battery wont keep charge when cars off

[goj_cloud]

ive just changed the alt to a dohc alt because the sr alt went out, the alt works great but im havving a problem. when the car is off the battery will loose its charge. i took the battery to auto zone and it tested good, and i know that the alt is good since the battery and brake lights dont buzz anymore. what else could make the battery loose its charge when the car is off?

[killablue240]

you could have a short circuit, or something thats staying on in the car that slowly drains the battery, but im leaning towards the short.

[goj_cloud]

how would i find the short circut, im no good when it comes to wiring

[draggin93]

You need a multimeter capable of reading current (amperage). Anything over .5 milliamps will drain your battery overnight. You will have to test each circuit individually to find out the cause of the problem.

If you have an alarm or an after market stereo I would start there.

[goj_cloud]

it happend after i changed my alt i dont know if that helps

[draggin93]

Try disconnecting the alternator overnight then. It's not very likely, but you could have an issue with your rectifier.

[goj_cloud]

Try disconnecting the alternator overnight then. It's not very likely, but you could have an issue with your rectifier.

you mean disconnecting the connector or the ground? what is a rectifier and what does it do?

[draggin93]

Disconnect the positive from the alternator. If you only disconnect the negative it will still probably get a case ground.

The rectifier is built into the alternator. It basically changes the AC signal from the alternator into a DC voltage that your vehicle can use.

[draggin93]

I'm also not using the SR alternator. I had fitment issues with mine and I decided to use my stock truck alternator with the SR pulley.

What do you mean by battery and brake lights buzzing?

[goj_cloud]

tahts what happens when you have a bad alt but i changed it and its fine now

[goj_cloud]

but im jus ognna take off the - cable everynight till i figure out whats goin on, also can a damaged - cable cause this problem?

[juls213]

Hey buddy this is what u do, get a multimeter and check if u have 12v when car is shutt off then see if you have 14v when car is turned on. If u have 14v when car is on this means the alternator is working. Next u want to check for a draw on the battery, 1st disconnect the negative terminal and hook up a test light to it so one side of the test light goes to the disconnected negative terminal wire and the other side of the test light goes to the negative terminal battery. You will see if you turn on your lights the light will turn on that means the circuit is closed and operating. You can see what thing is on all the time and ultimately draining your battery by disconnecting fuses one by one. Good luckINFINITI TECH

[goj_cloud]

thx i will try that