MeganRV, I know everybody is throwing advice at you, but I have a little bit myself. If your battery(s) are going dead in 24 hours, one of two things are happening.
1) You have the wrong batteries, possibly. Starting batteries should be 12 volts, and for a pusher, there should always be two. If you replaced them with anything else, might want to look at that as the problem.
2) If you are losing all charge, a trickle charger is not going to be anything more than a band-aid on a shark bite. There is a short in your system somewhere draining the battery(s) if this is true. Find that short and fix it. A qualified RV tech should be able to find it in just a few minutes. Now, repairing it could take quite a bit longer, depending on where it is, and how accessible it is also.
I was a RV tech after I retired from the military, I wanted to work on something else other than airplanes for a while. So I did 10 years, and loved it. Good luck with your issue, and let us all know here what it is when you find it and figure it out.