Hello all,

One time last week my car did not start and I had to get it jumped. I own a 2010 E350 4d with 70k miles. I replaced the battery about 5 years ago. I got the battery tested by AAA and he said it was fine so I am not sure what to do.

When I ran the battery voltage I see the following:
Before starting the car engine: 11.4V
When the car engine is on: 14.7-14.9V
After turning off the car engine: 12.1-12.2V

I would also like to add that I have the radio, my phone charger, and my radar detector always on which I realized might be an issue. I also want to point out when I start my car, I feel like it takes slightly longer to start than it would normally.

Can anyone detect a problem here? I want to make sure my car does not die on me or turn off on me in the middle of driving for my safety.

Thank you for your help,
Dan

I am not sure if your 2010 has "smart charging"...
if it does the ECU shuts off ALT during acceleration which can crash enough modules to earn you instant LIMP mode while driving - Don't let that surprise you in the fast lane.

These numbers are too low:
Before starting the car engine: 11.4V
After turning off the car engine: 12.1-12.2V

... battery kaput???

Time for a new battery. 5 years is pretty good.

Do you have sticker on the battery like CCA ? If your readout are matching the number on the battery sticker then you may need charging . I also posted a similar message .
On the other side , 5 years is good for a battery but for a piece of mind a new battery is better idea