Several modules are always powered. What is the typical current drain on the battery when the key is OFF?

There could be several reasons why the battery in your 1996 Jeep Cherokee is still draining and losing charge after replacing the alternator and computer. Here are a few things you can try:

1. Check for electrical issues: Make sure all the electrical components in the vehicle are functioning properly. This includes the headlights, taillights, interior lights, and any aftermarket electronics. A malfunctioning component could be causing the battery to drain.
2. Check the battery connections: Make sure the battery connections are clean and secure. Loose or corroded connections can cause the battery to drain.
3. Check the battery cables: Inspect the battery cables for any visible damage, such as fraying or corrosion. If the cables are damaged, they may need to be replaced.
4. Check the charging system: Make sure the charging system is working properly. You can use a voltmeter to check the battery voltage while the engine is running. If the voltage is not within the normal range, there may be a problem with the charging system.
5. Check for parasitic drain: A parasitic drain is a small electrical current that continues to flow even when the vehicle is turned off. This can cause the battery to drain over time. To check for a parasitic drain, you can use a multimeter to measure the current draw on the battery. If the current draw is higher than normal, you may have a parasitic drain.

If you have tried these steps and the battery is still draining and losing charge, it is possible that the battery itself is faulty or not functioning properly. In this case, you may need to replace the battery.

Sounds like a bad diode in the alternator, feedback to ground draining battery......check alternator.....always disconnect battery ground cable to avoid arcing and shorting the diodes in the alternator....connect negative battery cable last when working with polarity sensitive devices..........

Did you let the vehicle sit for 30 min. before testing ? Modules need to time out (go to sleep - power down etc.. How are you testing ? Have a ammeter inline with battery negative cable and negative battery post . Have any doors open ( door switch closed ) Key out of ignition ? How much current ? 50 milliamps max !

A failed/ worn out battery or a current
drain you have to find

Could be the alternator
Could be many things

No-- it appears that something is NOT turning off or
going to sleep

Google or You Tube Video how to do a Parasitic
Current Drain Test

Remember once you close all doors, they stay closed
or your starting over

It may take a half hour before modules time out

Best you have a wiring diagram & an amp clamp or
volt meter, to put into one of the battery cables, to watch
for the drain (MilliAmps) as you remove the fuses to isolate the circuit with the problem

The alternator diodes were checked out with a scope
or checked for leakage?

Process of elimination-with a digital voltage meter hooked up to the battery, remove fuses one-by-one. If the voltage continues to drop after removing a fuse, reinstall it and go to the next. When you find the drain, the voltage will actually go up-you have found the source in that circuit. This is time somewhat consuming and is easier to do if you have a helper to observe the meter, but you will find the drain this way. Also, (a little more involved) you can use a test light and hook it in series to the fuse and the fusebox, if the light go on, that circuit is draining-some circuits are supposed to draw current (like the radio memory or the interior lights if the door is open) but if, say a radio amp draws current (common GM drain) you found it.

Hi
A car battery can run down for any of several reasons:

• You accidentally left the lights on or some other accessory that pulls power from the battery even when the ignition key is off.
• The battery is not being recharged while the vehicle is being driven (you have a charging problem)
• There is a key off parasitic electrical drain on the battery because a relay is sticking, a module is not shutting down, or there is a shorted diode in the alternator.
• Your battery is old and will not hold a charge anymore. The battery needs to be replaced.

Most of the time if the battery is fairly new and keeps getting drained have the mechanic check the alternator if its charing the battery.
Thanks for using Fixya.

No such thing. If you have a new battery, and the alternator's testing fine then there's obviously something draining the battery.
You'll need a multimeter for this. First off, once started, test the battery voltage at idle. Then increase RPM to about 2000. The idle reading could be as low as 10 Volt(since you just put a massive drain on the battery but should pick up with RPM to aboout 13 Volt at least. It could even go up to 14 Volt.
If that is fine, shut down. Disconnect the neg pole on the battery. Switch your multimetre to Amps(You may have to move one of the meter wires to a current measuring connection on the meter.) Connect the leads between the neg of the battery and the cable that came off it. A reading any larger than 0.5 amps (500mA) could mean trouble. First thing I always check for is trunk and glove compartment lights. They may not be turning off with the lid closed. Next is aftermarket amplifiers. If incorrectly installed it does not shut down and drains the battery in no time at all.

You need to do a draw test. Do you have an ammeter?

I would first have the alternator checked by an auto electrician to ensure it is working correctly and is providing the correct volume of current. It may be faulty and when driving you will be drawing battery power instead of power from the alternator to run the electrics. This will drain the battery.

Alternators do not last forever and if you are still running the original unit it is likely to be on it's last legs and you will need a replacement unit.