I replaced the faulty alternator on my recently purchased 240 1990 with one rescued from a low mileage 1986 240 I get readings of between 10.6 and 11 volts at the battery posts but the readings if I connect my meter to the smallerpost on the alternator and the ground to the wiper motor are varying between the high 14s and almost 16 volts.

When the engine is running the red light on the instrument cluster lights up but it dims when I run the engine faster. Could there be somethig wrong with the battery? It is almost two years old with a 6 year prorated warranty but I have had to recharge it two or three times in the past week because of the faulty alternator. What else should I check? When the engine is not running and the battery has been on the charger the reading at the battery posts is slightly over 12 volts.