Guide 5: Testing the dead battery of Roomba, Conga, and similar robots, 3 Methods.

ID: 186356

Description:

Steps:

1. A Robot Roomba battery model, which is easily replaceable by removing the 2 screws from the bottom cover; it is simply inserted into the compartment.
2. Typically for robot vacuum batteries, the model, size, and connection connector—or lack of a connector as seen here—can vary, but in almost all cases, their voltage is around 14.4V.
3. The battery is the cause of 90% of typical failures in most robot vacuums; batteries support a specific number of charge and discharge cycles, and their battery lifespan ends for several reasons:
4. Having exceeded the X number of charge and discharge cycles that the cells can tolerate.
5. Battery aging due to the passage of time.
6. Long periods of disuse where the battery voltage drops well below a recharge threshold, and the charger no longer recognizes it because it checks the battery's status before starting the recharge.

7. Measurement of the dead battery with a voltmeter is a test that often does not provide the actual voltage; it gives an open-circuit voltage (with nothing connected) which can be between 10 and 13 V, but it is not the actual voltage with a load connected. For that, you need to use, for example, a 12 V automotive light bulb.
8. In this document regarding another robot, I explain the test using a voltmeter.

9. Check with a homemade tester, that I have built. With it, we have a voltmeter and test resistance on the same board, which makes testing much easier.
10. Without pressing any of the buttons, it gives us the battery voltage; in this case, it was at 6.19V, so it is already bad from the start, upon pressing to connect one of the discharge resistance.
11. Photo 2 and 3: The voltmeter turns off, so the battery does not support any connected load, Dead Battery, since it is well below the recharge limit.

12. Testing with a 12V, 21W automotive turn signal bulb, or an automotive headlight bulb, either filament lamp or halogen, in my opinion, this is the best and most conclusive test for the real condition of a cleaning robot battery. If the bulb does not light up, the battery is dead; to pass this test, the bulb must light up at almost 100%.
13. Another bulb model, very easy to make and which I use very often for these tests.
14. Another example that can serve as a guide regarding automotive bulbs.
15. I use automotive lamps because they are easy to obtain; another option would be to use ceramic electronic resistance, like in the tester in Step 3, or a 12 V DC motor with a consumption of up to 4 Amps maximum.

16. Testing the dead battery with a homemade tester, it is very simple, although it may not seem like it, it is nothing more than a voltmeter and 2 load resistors to apply consumption to the dead battery depending on whether one, the other, or both are pressed, 2 pushbuttons and 2 resistance + 2 diodes that indicate that we are pressing to activate a resistance.
17. The entire step-by-step process is here:
18. Another document with an improvement I added later, which prevents the voltmeter from burning out if we power it in reverse.
19. The clamping of the clips to the dead battery is done with neodymium magnets, you have it explained here:

20. Just as a curiosity or additional information, the 2 top terminals located next to the + and - battery terminals have no electrical continuity with + and -, they are isolated, they are the temperature probe terminals and measure approximately 11k7 ohms 11700 ohms at an ambient temperature of about 21ºC.

21. Check that there is no electrical continuity between the upper terminals of the temperature probe and the + and - terminals, (No reading)
22. END of the Guide: Be sure to visit the section dedicated to robot vacuums: