UPDATE: Just jumped the car again. Connected a meter to the battery terminals. At idle, the reading was 14 volts. Based on what I've seen online, a reading of 14 volts at idle shows the alternator is working??? Any thoughts ya'll can share would be greatly appreciated.

Greetings. I have an 01 S40 w/100k. The car wouldn't start this morning. Jumped it with my wifes car...drove 30 miles, no problems. Later in the day it wouldn't start again. So, I jumped it again. I was driving down the road (daytime) and flashed my lights (via the blinker lever) and the car totally died. NO electricity. Wouldn't start. After an hour, I jumped it again...went to CAP...they tested the battery and said it seemed fine. Got home, and flashed the headlights again...and again, the car instantly died. No electricity to even lock the doors. Any ideas? Alternator perhaps?? I appreciate any words of wisdom.

 

14 volts is good. Charging system is working.
They tested the battery out of vehicle? Cuz it really seems like bad cells. I have seen some VERY strange things happen due to a battery that not only has dead cells that won't hold a charge, but a bad cell or cells. If it was me, I would get another battery and install it with the intent of returning it if it is not the problem. In other words, don't bust it up installing it. If you simply install it, start it, and flash the lights in your garage or driveway you should know right away, correct?