12V 4 AA Cell Differential Temperature Charger
This project includes a number of improvements over my older Temperature Controlled NICD Charger circuit. This circuit runs on 12VDC, allowing it to be used in a car or from a 12V solar power system. Additionally, a current sensor LED verifies that the cells are receiving charging current. Note that the current sensor circuitry is not shown in the circuit board photo above, it was added to the side of the main board via a small perfboard. 12V, 4-AA Cell Differential Temperature Charger Circuit diagram The current is adjustable in three steps from 100 to 300mA, allowing fast charging of AA, AAA or other small cells. Battery packs from 1 to 6 cells can be charged with this circuit. NiMH and older NiCD cells are supported. The circuit is protected from reverse input voltage and reversed cells. Connections: 12VDC (nominal) power input Connections for the Battery Under Charge Controls: Power On/Off switch Charge Start switch 3 step Charge Current Select jumper Calibrate/[Latch] mode jumper ...