FAST CHARGER controlled by a 68HC11

Note first the battery to be treated at the center of the figure. It is connected to contacts of a relay. The diagram shows the relay at rest. Under these conditions the battery is in SHOCK . His pole - is grounded and its positive pole to the circuit of constant current discharge. This circuit consists of N-channel MOSFET controlled by the TM2 IC2B OP amp. The input of this amp + e is at a potential adjustable by the digital potentiometer IC 4. The op amp will therefore act on the conduction of TM2 to pass in R17 to cause sufficient current to equal voltages and e + e-. It is understandable that by adjusting the voltage by e + IC4 is going to vary the intensity of discharge. The adjustable P4 allows the setting of the value of the intensity at the focus.
FAST CHARGER controlled by a 68HC11 - schematic

FAST CHARGER controlled by a 68HC11 - img1

If it was left to bear the burden of TM2 only the discharge current, it heats up tremendously. In fact, if you release 12 V 2 A 24 W gives it! It would take a huge radiator! We have resolved the issue by inserting the resistors R13 to R15. These resistors are mounted outside the cabinet. These are models with 25 W radiator. The heat does not win inside the CD1. Moreover, it is possible for riders to easily choose 1, 2 or 3 resistors to accommodate the number of items to unload. Fig. 1 Now note the presence of IC3: this is our precision voltmeter! It is 12 bits, thus capable of 4096 points. We calibrate it to measure from 0 to 40.95 V at 1 / 100 of volts. This converter requires an external reference of 2.5 V. Z is the zener (TL431) which provides. The final calibration is done by P1. In discharge mode, the - batt is grounded by the relay, so the voltage measurement is not a problem. Circuits IC4 and IC3 are SERIAL programming. So the ?C which will manage the mission of these two circuits. IC3 is a MAX1241 from MAXIM. IC4 is an AD8402 (10 k W ) ANALOG DEVICES. Readers interested in the functioning of these circuits may, as we did, download the files of these circuits on the Web sites of these manufacturers. Now to the circuit CHARGE . It is located at the top left of the figure. For charging, the relay switches to work. Consider first the case of charging a...

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