Battery is dead again after putting a new.

DETAILS! Right away? Over night? Do the head lights work?

How long does this take? Does everything work normally when you first connect the battery? If the engine cranks and runs after charging the battery, measure the battery voltage to see if the charging system is working. The voltage must be between 13.75 and 14.75 volts.

If everything is dead now, measure the battery voltage right on the posts. If you find close to 12.6 volts it is fully charged and we have to look for a bad connection.

That would indicate there's a drain on the battery but I still would do the charging system test. You could be running on just the battery. Also, if the generator has one bad diode, it will only be able to produce exactly one third of its rated output current. That's only 30 amps from the common 90 amp generator and that is not enough to meet the needs of the entire electrical system under all conditions. A load test will identify that by the low current and "ripple" will be very high.

If the charging system is okay, charge the battery with a home charger for an hour on a low setting. Verify the lights work, then if the battery is dead again in a few days, something is draining it. The first thing I look for is an aftermarket radio that is wired wrong. If you have the time you can pull fuses to see which circuits are responsible. To do a parasitic current draw test gets a little involved compared to years ago due to the many computers that have to time out and go to "sleep" mode. You'll generally need to get a mechanic involved for that.