{"id":60093,"date":"2021-02-07T01:13:52","date_gmt":"2021-02-07T06:13:52","guid":{"rendered":"https:\/\/www.engineersgarage.com\/microcontroller-projects-tf\/series-combination-of-batteries-voltage-monitor\/"},"modified":"2023-08-27T11:18:31","modified_gmt":"2023-08-27T15:18:31","slug":"series-combination-of-batteries-voltage-monitor","status":"publish","type":"post","link":"https:\/\/www.engineersgarage.com\/series-combination-of-batteries-voltage-monitor\/","title":{"rendered":"How to measure voltage of multiple batteries connected in string\/array in series or parallel combination with microcontrollers"},"content":{"rendered":"
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Measuring an individual battery voltage or a whole bank of battery using any microcontroller(arduino, microship pic, Avr, Atmega, Intel, NXP, stm32)is an easy task. You can find many tutorials on internet on how to do so. But what about if we want to measure an individual battery connected to a cluster of batteries in series or parallel combination. Now its a hard task to accomplish. But still their are some cleaver ways to do so. In this post i am going to enlist some of the ways through which we can measure individual battery voltage which is a part of series or parallel\u00a0connected string\/array of batteries.\u00a0<\/span><\/div>\n
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Basic and popular battery monitoring technique – Voltage Divider Circuit<\/h3>\n<\/div>\n<\/div>\n
Basic and the most popular individual battery monitoring technique using microcontrollers in practice is voltage divider circuit. In voltage divider circuit two resistors are connected in series and source (battery) voltage is applied across its ends. Voltage is divided against the two resistors according to the resistor ohmic values.\u00a0\u00a0<\/span><\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n
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\"Voltage <\/a><\/p>\n

Voltage divider voltage divided against two resistors<\/div>\n<\/div>\n<\/div>\n
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Why voltage divider?<\/h4>\n<\/div>\n<\/div>\n
Microcontrollers work on 5 or 3.3 volts(From here on we will take in to consideration 5 volt, techniques listed below can also be applied to 3.3 volt microcontrollers). So their pins are also working on 5 volt TTL logic. Voltage higher than 5 volts could potentially harm the pin or may fry the microcontroller. Solar panel, car, ups, generator and back up batteries normally are at 12 volts. Microcontroller can not measure 12 volts directly. So voltage divider is used here to divide the voltage in two half while ensuring that the one half voltage can not increase 5 volts in any scenario(charging etc). This half voltage is feed to microcontroller to measure the voltage.\u00a0\u00a0\u00a0<\/span><\/div>\n
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\"Voltage <\/a><\/p>\n

Voltage divider circuit with formula<\/div>\n<\/div>\n<\/div>\n
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Now lets calculate the values for Rtop and Rbottom. Here we need some important considerations to be taken seriously.\u00a0<\/span><\/p>\n