I am new and have a problem I am hoping someone will know how to fix. I drove my car and turned it off. Its been running fine with no problems. Went to leave about 45 minutes later and the car barely turned over then stopped, completely shut down with nothing working. The dome light under the hood stayed on for a couple of minutes then went out. The battery drained completely. Tried to jump the car with no success. Replaced the battery and still would not start. I put a meter on the brand new battery and saw the voltage just dropping slowly as long as both terminals were hooked up. Something is draining the battery. I checked every fuse in all three boxes and everything is fine there. Could it be the ingnition module? bad coil?
Need some help from the pros

I am new and have a problem I am hoping someone will know how to fix. I drove my car and turned it off. Its been running fine with no problems. Went to leave about 45 minutes later and the car barely turned over then stopped, completely shut down with nothing working. The dome light under the hood stayed on for a couple of minutes then went out. The battery drained completely. Tried to jump the car with no success. Replaced the battery and still would not start. I put a meter on the brand new battery and saw the voltage just dropping slowly as long as both terminals were hooked up. Something is draining the battery. I checked every fuse in all three boxes and everything is fine there. Could it be the ingnition module? bad coil?
Need some help from the pros

I know nothing about cars, but I will venture a wild guess. I would think that if the problem really were a battery drain, the new battery would have started the car at least once. For what device could possibly drain a new battery so much as to prevent starting?

After ignition, I think the car is supposed to run off juice from the alternator, but the whole circuit has to be complete. What I mean is, I think the juice still circulates through the battery even though the alternator is the source of that juice, because the dynamics of the charging system are.more complicated than is usually assumed. What I am saying is that if the positive side of the circuit has loose connections or corrosion, this could possibly (?) result in both (1) the alternator failing to charge the battery, resulting in battery drain, and (2) a low cranking amps condition, making the car hard to start – a condition possibly made worse if your new battery has less cranking amps than the old one.

Come to think of it, by that same logic (the need for the circuit to be complete), you'd better check the negative side of the circuit as well for loose connections and corrosion.

I think there is always some battery drain, for example the clock is always running, and most radios need juice to remember which stations you like. It is usually supposed to be less than .5 amps. If you set your multimeter to amps, detach the negative battery cable, and then hook the multimeter to the detached cable and to the negative terminal, you should be able to see how much the battery is being drained.

I also remembered another thing. The problem might not even be electrical because, suppose the battery problem is coincidental. What I mean is, suppose for instance the fuel pump were bad, and the battery drained only because you cranked it so many times trying to start the car.

Of course if you need to know whether the battery is presently drained, just set the multimeter to volts and go by this chart:

Voltage State of charge
12.60 100%
12.40 75%
12.20 50%
12.00 25%
11.80 0%

I re-read your post. I guess I overlooked the part about the meter you hooked up. I suppose my advice was stupid since you said the meter proved the battery drain. Sorry about that.

I believe a very slight battery drain is normal. However, if youre suspicious thats there's a short somewhere. Try the following:

disconnect the negative battery terminal

using the leads of your amm meter put it in the circuit...one on the terminal and one the battery

Make sure the car competely off

if the reading is .1 amps or higher (dont remember exactly), then there's probably a significant drain.

Have a friend pull the fuses out one by one to see which circuit is sucking the juice.

Note: make sure when you see the reading that no lights are on, hood light, interior lights, etc...