Car not starting in cold weather

[jshortty1]

Hi Folks,

2004 Mazda 3 2.3L Velocity Red+Rust

For the past 4 days I've needed a jump on the first start of the day due to cold weather. My battery is a magnapower (OEM) and it's 1 year old. I had the same issue last year which is why I had the battery replaced (by a mechanic like an idiot). I bought a portable jump starter for this reason and just to have. I also have a 300watt amp that powers my subwoofer. I believe my battery is dying overnight in the cold because each morning my radio starts in 'demo' mode as if it was brand new. There are also other signs like my trip monitor resetting. Once I get my first start of the day, I have no issues starting it during the day.

I've read here about putting a 24F battery for extra CCAs but before I buy, I'm wondering if theres a way for me to check if something (like the amp) is draining the battery overnight and combined with the cold is making it unable to start my car or if the battery is just a dud. Also should I go for the AGM version or just the regular is fine. I've already spent $200 on a NOCO jump starter and would like to keep my expenses to a minimum.

[jshortty1]

I should mention that I have confirmed that my amp is turning off so the remote wire is working as it should.

[jeff7670]

Is your amp powered directly from the battery? Try removing the fuse. Sounds like you have a slow drain. My 2007 Mazda 3 has the factory battery in it and runs fine. -30 this morning and it started.

[2012mazda3hatch]

May need a capicitator to hold the current or give it an extra jolt instead of taking it right from the battery