Put an alt. in the FC, now battery keeps dying.

[Devioustsi]

@boardjnky4

i had a bat alternator in my civic that would charge the battery when the car was running, and drain it when the car car wasn’t running.

disconnect the wires from the alternator and see if the problem dissappears

Yes try this because if the voltage regulator is trying to regulate voltage with the car off it will drain the battery, in this case you would have the exact problem you are having. Perfect charging and voltage and power drain when off if all you changed is the alt, check there first. Besides the obvious possibility of the battery being fubar from the overcharging.

[91MR2]

Wel guys, the more I think about it, the more this scenario that Gary and Boardjnky suggested makes sense…

This morning I pulled my MR2 battery and put it in the FC, and go to leave for work again tonight, and it’s completely dead…AGAIN.

Time for another alternator I guess…

[bracketracer]

Joe…wait just one second. I’m shocked nobody has even mentioned doing a draw test.

Make sure the battery is charged completely, meaning 12.6v. Remove the positive cable from the battery, and either mount a test light or an ammeter between the cable and the battery post. If the test light is bright or you’re drawing more than 50mA, then start pulling fuses until the draw goes away. Once you determine which circuit is causing the draw, look at a wiring diagram, find out what is on the circuit, put the fuse back in place, and start unplugging components until the light goes out or the draw goes away.

[nitroinsane]

i am going with a draw i have never done what bracketracer just described but i really wish i knew this trick a long time ago lol

[boardjnky4]

disconnect wires the alternator and use a multimeter to get a voltage reading from the battery, then check it an hour later and make sure its the same. Then do the same thing with the wires connected to the alternator. If it starts draining this time, then you’ve found our culprit

[nitroinsane]

@boardjnky4

disconnect wires the alternator and use a multimeter to get a voltage reading from the battery, then check it an hour later and make sure its the same. Then do the same thing with the wires connected to the alternator. If it starts draining this time, then you’ve found our culprit

i have never seen a alternator while not running cause a drain

[boardjnky4]

@nitroinsane

i have never seen a alternator while not running cause a drain

it happened to me rather recently…I went through those exact steps and found the cause to be the alternator. Put a new one in, problem solved

[Boomin99GT]

I was going to say… current draw test would tell you if theres something wrong. I’ve seen everything from trunk pins to radios cause excessive draw while the car is off and cause similar problems.

[Harvey]

@bracketracer

Joe…wait just one second. I’m shocked nobody has even mentioned doing a draw test.

Make sure the battery is charged completely, meaning 12.6v. Remove the positive cable from the battery, and either mount a test light or an ammeter between the cable and the battery post. If the test light is bright or you’re drawing more than 50mA, then start pulling fuses until the draw goes away. Once you determine which circuit is causing the draw, look at a wiring diagram, find out what is on the circuit, put the fuse back in place, and start unplugging components until the light goes out or the draw goes away.

Yea, this is the right way to go about it. I’d probably use a multi-meter in line with the battery cable instead of a light. If you suspect the alternator you will be able to confirm by unplugging it and watching the value on the meter go below 40 or 50 mA

Good Luck.