12v fully charged Lead Acid Battery.

[Captain Yoghurtpot]

Quick question for the knowledgable amongst us.
At what voltage is a Lead acid battery 100% charged?
I thought it was 12.6v but will stand corrected.
AND, at what point is the same type of battery at 50% discharged?
Is it 12.2v?
Much obliged
Thanks

 

[Kannon Fodda]

Full charge 12.6V-12.7V (depends on quality of the measurement kit and connectors). Best is ideally across battery terminals without any wiring that could add resistance.

50% is just over 12.0V.

All measured at rest for at least 30 minutes if not an hour.

 

[dunnah01]

Quick question for the knowledgable amongst us.
At what voltage is a Lead acid battery 100% charged?
I thought it was 12.6v but will stand corrected.
AND, at what point is the same type of battery at 50% discharged?
Is it 12.2v?
Much obliged
Thanks

Most sources I've seen are 12.7 & 12.1 after standing for at least 1/2hr with no load.

 

[Captain Yoghurtpot]

Thanks Kannon Fodda and dunnah01 .
Think my battery then is all ok and performing as should.
Thank you for replying.

 

[Kannon Fodda]

Unfortunately voltage is only part of the story. It can appear to have reached a full charge. But with a number of cycles the lead plates will gradually weaken as the chemical reactions of charge and discharge take place. So it takes less overall current to charge or discharge. Sign of a failing battery will be it quickly reaches full voltage and equally seems to get to low voltage in a shorter period of use.

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[Lenny HB]

12.7 to 12.9v if its in decent shape arfter it's rested for an hour.

 

[autorouter]

At what voltage is a Lead acid battery 100% charged?

Different types of battery, all using the same basic lead/lead oxide/sulfuric acid technology, have slightly different voltages for the same charging percentage. Notably, some AGM batteries are 12.8V to 12.9V when 100% charged, where flooded batteries, with liquid electrolyte, are around 12.6V to 12.7V. So you need to specify what type of lead-acid battery if you want a definitive accurate voltage.

 

[Captain Yoghurtpot]

Different types of battery, all using the same basic lead/lead oxide/sulfuric acid technology, have slightly different voltages for the same charging percentage. Notably, some AGM batteries are 12.8V to 12.9V when 100% charged, where flooded batteries, with liquid electrolyte, are around 12.6V to 12.7V. So you need to specify what type of lead-acid battery if you want a definitive accurate voltage.

It's a flooded lead acid battery with liquid electrolyte and I am getting a reading of 12.6v when fully charged after standing for 1 hour, so think all is well.
Thanks for the reply autorouter .

 

[Manic]