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Old 06-03-2020, 11:47 AM   #11
FC
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Measured voltage just now having not touched the car at all. It was down to 11.6V. It hesitated a little but started up fine.* Measured voltage while running and got 13.9V, so I guess that confirms that the alternator is working. Shut off the engine after just a couple of minutes and battery voltage read 12.2V.

*WTF? Why was the battery not able to start my car yesterday after 25 minutes of over 3.5krpm driving? Is that not enough and the return drive did the trick to top it off?

Meanwhile, the battery did drop from 12.05V to 11.59V in 24 hours.

Maybe I should disconnect the battery and track it on its own to confirm it's not some parasitic loss.
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Old 06-03-2020, 11:56 AM   #12
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I go through this every ~2 years. In fact, the replacement unit in my 3-year old Accord is getting close to being ready for replacement itself. The heat in FL kills batteries at a rapid pace. At the point where I have to start paying for new ones, I'll do some research to find out if some brands are more durable in the heat than others. Until then...
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Old 06-03-2020, 01:05 PM   #13
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Measured voltage just now having not touched the car at all. It was down to 11.6V. It hesitated a little but started up fine.* Measured voltage while running and got 13.9V, so I guess that confirms that the alternator is working. Shut off the engine after just a couple of minutes and battery voltage read 12.2V.

*WTF? Why was the battery not able to start my car yesterday after 25 minutes of over 3.5krpm driving? Is that not enough and the return drive did the trick to top it off?

Meanwhile, the battery did drop from 12.05V to 11.59V in 24 hours.

Maybe I should disconnect the battery and track it on its own to confirm it's not some parasitic loss.
That's not a bad plan. But in all seriousness, having the battery tested on a commercial machine (for free!) is worthwhile, too. These machines are really good because it's critical to limit warranty replacements.
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Old 06-03-2020, 01:07 PM   #14
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That's not a bad plan. But in all seriousness, having the battery tested on a commercial machine (for free!) is worthwhile, too. These machines are really good because it's critical to limit warranty replacements.
Yeah, I'll do that anyway. And thanks for the heads up on those. It makes sense , to your point, otherwise they'd be exchanging batteries all the time right before the warranty runs out or new batteries obtained simply to rule out the battery.
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Old 06-07-2020, 12:22 PM   #15
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Follow-up: Battery, all on its own, dropped to 11.6V again after 24 hours - the same value as when it was connected to the car. So I think I can rule out parasitic losses as the main culprit. A day later I reconnected it (did not measure voltage) and tried to start it and it felt just like at the Hospital (seemed just a little low). I jumped it with the LR4 without starting the LR4 (I know, not ideal) and it fired up perfectly and I drove it to run an errand.

Just now I took the battery to Autozone to have it tested and the guy came back with a new battery without checking anything. I guess that's that. We'll see if I have issues again. New battery measures 12.78V. Have not started or driven the Miata yet.

EDIT: Can I just say how nice and simple is dealing with the battery on the Miata? All the new fancy cars have all this crap and programming and other nonsense and they are difficult to get to. It took me literally 1 minute to drop in the new one.

Last edited by FC; 06-07-2020 at 12:34 PM.
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Old 06-07-2020, 12:49 PM   #16
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Sadly I was stuck in a stretch with several speed humps in front of the hospital where I had to go.
Forget the battery, what are you doing at a Hospital ... every ok ?
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Old 06-07-2020, 01:38 PM   #17
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Forget the battery, what are you doing at a Hospital ... every ok ?
Thanks for asking.

I'm ok. It's about my son. I had to drop off a specimen for analysis. He's got yet another ongoing symptom we are trying to find a cause for, but right now the specialist is not too worried.
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