This started as way to possibly extend the battery life of my DeWalt crossline laser. The laser takes 3 AA batteries in series, for a total of 4.5 volts. I replaced two of the AA's with 14500 cells. In the third space, I put an LM7805 (to be replaced with a switching regulator when it arrives) inside of an AAA to AA adaptor shell. I soldered the output of the regulator to the positive of the dummy cell, the input to the negative, and a wire from the bottom to the negative of the tool that is attached to the ground of the regulator. Certainly not the cleanest, but It works, inspite of being a half volt above nominal. With no heatsink or airflow, the linear regulator gets pretty warm (33º C) after 10 mins of continuous use, so I'm looking forward to getting a mini switching regulator. This will increase the efficiency, and ultimately the runtime of the tool.
Components
1×
AAA to AA battery adaptor
It's basically a plastic shell that allows you to use an AAA battery in place of an AA in a pinch
1×
LM7805
Power Management ICs / Linear Voltage Regulators and LDOs
1×
wire
2×
14500 lithium cells
3.7v Lithium cells that are the same size as AA batteries
Linear regulators, such as 7805, to be efficient and precise need 1.5V more at the input than the output, this is a lost voltage and energy as well. I think one 14500 battery would be enough using a converter to give the 4.5V asked by the device.
I don't understand, one 14500 cell is only 4.2v max. The linear regulator was for proof of concept, the excess voltage is coverted into heat essentially. A switching regulator will not have the same issues, and will be far more efficient while achieving the same goal.
Linear regulators, such as 7805, to be efficient and precise need 1.5V more at the input than the output, this is a lost voltage and energy as well. I think one 14500 battery would be enough using a converter to give the 4.5V asked by the device.