Replacing old transformer

Hi,I have a RVD2. I replaced the old mechanical doorbell with existing wiring. I was having to charge the battery every 3 days because by then the battery was dead. I figured the transformer wasn't strong enough so I bought a FCHO 24V 40VA Thermostat and Doorbell Transformer. When I took off the old transformer, it had 4 wires, 2 red, 2 white. The reds were connected together and capped. The whites each went to a screw on the transformer.The new transformer just had a black wire and a white wire with no instructions. I connected the white to a red and capped it. I did the same with the black wire. the other 2 white wires from the wall connected to the screws on the transformer.Now, the RVB2 has been reading 23 % power for a day now. Is this correct or did I mess up the wiring?Thanks in advance,George