I've got a fairly significant power drain on my battery I believe.

Brand new (1 month old) FD alternator in S4
Newer Optima Red Top Battery (6months old)
Battery Relocated to trunk.


I've had both the alternator and battery tested at autozone and they both check out. If I charge up my battery overnight on my charger it'll be good for about 24 hours and it'll be drained down to ~10 volts and I can't start the car. I took 3 longer trips (about 4 hours each) and then threw my battery on the charger again. Took it back to autozone and it still checks out. Basically I've got something draining the battery at a quick pace. If i do the current drain test by disconnecting my + terminal and placing my meter inline it pegs the meter in milliamps. I've got a draw well over 250mA, I put it to a digital meter and it measures 3.6amps...... (seems damn high, not sure if its measuring right). I yanked fuses 1 at a time in the foot panel and the panel under the hood. None of em made a difference in the current draw. What else can I check? Is it possible for an FD alternator to drain a battery when its off, starter, coils, relays? What else can I check. Thanks for the help.

 

3.6 amps is very high, that would be the equivenlent almost of having the dash lights on.

If you disconnect the alt does the draw go away???

Unfortantly disconnecting is the test to isolate where the draw is. You'll need to continue disconnecting anything wired until thr problem goes away, and then trace it down on that circuit.

The starter would be the next thing after the alt to check.

 

I would carefully check the back of the alternator with your hand, after the engine is dead cold. That sort of wattage, if indeed it is going through the alternator (bad diode) will keep the alternator heat sink rather warm. Disconnect the large red wire and measure any current that might flow between the wire and the stud as proof. Good luck.

 

if you pulled all the main fused under the hood, atl and starter are next, after that i would check the main wire going from the battery to the main fuse, theres a connector on that wire

 

Sounds like the alternator is draining the battery. This is a problem I had when I put an S5 alternator on my S4. TO TEST: Pull the plug out of the back of the alternator. See if you still have a current draw. (I bet you won't)

If this is indeed the problem, you'll need to install a relay that is ignition switched. Then splice the relay inline with one of the wires on the back of the alternator. Good luck

 

Disconnected main fuse, draw went away. Disconnecting alternernator no effect on draw. Had battery disconnected over night just to make sure it was holding a charge, which it is. So if the draw goes away when the main fuse is out what does that mean, is the starter fused there?

 

that could mean anything, the main fuse should essentially disconnect the battery, the main is usually where ALL other components draw from, everything.

 

i had the same problem when i moved my batt to the bin and all the bs started. this is how the problem is solved what i did was went to auto zone and bought a 1992 mercury topaz 2.3litre alternator, has the same exzact case and it puts out 95 amp with no problem. then i ran 4 gauge wire to the battery,then a separte wire the the car. the grand total for this mod was $110.00 for alt $ 45.00 for wire. now my voltage is 13.9-14.2 all the time.

 

ya that helps reamia.......


the main fuse is just connected to all the ones in the foot panel

are you sure none of the ones at the feet stop flow with the main on still in?

the starter has no fuse.

 

Turns out it actually was the alternator. I went thru today and pulled all fuses and checked a whole bunch of stuff. My meter was reading incorrectly, I got a different meter and I had 400mA with the key off, yanked out the plug for the voltage regulator it went down to appx 30-50mA draw. So low it didn't even illuminate my test light. I guess the s4-s6 alt switch needs a relay because they're in a different spot on the circuit. I'll be adding a switched relay on monday and report back with results.