Hi guys. I just replaced battery as it was bad. I previously had parasitic draw which i believe it was car alarm completely discharging (300mA) my battery overnight.
I have grounded alarm and alarm is no longer active (bypassed). I did test for parasitic draw and i see only 0.15 mA so i believe it's all good here from what i can tell for now.

Now when i was testing my alternator whether it's working correctly i see that under idle engine and FULL electrical load heat on high, lights on, radio on and rear defroster on my voltage shows 11.7v and when all electrical off its back to ~12.3

When i increase rpms to 1,000-1,500 rpms voltage jumps starts going up to 12.6-14.00 so that tells me alternator is working and charging during driving but i'm curious if under idle if it's working properly. I know there is voltage regulator and i wonder if under idle what it should show for this particular car?

Is there voltage regulator in 1990 LS400 that would under idle only regulate 11.7-11.9v and would start charging only when rpms are increased or is alternator weak and going bad slowly. Wouldn't want to buy a new one unless needed?

I have Innova 3320 multimeter which may or may not have (+) or (-)~1v variation. This is not Fluke so not sure what the margin of error on this device is. Or could be accurate. Not sure. It uses only auto ranging when setting on 12v testing. Thought i would be specific here about device too. This multimeter has 4.5 starts rating on amazon and supposedly is as accurate as Fluke

Thank you in advance guys for your help

 

It should be putting out that 14 v at idle.

 

I would not doubt the meter. No way it could be causing that.

 

It does when rpms are higher then 1000 so it works but i know that lexus has voltage regulator and i wonder if that voltage regulator is keeping charging low when idle. ?

 

I checked the variation is 0.8% so it could be off almost a volt. I checked my battery this morning and good news is that parasitic draw is definitely gone as battery is at 14.3v after full night.