I have a 2008 Chevy trailblazer SS. I have a problem that it won't start when the weather drops below 55. Most of the time a jump start will work. NO problems at all if the weather is warm.

they work because they draw absolute minimum power to operate
when you hit the starter it draws 450 amps
so consider this
your battery registers 12 volts and when you switch all the lights bells and whistles on it still registers 12 volts but with a perfect battery when you hit the starter , that voltage drops to 10.5 volts while the starter is engaged
if you have a weak battery the start voltage drops even more to less than 8 volts
now all the power is diverted to the starter and there is nothing left for the electronics and ignition
By adding a jump battery to the system, it gives the full voltage to the battery , starter and ignition system and so it starts
so what do you get from this --- batteries have no guaranteed service life ( that is why there are battery warranties) most batteries fitted to cars are too small in capacity to allow for any deterioration of cells ( most are around 400 ccs where a 500cc is better) and most important point cold weather reveals all flaws in batteries they work because they draw absolute minimum power to operate when you hit the starter it draws 450 amps so consider this your battery registers 12 volts and when you switch all the lights bells and whistles on it still registers 12 volts but with a perfect battery when you hit the starter , that voltage drops to 10.5 volts while the starter is engaged if you have a weak battery the start voltage drops even more to less than 8 volts now all the power is diverted to the starter and there is nothing left for the electronics and ignition By adding a jump battery to the system, it gives the full voltage to the battery , starter and ignition system and so it starts so what do you get from this --- batteries have no guaranteed service life ( that is why there are battery warranties) most batteries fitted to cars are too small in capacity to allow for any deterioration of cells ( most are around 400 ccs where a 500cc is better) and most important point cold weather reveals all flaws in batteries