It has been raining all week and my car won’t start. It has a new alternator and battery. However, the car is old and leaky and I just noticed that the the negative terminal wire was in a small puddle of water where it bolts to the frame under the hood. Could this be the reason for the battery losing charge? Pardon my ignorance.
No. Water leaking into the electronics anywhere might be the cause.
If the terminal isn’t making good electrical connection, the alternator CAN’T charge the battery. Loose the terminal hold down bolt and re-tighten. This should give a better connection. Another way to check the connection is with an electrical multimeter (voltmeter).