Have you had the alternator tested? Often a bad internal diode can drain the alternator overnight.
my ford ka battery is 2years every morning it is flat even if i have done a 100 miles the day before.
you possibly have something draining the battery when the car is shut off, with the car shut off pull the positive cable off the battery and then just touch the cable to the positive post of the battery and see if you get a spark, if you get a spark you have something electrical draining the battery.
Something is causing a drain on the battery even with the vehicle off and nothing turned on. A good mechanic can do a drain test on the battery to see what may be draining the charge. A dead cell in the battery itself will also cause the battery to go dead. Disconnect the negative battery cable overnight and if the battery is dead the next morning it has a dead cell and must be replaced. If not look for a light that is on or a relay that is stuck.
I have this same problem on a 2009 street bob. Let me know if you find an answer. Mark
Most likely there is something that is draining it. In case it might be the battery itself, disconnect the battery terminals at night. When you reconnect in the morning and the battery is OK, then the problem is in the electrical system somewhere. If the battery is dead then the battery needs to be replaced. Finding the fault in the electrical system can be difficult. Check to make sure all lights go out when the car is turned off. Pulling fuses to see if any stops the drain could help isolate the problem too. Good luck
Either the battery has a dead cell, which will normally drain it overnight, or something is on pulling power from the battery. If the battery has a dead cell it will have to be replaced. The easiest way to determine this is to fully charge the battery and then disconnect the negative cable overnight. If the battery is dead in the morning it has a dead cell. You may not even be able to charge it with a dead cell. If the battery is still fully charged the next morning then you have another problem. Check all the lights on the vehicle. Under hood, trunk, dome, curtorsey, glove box, etc. One of them may be staying on. Also check your brake lights. If you find no lights are on then you may have a relay that is sticking. Can be power windows, locks, seat, etc.
This may be a sign that your battery needs to be replaced. However, there may be other causes as well.
Make sure the battery cables are making good contact with the battery and are clean and tight.
check your battery connectins. you could have a bad ground
well if you do nothing the battery will stay full a long time . and if you leave the light`s on it will be empty the next morning[i speak whit experience] it has happend to me. but the car battery of my car has not been replaced for 190.000 km[117.800miles]
The battery that powers the CMOS and clock (PRAM and clock on a Mac) has died and must be replaced. On a PC this is usually a nonrechargeable coin cell (on a Mac this is usually a rechargeable battery connected with a short cable). Once this battery has been replaced the clock will function normally again.
Something is draining the battery. Possibilities are dome/map/courtesy light, trunk, glove box, under hood light. In rare cases a stuck power window/lock switch. Look at the car in the dark and see what is on. Remove the positive cable and the touch it to the positive post in the dark. If you see a spark something is on.