Car Wont Start

[MaxMye30]

So i know its an electrical problem, i just have few questions that may help me fix it with the least amount of useless spending and stress.

So my car wouldn't start yesterday, it was about an hour after i drove it home from about a quarter mile away (its rainy here, don't judge) its the battery I'm very confident, but the why is what i want to know.

Some of the facts:
The battery in there was size 51 (bought the car with it and hadn't gotten to replacing it yet) it was obviously too small but the car was starting fine and i haven't had any problems for the 2 or so months I've owned the car.

i installed a sound system and part of that is an amp that draws directly from the battery, I'm wondering if that is whats taking the power from the car, I'm wondering if its drawing power while the car is off, it has the remote wire all connected to it shouldn't be on unless the radio is on. If its just drawing too much power while its on the new battery I'm now kicking my self to go get should solve that... right? or am i going to need a bigger alternator? its not that huge of a system but its far from the stock one.

i really just want my car to start, i rely on it and it would be very nice to not have a problem with it for a few days (literally there has been a different problem with it every day this week).

Does anyone know a lot about car batteries that could explain what is really going wrong because i have been trying to charge the battery that was in the car and it doesn't seem to be working at all. Has the battery just been drained to death and thats all? how can i check to see whats draining power or if anything is draining power? any insight would help thanks!!

EDIT: the battery i plan on buying is size 49, also there is some water in the bottom of the battery tray, i know its cause of the leaky taillight gasket on the battery side, water pools on the battery cover and i frequently empty it whenever i get in and its raining because i haven't been able to replace it yet.

[strad]

Test voltage at the battery with the car running. Quick but dirty, this will tell you if the alternator is putting out (should be around 14). A more sophisticated test is to remove the alt from the car and have it bench tested. This will give you info about amps it's putting out. If it's not charging the battery, getting a new battery is not going to help for long.

As for current draw while the car is off, I haven't had to do that yet (knock on wood lol) so I can't help you.

[Tom D]

as long as the stereo/amp is not wired to a constant hot then there is not a power draw while the ignition is off.

if the total wattage of running the car and stereo is greater then the output of the alternator, then the excess power needed is drawn from the battery. only a higher amperage alternator or a smaller wattage amp will correct this.

if you are depleting the battery charge by running the stereo then you should at least change to a 'deep cycle' battery.

if you are losing battery charge at a high rate while parked and everything is wired correctly and off, then it may be a leaking diode in the alternator. there are several (4 or 5) and if any of them are bad it will drain the battery to ground through the alt.

there are many reasons for a battery not to work properly and one of them is heat. if you have ever charged the battery with a high amp 'quick charger', then the lead plates can overheat, warp and make contact with each other, shorting out that cell.

[MaxMye30]

Ok well I took the battery out of the trunk and charged it for a few days and noticed there was corrosion on the floor of my garage from it and it was leaking sulfuric acid. So obviously that's why it wasn't working but there is still a chance that I'm getting a drain from somewhere in the car so how can I test those things you guys mentioned? Like how much wattage my at is pulling and how to test my alternator? Thanks for the help!

[T77911S]

take the car to advance or autozone, after you get a good battery, and they can test the charging system for FREEEEEEEEEE. (adam sandler voice).