Got my son a Mazda 3 just about a year ago.
New battery at the time.
Was just fine up until 3 weeks ago, he got in and click click.
Boosted just fine and he was on his way.
Few days ago, gets in and once again click click.
Boosted just fine once more.
Took the car over to the chain garage where I got the battery from (however in a different city) for a battery test.
Battery shows just fine.
I am at a loss and no he did not have any lights on when the car was turned off.
Battery used is a Sears Die Hard Platinum.

 

Welcome to the forum.

You are not really giving much to go on so here is the generic answer.
Well the logic is you have a drain.
So time to get out the digital volt/ohm gauge and start hunting.....
Or take the Mazda back to your chosen 'mechanic" let the shop find and resolve the drain.

 

Thanks for the reply Callisto.
I know it is not much to go on, other than the most it sits is for 2 days yet it seems odd now given that this battery is 11 months old, no prior issues with the battery up until 3 weeks ago.

 

Batteries will go bad before most know or understand why. We replace on average 1 battery about every other day that customers will state exactly what you just posted.
If you read what I posted in your thread again, the date you purchased the battery does not give that actual age of the battery and very few people actual have the battery load tested before they have the battery installed or in your case do first check it. Charging a battery and the battery holding 12+ plus volts is not an indicator of a good battery.
Then and only then you move to searching for negative drain on the battery. Unless it is a drain that can be measured or seen with the voltage dropping quickly meaning in the hundred's scale of the volt/ohm meter in minutes then it is a time-consuming task. I do not recommend then method with a vehicle with so many onboard electronics that need power supply even when the engine is off to start the method of pulling fuses to fond the drain. Unless you know exactly all the connected electronics are you could be miss interpreting the voltage draw as found when in reality it was a normal powered circuit. So, I recommend before you or anyone starts to look for a power drain to get and understand the electronic wire diagram of your specific model and year vehicle.

 

Tried to eliminate a problem by having my son turn off the radio while the car sits.
Thinking perhaps that could be an issue for some power drain but again, it has only become an issue within' the last 3 weeks which I don't understand ...

 

I am not sure how that procedure verified anything?
You really need at least the simplest and basic tool for checking a electrical system which is a Digital volt/ohm meter!