Mystery intermittent starting problem

my wife’s 2000 Subaru Outback has 37,000 miles. She drives it about 3,000 miles a year mostly on short errands. It’s been maintained regularly and generally runs fine, but twice in the past month, after not being driven for a week, it wouldn’t start: turning the key produced a click only, no cranking. I had to jump it to start it, then it was ok until the next time it was idle for a week. I had the battery(1.5 years old) and alternator (original equipt.) tested, and was told they are fine. The garage found no starting or charging problem. They did a battery draw test and said it drew 17 milliamps. I don’t leave interior lights on, nor was any door ajar. No exterior appliance such as cell phone charger is attached to the car. If it’s driven at least every other day, it starts ok. Any thoughts on what’s causing the problem and how to find it?

Thanks.

How long did the measure those 17 milliamps? Often that “dark energy drain” reduces over a few minutes. You also may want to check out that starter solenoid.

This sounds like a loose connection, to either battery terminal or to the starter. A week is pushing limits of what charge even a new battery can hold to start any car. Add that to a less than perfect connection and you’ll get a clicking sound and little else. If the battery was shot, by the way, nothing would happen when you turn the key after a week of non-use.

Clean and tighten the battery connections. If that doesn’t help, clean and tighten the starter connection. If THAT doesn’t work, start and run the car every day, for at least ten minutes.