Hi guys I just bought a 99 IS200 and the battery died last week evne after a weekend of running it. So I had the batt replaced, the dash lights and headlights used to dim at idle with the old batt, but even with the new batt they do that still so I had the alternator (measuring 12ish V when car running) replaced too. Now wiht a new alternator (not brand new, but refurb off a younger car) the reading (on 1 of those voltmeter plugged into the cigar lighter socket, and also indicated on the lexus' own voltage indidcator dial on the dashboard) is 14 when car is running at normal driving speed (30-50mph) with all lights, fogs, stereo and air con on, the reading drops to 13.1-13.3 at engine idle and all elec off, it drops to 12.7-8 when headlights are on, fogs will make it hit 12.6, and if heated seats are also on, I get 12.5V. When engine is off and only ignition is on, with all lights, air con, etc switched off, the reading is 12.4. Now my question is, is it normal for the alternator to go above 13 only at 2k+ rpm? It seems to me, it falls below 13 when any electrical equipments such as the headlights and air con are swtiched on at idle speed, is that at all normal? A friend had mentionmed that the alternator should produce 14V even at idle speed, and it really should not be affected by the amount of elec equipment you have on as long as the engine is running, you should always get 14? So does it mean my battery or the new alternator is not doing its job? How do I know if it's the battery or the alternator? Or am I just being a paranoia? I do still notice a little increase in light intensity when I rev the car when car is not moving, but not as much as before now, if you don't pay attnetion you probably wont' notice the slight increase in brightness of the headlihgts and dash lights.