Ok, so your Stingray SHOULD work without the battery.
Essentially, the preamp is boost only, so if there is no battery the bass just swaps to passive.
If you generally run the bass without any EQ boost, per my understanding there should be little to no tone difference with our without a battery.
If the preamp is working properly, and you add a battery in, the EQ knobs should have a drastically more noticeable affect on tone. If they do not, then its possible your preamp is just broken and does not work.