Guide 2: Upgrade: Reverse Voltage Protection for CONGA - ROOMBA Robotic Vacuum Battery Tester.

ID: 169692

Description:

Steps:

  1. PART 2, IMPROVEMENT OF THE ORIGINAL DESIGN: This Guide is a continuation and performance improvement of the dead battery tester presented in the Guide: https://es.ifixit.com/Gu%C3%ADa/Comproba...
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  2. Original outline we are starting from.
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  3. Final, improved schematic, adding a protection diode, resistance, and a red LED indicator for the fault.
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  4. The first improvement included in the circuit has been to protect the voltmeter with a Schottky diode, to prevent an incorrect reverse voltage from reaching the voltmeter, since the diode will not allow voltage to pass in the event of a reverse voltage.
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  5. The second improvement is the indicator light, a RED LED, which indicates when it is turned on that we have a polarity reversal; the LED is connected in reverse so that it only lights up in the presence of reverse voltage. I have tested various resistors so that the LED glows less brightly and does not burn out when faced with high voltages of 14 or 16 V.
  6. Example: When powering at 12 V with a 1k Ohm resistor, 1.923 V reaches the LED, which is very close to the limit.
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  7. With a 4.7 kΩ resistance, less voltage reaches the LED, allowing it to withstand a voltage greater than 12 V.
  8. Example of various resistances with which tests have been performed.
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  9. Red LED diode soldering process.
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  10. Wiring installation process.
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  11. LED and 4.7 kΩ protection resistance, plus wiring installed.
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  12. Tester test with correct 12 V direct voltage (RED LED OFF, OK).
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  13. Testing the tester with 12V REVERSE VOLTAGE, the voltmeter does not turn on, while protected by the Schottky diode, the red error LED is lit, warning us of the voltage reversal.
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  14. View of the final assembly with DYMO labeling.
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  15. DIY tool for checking robot vacuum dead batteries, by measuring the battery voltage and applying a load to the dead battery to verify its true effective voltage.
  16. A very useful design that we use regularly at Repair Café Palma.
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