This invention relates to a method and device for controlling the charging of the battery of a motor vehicle, more particularly, though not exclusively, a two wheeler or three wheeler motor vehicle.

In the electrical system of two wheeler or three wheeler motor vehicles (example: motorcycles, scooters, autorickshaws) the batteries are charged from the generator unit called the magneto. The magneto has two major parts the stator and the rotor. The magneto rotor is connected to the crankshaft of the engine and the stator coil is fixed to the engine crankcase. Whenever the engine crankshaft is rotating the magneto produces an AC voltage depending upon the RPM of the engine. This generated voltage reaches up to 100V. Since all electrical systems of two wheelers and three wheelers are 12V AC or DC, the output of this magneto is regulated to a voltage around 14V AC or DC. Accordingly, a regulator cum rectifier unit (RR unit) is introduced in between the magneto and the electrical loads, such as, the horn, battery among others. The RR unit has two parts namely the regulator and the rectifier. The regulator, regulates the AC voltage from the magneto to a voltage of 14V AC to head lamp, tail lamp, among others. The rectifier unit rectifies the AC voltage from the magneto and regulates it to a voltage of 14 V DC, which is used for battery charging.

As shown in fig.1 there are 2 inputs and 2 outputs for the regulator. The two inputs are lighting input (LI) and charging input (CI) and two outputs are AC output and DC output. Both charging and lighting output of the magneto (M) are fed to the regulator cum rectifier unit (RR). Regulator cum rectifier unit (RR) regulates the AC voltage to 14 V (approximately) and rectifies and regulates the AC voltage to DC voltage of 14 V (approximately). Regulated AC voltage is supplied to bulb load (BL) such as the head lamp, tail lamp among others and rectified and regulated DC voltage is fed to bulb load (BL) and to battery (B) for charging.

Over charging of the battery results in battery bulging, acid spilling out of the battery and under charging of the battery expedites battery draining. The known system above-mentioned does not control the battery charging current. There is no cut off provided whenever the battery is fully charged. There is no boost charging whenever the battery is drained. There is no indication available whenever the battery is fully drained and needs replacement or reconditioning.

This invention proposes a device for controlling the charging of the battery. The device will always monitor the state of charge of the battery and enable or disable the charging output with respect to the state of charge of the battery. Whenever the state of charge of battery is > 95%, charging output is disabled.

If the state of charge of the battery is less than 80% then boost charging input is activated and the battery charging will be faster. Boost charging input is activated whenever

• The throttle is reduced or
• The vehicle speed is decreased or
• The engine RPM is decreased or
• Either of the brakes is applied.

During the boost charging the entire charging output power from magneto is fed to the battery. Since the state of charge of the battery is continuously being monitored there is no possibility of over charging or under charging of the battery.

When the state of charge of the battery is less than 5% and if the state of charge does not improve within 10 cycles of boost charge, then the device gives an indication to the user for battery replacement or reconditioning.

As shown in Fig.2 there are 8 inputs to the charging control device (CCU) and 3 outputs. The lighting input (LI) is regulated to 14 V (approximately) and supplied to the AC output (ACO). The charging input (CI) is rectified and regulated to DC output 14 V (approximately). Whenever the DC output (DCO) pin is enabled, battery state of charge input provides the state of charge of battery to charging control unit (CCU) always and whenever the state of charge. (SOC) of battery is less than the predetermined value, the charging control unit (CCU) gives indication to the customer for battery replacement. Whenever the state of charge (SOC) of battery is less than the predetermined value charging control device (CCU) senses any one or the combination of the inputs such as throttle position signal (TPS) or throttle switch signal (TS), engine RPM, brake switch signal (BS), vehicle speed and the boost charging input (BSI) is enabled according to the conditions met. From the foregoing description it will be appreciated that various other embodiments are possible without departing from the scope and ambit of this invention.

We Claim:

1. A method of controlling the charging of the battery of a motor vehicle comprising the steps of sensing the battery charge and cutting off the charging output whenever the battery charge rises above a first predetermined value; resuming the charging output whenever the battery charge falls to or below the first predetermined value; boost charging the battery whenever the charge falls below a second predetermined value less than the first predetermined value; indicating that the charge has fallen below a third predetermined value, less than the second predetermined value, but has not increased within a predetermined number of cycles of boost charging.

2. A method as claimed in Claim 1 wherein the first predetermined value is 95 %.

3. A method as claimed in Claim 1 or Claim 2 wherein the second predetermined value is 80 %.

4. A method as claimed in any one of the preceding Claims wherein the third predetermined value is 5% and the predetermined number of cycles of boost charging is 10.

5. A method of controlling the charging of the battery of a motor vehicle substantially as herein described with reference to, and as illustrated in, the accompanying drawings.

6. A device for controlling the charging of the battery of a motor vehicle comprising means for sensing the battery charge and cutting off the charging output whenever the battery charge rises above a first predetermined value;

resuming the charging output whenever the battery charge falls to or below the first predetermined value; boost charging the battery whenever the charge falls below a second predetermined value less than the first predetermined value; indicating that the charge has fallen below a third predetermined value, less than the second predetermined value, but has not increased within a predetermined number of cycles of boost charging.

7. A device as claimed in Claim 6 wherein the first predetermined value is 95 %.

8. A device as claimed in Claim 6 or Claim 7 wherein the second predetermined value is 80 %.

9. A device as claimed in any one of the preceding Claims wherein the third predetermined value is 5% and the predetermined number of cycles of boost charging is 10.

10. A device for controlling the charging of the battery of a motor vehicle substantially as herein described with reference to, and as illustrated in, the accompanying drawings.