Battery dies and can't find out why!
 

so my mom and dad have a 1989 Camry that if i fix some parts of it they will let me have it or when they sell it i get some of the money, and the first step is getting it where the battery doesn't die, we put a new (used) battery in it and it started right up, and all of the electronics worked perfectly (as perfect as 1989 can get) put it in the garage, it sat there for a couple weeks before we did anything with it (i wanted to drive it) but it wouldn't start! the headlights weren't left on, no cabin light were left on, the brake lights weren't stuck on neither were the backup lights, we just couldn't find out what was killing the battery, the battery that we had in before the "new" one we were able to jump start it but we had to let it charge for like 5 minute and if the car was turned off it would need another jump start, but now if we try and jump start it when we turn the key absolutely no lights on the dash come on, my parents say that it has to do with the security system

parasitic draw is possible

what was the alternator /regulator input to the battery

were the battery terminals tight and clean

the cable form the positive battery to starter might be corroded

starter motor, its solenoid ,or actual ignition faulty

re check the big fuses in the engine bay

Obtain a volt-ohm-millimeter.

Use the volt meter to check the battery voltage engine off. A charged battery will be around 12.8v. If discharged around 12.2v.

If the battery is OK but lights don't come on if battery jumped check but the battery cables, terminals, etc.

Determine if the battery is being drained when the engine is off. Remove a battery cable and connect the meter terminals between battery and cable. Check for current draw engine and all other electrical items off. There will be some draw but not much perhaps 2-3 milliamps.

A dead battery when jumped should allow the engine to turn over.

If you do get the engine running use the voltmeter to check voltage between battery cables. Should be somewhere around 13.5-15v. If the voltage is the same as the battery engine off, the alt is not working.

Aftermarket alarms can malfunction and drain a battery.

If you find a high current draw when there should be little. Start removing fuses until the draw drops to what should be normal. If you can narrow down the fuse, you can narrow down the problem area.

Check the trunk and glove compartment lights.

A bad alt can not only not charge but drain the battery.

If you don't have time for the above and need to leave the car. Disconnect the battery.