ugh, this is such a pain in the ***...its seems like everytime i leave my car sitting out for more than a few hours the battery dies. its a brand new battery. im not even sure if its a dead battery really.... when i try to crank it over the selenoid fires but it doesnt crank over (at least thats what it sounded like). wierd thing is, ALL electronics work...radio, headlights, horn etc..

my dad brought the car to midas one day unbeknownst to me, and thats when he bought a new battery for like $80 ... and the mechanic claimed that the headlights were pulling voltage when the car was off and the headlights were off, so he said there was a short in the headlights somewhere.

so i brought it to the shop at my school so i could work on it and i told the story to my shop teacher. he didn't think it sounded like a short...he thought it was a loose wire on the starter motor. we did a voltage test where we disconnected the negative cable on the battery and touched the neg terminal of the battery and then neg cable and waited for a reading. but we had nothing, its was 0 - 0.1 all the time. my shop teacher said that meant there was NO leak in voltage anywhere...

so he is sticking to the idea thats theres no voltage leak, and its probably the starter motor waire thats lose. im not sure what to think right now, because when im in a situation where the car wont start and i turn on accessory with the key, the battery voltage reads like 10 - 11 volts.

so far ive jumped started this car like 25 times in the past week and im getting pretty pissed off

i drive a 88 trans am, 350ci tpi, new battery

 

im having similar problems with my 87 iroc and tomorow i will finally be doing a voltage test and hopefully i find a short so itll be an easy fixer. my batt and alternator both are new and and my voltage meter reads 13-15 after 8 hrs of being on the charger, then 4 days later its dead. there is definately something drawing power from it and if there isnt then maybe ill take your idea and check out the starter wires.

 

To find your problem, use a process of elimination.

First, even though it's brand new, get a load test on the battery.

Then, start the car and put a volt meter across the terminals. A reading between 13.5v and 15.5v is where you want to be. Any lower and the alternator is not charging the battery, which could be the alternator itself or the belt slipping. Any higher than 15.5v means the alternator is cooking the battery.

Next, connect a jumplead/booster cable from the battery negative post to an earthing point on the engine and attempt to start. If the car turns over strong with this cable, but weak/not at all without it, then the earth strap is the suspect.

If it's none of the above, and there's definitely no drain anywhere, then I'd look at the starter motor.

Good luck,
Si

 

What your shop teaher did was a voltage drop . You want to do a parasitic leak test . This time unhook the B+ cable hook your meter inseries with the b+ and cable . Have all the doors lights off everything off , there should be 25mA of draw it may take 10 mins to drop to this level . If it doesn't start pulling fuses till the it does , remeber don't turn anything on . If that doesn't work unhook the alternator , a diode might have gone out in it . Oh and doing the voltage drop like you did would have told you if you had a bad ground .

 

Well when you jump start the car does it start ok???
If so then there is nothing wrong with your start cct.
More likely a current drain from Acc cct like alarm or radio etc.
Whats the drain on the battery when its just sitting there??
Remember even pulling fuses will send you on a wild goose chase as there will always be a small drain. Its only a problem if its excessive. Also the battery can be faulty even if its new. It can have a shorted cell internally and this will drain the battery very quickly regardless of fuse pulling tactics. best way to check is disconect the battery, charge it on the bench and let sit for a day. if it has internal leakage problem it will be dead in a day just sitting on the bench, speak to your teacher about internal battery resistance and shorted cells.

 

Hey aussie re-read what i wrote , note i stated should be 25ma draw on the battery . If the batt is shorted you can check for voltage on the batt. case . Oh and pulling fuses is one of the best techniques for a parasitic draw . Its called narrow down the items , or circuits .