Is 300ma too much drain while the car is off?
 

Lately I've been having issues starting up the car during the morning, requiring 3 cranks and during the evening with 2 cranks. I am on E85 with modified cranking values. My car is 2.5 years old as well. Also a manual transmission with the measly 390CCA battery lol. Mornings here in CA is now in the 50's F.

Last week, I tested the voltage over night with the battery still connected to the car at 12.7V after an hour's drive, and then in the morning it was at 11.9V which is almost empty.

last night, I took the battery out of the car after an hour's drive and tested it at 12.65V, then tested it again the next day and it was 12.5V. Compared to a new Bosch battery I bought, it tested at 12.7V and stated at 12.65V the next day.

So seeing how the stock battery is still holding its charge somewhat, I plugged it back in and tested the amp draw with the car off. It tested at 330ma which seems high according to some sites that says 50ma should be the limit, but another site said 300-400ma can be common for today's cars with all the electronics.

It's a bit late for me to test pulling fuses to see where the draw maybe coming from, but I was curious if anyone else has encountered something like this.

EDIT: so it's been bugging me, i went ahead and pulled some fuses but unfortunately none of the big ones were the culprit:
horn (recent switch to PIAA horns)
headlights (using Diode Dynamic Always On module but disconnected to test)
radio (added backup camera but disconnected it to test)

Is it a smart key car? Remote starter,alarm?

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I do have the Limited with the smart key and alarm but no remote start. I'll find the fuse for this next and check it out.

300 mA seems like a bit much but I couldn't find any reference in the service manual to what the standby drain should be.

Regarding the battery. Lots of complaints about the stock battery but no one has ever mentioned battery maintenance. This conventional battery requires periodic maintenance. Water is lost due to electrolysis. Have you checked the water in the cells? Instructions are in the owner's manual. If you fill, use only distilled water.

I ran across another post that a member had a draw of 130ma and went to the dealership where they checked a brz on the lot and it drew 150ma so they said that was acceptable.

I checked the fluid level through the battery with a flashlight, the fluid fills to the top but the denser material filled to the low level line which I think is ok?

I ended up installing the new Bosch battery this morning and woke up just now and the car cranked just fine. The real test will be overnight where i'm parking it outside of my work. The last three mornings it would crank three to four times before going.

Started the car up this morning with just two cranks. May need to adjust my cranking values for e85 but the voltage was 12.54v after 12 hours in the cold. It was 13.05v when I left it. Much better than the 11.9v from the old battery.

The high draw is still bugging me though, I'll have to look into it further this weekend.

Stating the obvious but yeah, your old battery was toast. Do you have an aftermarket stereo amp?