Thermal Controlled battery charger

One way to charge batteries rapidly without abuse is to measure cell temperature and tapper the charge accordingly. The circuit uses a thermocouple for this function. A second thermocouple nulls out the effects of ambient temperature. The temperature difference between the two thermocouples determines the voltage , which appears at the amplifier's positive input.

As battery temperature rises, this small negative voltage ( 1 degree Celcius between the thermocouples equals 40uV ) becomes larger. The amplifier, operating at a gain of 4300, gradually reduces the current through the battery to maintain its inputs at balance. The battery charges at a high rate until heating occurs and the circuit then tapers the charge. The values given in the circuit limit the battery-surface temperature rise over ambient to about 5 Degree Celcius.

Part List :

Resistor
R1_____620K
R2_____43K
R3_____10R
R4_____2K
R5_____0.6R 5W

Capacitor
C1_____1uF
C2_____0.1uF

Diode
D1_____1N4148
D2_____1N4001

Transistor
T1_____2N6387

IC
IC1____LT1001