Electronic – How to check what is the percentage of charge in the lead acid battery

batteriesbattery-charginglead-acidmeasurement

http://www.allbatteries.co.uk/media/pdf/AMP92108_FR.pdf

I want to know how much percentage of the battery charge is left without buying any fancy equipment to measure it.

Best Answer

That looks like a lead acid battery with 2 cells. Luckily, assuming a relatively healthy battery you can get a rough idea of the charge level by just measuring the open circuit voltage.

Here's a table of values for some rough voltages to expect (computed using value from here)

100%: 4.22V
75%:  4.15V
50%:  4.08V
25%:  4.02V
0%:   3.96V

If you want to go more in depth, I would recommend reading this page, as well as the links inside that page. The short answer is "it's complicated", and specialized equipment is probably the best answer.

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