. It does start the car OK.