Rev600mod

I have a 1994 chevy 1500 8 cyl 305 pickup. It would start very poorly when it was cold over night. It would make just a clicking noise for 5-8 key turns before starting and it would start perfectly fine if it was warm at night or kept inside. I changed the starter out for a newer one and know it sounds like the battery is dead when it starts and hesitats and turns over very slowly for 5 or 6 turns of the motor. It wasnt doing this before i swapped out the old starter for the newer one.

Anyone have any ideas of why it is doing this now?

Thanks alot