I recently replaced the battery and alternator on my 98 Diamante. No problems until a a few weeks later. After driving it for 30 minutes or so, the low battery light and the brake light on the dash come on. Sometimes they go off again and sometimes they don't. I have had the battery and the alternator checked and both showed no problems. The car has never failed to start and the battery seems to be charging as it should. I've put my battery charger on it and the needle is almost on "0" and in a couple of minutes, it shows to be fully charged. Any ideas?