My 2012 Grand Caravan won't charge the battery, I have changed the alternator

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. I honestly don't follow why you "replaced the...computer and flashed it". For what purpose? Sounds like you need a new "professional" to check the car out. This is not that complicated. Starting and charging system issues follow the same diagnostic troubleshooting flow chart. First, check the battery to determine it is good and fully charged and able to sustain a load. Second verify all connections are secure, clean and in good condition. Third once the vehicle is started, check charging system output to verify it is sufficient to maintain battery charge while the vehicle is operating and drawing resources from the battery. This means electrical voltage and amperage is sufficient. Finally, you will want to make sure that there is no parasitic draw occurring while the vehicle is off and you are not in it. This means that nothing is draining the battery while you are away from the car. If the battery is low in charge, then the engine will not crank and start. If this is the case, the battery should be checked for state of charge and the ability to sustain a load. If all tests good here, then the starting and charging system should be checked for faults. If the battery is discharged but when charged sustains a load and charge satisfactorily, then there may be a parasitic draw causing loss of battery power over time. Hands on testing is needed to see what is happening. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.