I have an '04 TSX with ~70K on the clock. I bought it new and as a college student, I leave the car at my parents house in the garage where it can go weeks without being started or driven. At first, when I would try and start the car during a visit, I realized it was because I was leaving the keys in the ignition and that was drawing on the battery so I stopped doing that and it seemed better. Then, it came to the point where the car wouldn't turn over so I completely replaced the battery with a high quality battery which was 2 summers ago. The battery is essentially brand new and draws a strong charge when tested. Recently, the car has been giving me trouble again and I know for a fact that it isn't the battery. I checked everything and there are no lights on; what else could be drawing on the battery? Could it be the alternator or the starter? Any advice is welcomed. Thanks fellas!

 

Have you tried jump starting the car?

 

How many weeks of not driving are you talking about? 2 or 10? There's a big difference between the two. Things like your nav system, radio, and ECU draw power even when the car isn't running. That's why they reset when you remove the ground from your battery. They can't draw the power they need when there is no ground. If you leave the vehicle alone long enough, the components will draw all of the available power from your battery.
This isn't normally a problem because vehicles are normally started and driven around regularly so they recharge the battery all the time. If you're leaving yours in the garage long enough to drain the battery, you could have lots of problems starting it when you get back to it a month later. Try disconnecting the battery when you leave it parked for longer than a week. See if you have the same problems after reconnecting it.

 

Recently, it's been no more than 2 weeks, I only go to school about 35 minutes away and I usually make it home to take it out for a drive. I'll look into disconnecting the battery. Any other suggestions? Do you think it could be anything else?