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Alternator & ChargingQuestionCommunity Starter

2008 Honda Accord — battery dies after the car sits for a weekend

DailyEnthusiast399Community StarterMar 31, 20262008 Honda Accord EX-LLong Island
Battery passes a quick test and charging voltage looks normal, but after two or three days parked the car sometimes will not crank. What is the cleanest parasitic-draw test on a modern car that takes time to go to sleep?
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3 replies

FlatSixMechanicish898Community StarterCommunity StarterApr 1, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 2008 Honda Accord so service can see what you saw. Then you'll know the next fork. If they can't show the line item, I assume it's hiding. Not interested in a five-hour wait for a shrug.
UsedCarGarage59Community StarterCommunity StarterApr 1, 2026permalink
That's a good start, but I wouldn't stop there. Try a second charger before blaming the 2008 Honda Accord — site sharing and pack temp change the curve a lot. Then you'll know the next fork. That's the whole play. Wrote this up on my lunch break.
ColdStartWeekend566Community StarterCommunity StarterApr 1, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 2008 Honda Accord charge sessions. That's where I'd start. Had a similar mess a couple years ago and that's what finally sorted it. No warning lights, which is why I'm documenting it.
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