I had a new battery installed last year and an alternator maybe 6 years ago. If my car sits 4 days I have to jump start it. My mechanic cannot find anything wrong. It seems to me that it’s “leaking” juice somewhere. What should they be doing to find it?
A parasitic draw test will likely find the problem. Your mechanic does not know how to do this so find a better one. Expect to pay for his time no matter if he repairs it or not.
Suspect aftermarket radios, subs, remote starters or alarms as the culprit.
Just like with any other profession, some will be more skilled than others.
Clearly, the OP needs a more-skilled mechanic.
How many miles? Is the problem solved for a while by charging the battery?
Has he actually performed a parasitic draw test or is this one of those eyeball and pray things?
The test is easy as far as finding the problem circuit. Finding the problem in that particular circuit can be a bit more challenging and IMO when it gets to that point a factory wiring schematic is a must have.
The quick and dirty parasitic draw test i always use is to charge the battery with a charger
And then disconnect the hot lead to the alternator… secure the end of the hot lead… because well… its hot…
Wait a day or so and see if she starts up w no problems… if so… the alternator is the culprit.
You could go about this a different way by leaving everything hooked up and monitoring voltage drop … then disconnect it amd monitor more… the first way is easiest and requires less babysitting
Normal current draw on the battery should be less than 50 milliamps when the car is parked and systems are in the ‘sleep mode’.