MrGlock

Ive had to jump my car every time i start it, and its not the battery thats brand new. I got the battery brand new with the car which i purchased about 2 months ago. The only modifications ive done are decat, and catback. The o2 sensor i had would not fit into the new bung so i capped it off. And never had any electrical issues until i did the exhaust. Bit of a head scratcher here, i dont have the means to check every single wire on the car. I also dont have the money to bring it to a mazda dealer to get charged up the ***. Please if anyone knows the cause of this issue. Last night i drove 45mins home from a car meet and the battery was completely dead literal seconds after shutting the car off my locks would no longer work so i had to reach across the passenger and lock it manually. This problem had dumbfounded me ive replaced the battery terminals and i have no other guesses so here i am. Any information helpls thankyou

dannobre

iTrader: (3)

Electrical is pretty easy.... there is a generator/alternator that charges the battery when the vehicle is running... and everything else drain it.

Do you have access to a multimeter or a friend that has one?
Figure out what the resting battery voltage is with the car off. It should be about 12.6 volts with a charged battery

Start the car... voltage should go up to 13.5-14.3 volts... that means the alternator is working. Lower than that your alternator is likely not working.
In order to get the battery to charge there needs to be a good connection between the alternator and the wiring going to the battery. Often if there is a poor connection the battery doesnt charge

If the battery doesn't charge then you will be OK when the car is running... and when you shut it off it wont start again

If you have full voltage to the battery and the starter doesnt work then you likely have a bad connection between the battery and the starter or a bad engine ground.

Always remember that ground is just as important as the power side with automotive wiring... if the engine ground is bad though there will likely be more issues with the way it runs...

Also... dont assume that a battery is good because it is new.... they do fail

Also...if you have a high drain when the car is off from something staying on... it will drain the battery fairly quickly depending on what it is. Trunk light or something can flatten the battery overnight. If you dont charge the battery completely it also can die overnight. Driving around town wont charge a flat battery very well from the alternator especially if its a short trip

MrGlock

I have access to a multimeter, and i made sure to do the obvious of checking the trunk light, tail lights, interior lights etc. I fully charged the battery before leaving my house, took it on the freeway for 45 mins. When i returned home and shut it off immediately nothing on the dash, no lights no dings, lock button stopped working. When i was driving on the freeway i rolled my windows up which cut power completely in the car and i roll started it at like 65mph with zero power steering. This issue completely ruined driveability which is sad because this is my favorite car with the best driving experience for the money in my opinion. I can replace some of the ground straps associated with the engine although i dont have money to start buying random parts hoping it fixes my issue. Ive over nighted new positive and negative battery terminals to rule that out as the issue. I will go over the car with a miltimeter that i borrowed from a friend and give updates i really appreciate your help, ive been through multiple posts on rx8 club searching for answers before i started reaching out on here to figure the issue out. My closest mazda dealer is 40 miles away and i cant afford to tow it there or afford to pay whatever their hourly rate is

dannobre

iTrader: (3)

Sounds like its not charging properly to me

Check the alternator wire to the fusebox to make sure its got a good connection

If you have an Autozone or the like close they usually can test the alternator for you for free...

The power steering draws a lot of power... so with low battery and alternator it would make sense it would quit. Same with the window motors.

MrGlock

Sounds good i will check everything you said and take it to get the alternator tested. Last night when i got jump started when i turned the wheel it shut off again, and had to give the motor some throttle to have enough power in the system to be able to steer without the car shutting off