12v low when moving trim with motor not running & when first startup after ski sits

[yogi26m]

I just bought a 1997 seadoo gsx. The ski starts right up and seems to run fine, but if i move the trim when its not running the 12v low flashes at me. It also did this when i started it when it sat for a few days. It goes right off when it starts tho and runs fine. Is this my battery? Will i wreck something if the battery is getting weak? The battery says energizer, so idk if its a good one or a cheap one.