I am currently modifying a wireless video door phone system with remote door release system, for use with a walking frame, for my elderly mother in-law, who lives alone. The 7"monitor runs a 5v 1a DC plug pack normally, but I have used a 6v SLA battery and dropped the voltage to suit. (which works great) The problem lies when the battery voltage gets low around 6v, the voltage dropping circuit components reach very high temps while the unit is powered to normal use. (burning the components, causing smoke and blistering!) I have also setup a bi color LED to turn red at 6.1v, but is difficult to see and I can't seem to power a micro relay from it.
I was considering a low voltage cutout switching module, but 6v modules seems hard to get or to build with my limited knowledge (kits are one thing, designing and building from scratch is out of my league). Ideas are appreciated. 12v has been considered and is probably my next logical step, as 12v systems seem more available, but efficiency seems to go down and battery weight goes up (to use the same ah capacity). System use is 1A @ 5v DC, standby 300 ma. current battery size 6V 12AH (8 lasts a day) charge rate once a day (over night)