my car works great if I drive it everyday. It has recently been raining a lot so I have been driving another car. It seems that if my car sits for more then 2 or 3 days without being started it will not hold a charge, and will not start. I checked my doors and trunk and my key is not in the ignition it is sitting in the cup holder. I cannot figure out why I always seem to need a jump start. My car is a 2005 with 2150 miles on it and a brand new battery. Any suggestions?

 

Maybe you got a defective batt or you got a current draw. Put a voltmeter across the batt post of a fully charge batt and check out how low it goes when you start. If it goes lower than 10 volts the batt is defective and should be replace. You can also unplug the pos. or neg. and put an ampmeter in series with the circuit and see if something is consuming current.

 

What gnj152 said. I'm thinking you got a power draw somewhere. If that's the case then with the ampmeter on (or if you have a nifty inductive clamp) pull out fuses one at a time until the reading drops considerably. After that its a matter of finding the problem wire(s).

 

First, pretty good info. Except, how do you know that this guy knows how to use an AMMETER (not ampmeter). Using the incorrect tool could damage his car, or he could injure himself.

Take your car in and have your battery tested by someone with the proper equipment. Dont just go and hookup a DMM in series to your battery. Most DMM's only can only handle 10A or so, there is going to be anywhere from 100-200A going through the the starter circuit.

To answer the posters question:

Could be

Bad battery
Bad alternator- hence no charge on the battery.
Parasitic drain

 

make sure your trunk lid is closed. then from the back seat open the pass thru and look thru to see if the trunk light has turned off

 

I'm have the same problem with my battery. It won't hold a charge.
I didn't use my 8 while on vacation then it wouldn't start up after sitting for 4 days.
When I called Mazda road side service the lady said that this is a common RX-8 issue.
She said "The battery is pressurized, so if you let it sit for a few days the pressure will drain."

Never heard of a "Pressurized battery" ?

 

LOL! "The pressure will drain."

Just a note for all you Phone Service Reps out there, if it's not in your manual, don't say it.

 

(look i searched!!)

I went to Cleveland over the weekend and took the Rav4 since we wanted to go shopping. I came back 3 days later and my car wouldn't start. I got it towed to the dealership and they found that my car's battery wouldn't hold charge. I was now how before I got a new battery, the starts weren't as quick. I didn't think it was the battery cuz I was still able to turn on lights and stuff...