When the ICE car doesn't start

January 25, 2024

One day, the car that my mom drove refused to start. Since it was an old car, I guessed that the battery voltage was likely too low.

  1. I lifted the hood and pulled the lead-acid battery out and took it into the garage to charge overnight. The next morning, the voltage was about 13.8 V, which seemed pretty good for being nearly three years old.
  2. In the afternoon, I checked the voltage again and it was now at 12.5 V. Upon returning to the car, the voltage lowered a bit to 12.3 V. Trying to start the car again did nothing.
  3. It is possible that the starter and/or the alternator could have problems. The electric starter is what initiates the internal combustion engine and that is the spark that one hears as the car is failing to start. Alternators convert mechanical energy to electrical energy with alternating current (go figure), and it's actually used to recharge the battery and power the rest of the car's electrical system while the engine is running. (Interestingly, before the 60s, most ICEs used commutators instead.)
  4. Upon attempting the start the car again, this time with the multimeter in place, I saw the voltage quickly drop down to 8 to 9 V. It is also possible then that the battery is unable to provide enough current to start the car.

It seems that the only way to be sure of the root of the problem is to use another lead-acid battery to confirm whether or not it's the old battery's problem (and I suspect that it is). We shall see.