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Default new battery still losing powers
Specs: 92 sc300 ( 169 k on chasis )
1 jz tt motor ( 50 k)


i been having this problem for couple weeks now and still havent been able to figure it out. i had replaced 2 new battery already. the problem is that after everytime i replaced a new battery the car works fine. but the thing is that if i dont drive my car for 3-5 days the battery voltage goes from 12.86 to like 3.86 which i cant even crank the car at all. all the light are very dime. i also changed out new battery terminals connectors as well. the other day i went back to autozone for them to check for my alternator again just to make sure. they said that the alternator amperage is not holding the volts. its at 40 ish when it is suppose to be 50-60. i know that when the alternator are bad its suppose to die randomly when its runnning which mine doesnt. but when its parked its draining battery over night. is it possible that the alternator drain battery when its not on?any info i did appericates it guys.thanks in advance.

 

yes, a bad alternator will leak power back into it's windings when the car is not off...

not sure if the lack of amperage is a real problem... it's definitely less than its rated for but doesn't always condemn it as the source...

I would also look for current draw from lights, motors, accessories, etc...

 

If your voltage when the car is running is above 13-13.5 volts, then you are probably ok. I would be looking for voltage draws like mitsu said.

 

Take the alternator to a reputable electrical shop and get the diodes checked- not an an autozone but an honest to God electrical motor repair shop. F'd diodes will discharge the battery. If they sign off on your alternator start looking for stuff stuck on inside the car..

Finding stuff stuck open is a royal PITA.

You'll need to get a test light, what I typically do is disconnect the (-) battery terminal and put the test light in series between the batt. terminal and the cable.

So, the test light becomes part of the - side of the battery cable.

Drop all fuses in the fuseboxes, insert them back in one at a time, and watch the test light. When the test light lights up, you need to determine if it's supposed to be on now (circut that powers memory to the radio comes to mind)

If it's supposed to be on, make note of it and continue putting in fuses until you have it all written down. Obviously, when you put a fuse in and the light lights up, you have current going through.

You will need a volt-ohm meter to see how much current is being lost, but at most you should be in the milliamps voltage draw if all is working well..

PS I'd also disconnect all aftermarket stuff (head units, whatever) before you proceed to eliminate the possibility of that falsely lighting up the test light...

good luck.

 

thanks for the tips guys. i will definitely take out the alternator and go have it check it out. and then check all the stuff inside the car. etc and lastly about the test light. i will keep this post update when i figure it out. thanks again.

 

I strongly suspect you have issues with the diodes shorting - that will smoke your battery quickly..Check that 1st.

Remember, under normal circumstances if you leave the domelight or stereo on all night it wouldn't do that to this car...

 

btw this might sound stupid but whats a diodes shorting? i am not really good with the whole wires and electric stuff.

 

simply put, a diode only lets power go one direction... bad diode(s) can allow current to flow backwards into an alternator which is bad, mmmkay