ok, i did some searching on AAC and didnt find anything that directly answers my questions.
i am building a large clock (4ft x 4ft). the movement is high-torque quartz unit that is powered by a single C battery. i wish to make the run time much longer. so my idea is to add two more C holders and parallel all 3 batteries. sounds simple enough, but i wish to take it a step further. this clock is big and i do not wish to take it down to change the batteries. i was thinking of using NiMH batteries and building a crude battery charger circuit so when batteries dies i can use a wall wart to charge the batteries back up, etc.
i was thinking of a auto-off circuit. something real crude and simple. attached schematic shows my 1st stab at it. would this work as a auto-off when bat voltage reaches ~1.5v? figured the zener would be 2.2v (1.5bat + 0.7scr). as the battery gets closer to 1.5v the current should drop off enough for the scr to kick off?
i'm not even sure if NiMH is right for this application. would NiMH self discharge too fast and i would find myself re-charging often? perhaps sealed lead-acid or lithium-ion would be better? i know lith-ion cell is ~3.7v so i would need a low loss regulator to feed the movement, perhaps defeating my goal of long battery life....?
any thoughts or suggestions?
i am building a large clock (4ft x 4ft). the movement is high-torque quartz unit that is powered by a single C battery. i wish to make the run time much longer. so my idea is to add two more C holders and parallel all 3 batteries. sounds simple enough, but i wish to take it a step further. this clock is big and i do not wish to take it down to change the batteries. i was thinking of using NiMH batteries and building a crude battery charger circuit so when batteries dies i can use a wall wart to charge the batteries back up, etc.
i was thinking of a auto-off circuit. something real crude and simple. attached schematic shows my 1st stab at it. would this work as a auto-off when bat voltage reaches ~1.5v? figured the zener would be 2.2v (1.5bat + 0.7scr). as the battery gets closer to 1.5v the current should drop off enough for the scr to kick off?
i'm not even sure if NiMH is right for this application. would NiMH self discharge too fast and i would find myself re-charging often? perhaps sealed lead-acid or lithium-ion would be better? i know lith-ion cell is ~3.7v so i would need a low loss regulator to feed the movement, perhaps defeating my goal of long battery life....?
any thoughts or suggestions?
Attachments
-
45.2 KB Views: 44
Last edited: