A "Problem" Triangle Mystery

Hello, While I was on the road today, my car displayed the red triangle of death, check engine, and a few other dash lights. I pulled off to the side of the road and car quickly died.

Towed to mechanic, voltage read 3.5v, they charged the battery (it seemed to hold a charge they said) and two codes came up: C2300 Actuator system malfunction and C2318 Low voltage error. Mechanics test drove the car and it ran fine after charging the battery. They couldn't replicate any problems and sent me on my way.

I'm about to go on a cross-country move and would be terrified that my car would stop accelerating while on the highway. Any other things I can check to find out what this problem is? Today I used MFD to test the voltage of the battery after not driving for the past 1.5 days, and it was at 11.9 in ACC mode. Also, for context, I haven't driven the car more than a joy ride about 2x/week this winter. Do I need a new battery, or just drive more often, or something else, any more ideas or tests to try? thank you.

 

Thank you for your replies. I purchased the car 6 months ago, so I'm not sure how old the battery is. Is there any other test I can do before replacing to make sure this is the problem? The auto shop said to keep driving and see if the problem happens again, as it could be inverter or something else. That scares me a little with the upcoming trip.

 

Thank you, I will check out the battery to see if I can find a date. There are about 146k miles on the car. Indeed, what would make a battery drop to 3.5v? That is what I am wondering.

 

These are both good ideas. I spoke with some auto shops today and it seems firestone is offering the super start battery for $180 plus $15 installation. thats only a little bit more cost than buying a jump box... sounds like a good deal unless I'm missing something.