[alexwhittemore]

My 2009 has its original battery. It's got some problems that COULD BE (but likely aren't) ignition related, and it always turns over, but sometimes it labors for a while, especially after I haven't driven it for a week or two. Like, maybe cranks 2-3 times before ignition, where when I first got it, it'd barely turn once.

I brought it to pep boys for a quick load test: it's a 95AH battery, 900CCA. It was measured at 795CCA, but only 12.36V which, by their machine's estimation, is a 55% state of charge. Given that I'd been driving it around for an hour or two that day, it certainly should have been near-full.

I DO have some excess electrical draw on the system - my cigarette lighter sockets are all wired to turn off after 30m of key out, rather than immediately when the car turns off. So that could contribute to long-term deeper-than-normal cycling, but certainly not short-term since-i-turned-it-off-that-day drain.

So Q #1: Is this a normal failure mode/degredation mode for an AGM battery? I would have expected CCA to test way, way lower if a cell was failing, for example.

Beyond that, I've had code 2DEB - "power management network failure" (according to Carly) for a while. I just for the first time looked that up in Bentley and the book says that 2DEB is actually undervoltage or overvoltage. The code first started appearing when I was charging devices off a direct-wired socket I put in my trunk, so makes perfect sense (I also got codes for excessive current draw, which, of course, there was.) But even after clearing those, 2DEB came back without further excessive draw.

So maybe that's related to my typically low SOC?

Question 2: During operation, my system seems to operate at 14+ volts continuously. I didn't scope it, so that could actually be noisy and dropping below 12 with high frequency, but I doubt it. Have you ever had issues with a low SOC causing a rough running engine? I feel like that shouldn't be the case, as long as the alternator is also fully functional.

Basically, I wouldn't feel bad about swapping the battery out, but I don't have much hope that i'll improve any of my car's engine trouble.