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For scale. Range is ~11.6 to 13.6. The time between the two comments (MIL on and multiple backfires) is three seconds.
Some Kmanager images showing voltage fluctuation. Data points are ~10/second. Vertical dotted lines are 10 seconds. Wondering if this is normal batt voltage. First time looking at this kind of data. Someone suggested prob (misfires, flasking CEL, generally running awful) is a low batt issue.
low battery is easy, plug a charger and fully charge, then test again
but does the plot even suggest that low battery is an issue? and if the alternator is working and the battery is good, why would it be low (2nd question is rhetorical)?
I have a good battery in my other civic; i'mna put it in and see I'd the charge range is the same...
What's the minimum/maximum battery voltage you see? Some fluctuation is normal. If the vertical dotted lines are 10 seconds apart, that seems like too much. For reference, here's a snip of mine. Bottom of the chart is 10V, top is 15V. I had issues with my original 300k+ mile RSX Type S alternator so I pulled a base RSX one with unknown miles from the junkyard. Sometimes it behaves (like you see here). Sometimes it fluctuates enough I can see the headlights dimming and get brighter.
Oh, Wow, Brotato! Thanks for the comparison. My voltage regulator must be bad...if there aren't other issues. I've read elsewhere people say their voltage fluctuates between ~12 and ~14, so I thought that my 11.5-13.5 might be normal--guess not.
A bit bigger clip showing a few minutes worth. You can see voltage drop to 12.3V, it appears the alternator shut off at this point. I think this happens occasionally when conditions are met, I don't know if that was the case. Highest voltage I'm seeing is 15.4V spikes. Like I said, this was with a junkyard base RSX alternator that I am replacing. I would agree your voltage fluctuations are not normal.
