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Old 12-21-2017, 01:03 PM
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smj999smj smj999smj is offline
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Originally Posted by mikeinFL View Post
I found that after driving a while the battery charges up to 12.88v area. And with no load will drop back to 12.6 range overnight. Is this normal for a battery?

I tested the alternator at 2000 RPM, lights and AC on: 14.51 steady volts.
The battery isn't charging "up to 12.88" after driving, it's that the battery voltage was charging at 14+ volts and now that the engine is shut off, the static charge of the battery is still elevated from being charged at 14+ volts while driving and it needs a little time to settle back down. This is perfectly normal. Usually anything around 12.2-12.6 volts (static charge) is perfectly acceptable. Charging system voltage can range from 13.2-15.5 volts and be within range, but most late model Nissans tend to sit in that 14.4-14.7 charging volts range. Btw, charging system voltage should be tested at idle and at 3000 RPM, with both loads "on" and loads "off." It's also a good idea to check the battery cable connections to make sure they are clean and tight whenever there are electrical issues. Some batteries, especially those made by Johnson Controls (which makes about half of the automotive batteries on the market), are made with smaller diameter battery post than they used to be years ago and this causes a lot of poor connection issues.
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