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I have charged a 12V golf trolley battery and get a reading of 13.63V when fully charged. How is this possible when the V should read 12.66V?

JRE
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Philip Oxlade
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    12.66V is strangely specific and overly precise (nobody ever publishes battery voltages to two decimal places.) What told you to expect 12.66V – JRE Sep 27 '21 at 11:12
  • Have you disconnected the charger? – StainlessSteelRat Sep 27 '21 at 11:14
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    A 12V lead-acid battery can't read more than 12.8V when fully charged and disconnected from the charger for some time, but when it is being charged, its voltage can go from 13.2V to 14.5V, depending on its exact chemistry and the charger. So, it is not unusual to have over 13.5V on such battery WHILE IT IS CHARGING, but once it is disconnected from the charger, or the charging is stopped, its voltage goes back down below 13V fairly quickly. If it is kept at a FLOAT voltage, it could be anywhere from 13.2V to 13.8V, though there is gassing above 13.2V in a wet battery. – Edin Fifić Sep 27 '21 at 11:23
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    Does this answer your question? [What should the voltage of a fully charged lead acid battery be?](https://electronics.stackexchange.com/questions/38321/what-should-the-voltage-of-a-fully-charged-lead-acid-battery-be) – Lundin Sep 27 '21 at 11:59
  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. – Community Sep 27 '21 at 14:40

1 Answers1

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It is expected that the voltage of a fully charged, 12 V lead acid automotive battery would be 12.7 V or higher.

In automotive alternators, voltage regulation is achieved through on-off switching of field current between 2 set points (e.g. 13.8 & 14.2 V for a 12V system). Hence the voltage, immediately after charging, would be around 13.8 - 14.2 V.

However, 12-24 hours after charging, the actual resting voltage would settle down to 12.7 V.

vu2nan
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