I don't know what you are doing with your diagnosis. You are disconnecting your battery because?
And when it dies I presume you reconnect the battery to start it again? And it won't start after a few days. Is that with the battery disconnected all the time? Connected all the time?
It just isn't clear to me what your conclusion is about your alternator. I mean if you start the vehicle and disconnect the battery, it won't get charged. So reconnecting it you are re-starting with a weaker battery the next time.
Normally with battery connected this is what I check.
Start the car, what does the battery voltage measure.
Battery voltage before starting the car. Should be around 12.5V.
Start car it should be 13.8 V to 14.5V range. That would be charging the battery. If it is low then one of a few things are at play.
1) Bad electrical connection between alternator and battery. This can be positive or
2) No power to the field coil on the alternator. Needs that to start power.
3) Bad battery. If the battery is so bad it will take all the energy the alternator puts in and not take a charge. A very depleted battery may cause a low voltage for a bit but voltage should climb as it charges.
4) Bad alternator
5) Depends on alternator, but if there is a separate regulator it may not be alternator but the regulator.
If the voltage looks good, and battery has charged, if you turn it off, what does the batter voltage drop? It should be down around 12.5V again.
You can disconnect the battery and connect and use a multimeter to measure current draw when vehicle is off. There is usually some small amount. I don't know exactly what is normal. An amp is way too much. Somewhere down less than a 100ma, I would worry about 100ma though. If current is high with key off then you need to pull fuses or disconnect things till you identify what circuit it is. I had a car like this. No problems if I drove it daily, but if it sat a week or two the battery would be drained. It was pulling excess current in the accessory circuit.
