Good Day. I'm a graduating student and need a help regarding with my thesis, my final project, in college. Here's one of my problem in my project.

My project is using a Lead Acid Battery and Microcontroller (Arduino) what I want to do is when the Lead Acid Battery is going to be empty or about 10% of its battery capacity I need that to be an input in my Arduino. I've research sensors or circuits that can be input battery capacity in my arduino but can't find anything. Anyone there can help me? Please reply.

 

There is no single sensor that will provide this information. The true remaining battery capacity depends on many variables such as; initial charge, voltage, number of previous charge/ discharge cycles, age of the battery, temperature, rate of self-discharge, load etc. The best you can do is devise an algorithm which takes all these into account and estimates the remaining capacity. The manufacturer should be able to provide discharge curves which may be useful but these will be for a new fully-charged battery at a particular temperature and at a constant current.

 

Thanks for your reply. Your reply make me sad because upon reading it, it just show how difficult to solve my problem but before I just want to share an idea. A while ago I've seen a 12V Lead Acid Battery Low Voltage Indicator

here's the link http://www.electroschematics.com/tag/battery-indicator/

the concept of the indicator is

The BC557 PNP transistor controls the lighting of the LED. The BC557 transistors’ base is biased by the 10V zener diode. As long as the battery voltage stays above 11.6V, the zener keeps the base of the BC557 transistor high. When the battery becomes discharged, the zener stops conducting and the base bias goes low, and BC557 begins conducting, and the LED alerts you to the low battery voltage. You can use a variable resistor to fine tune the low voltage indication, and/or use a set resistor when you have a good value figured out.

based from what I know Lightning of the LED light can be an input to my Microcontroller (arduino). What do you think?

 

It would be good to read up on batteries in general. You are not the first to want to do this or something similar. There is a plethora od information at the Battery University web site and here in particular is a link to their section on Charging Led Acid batteries.
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

And here on a battery fuelguage - http://batteryuniversity.com/learn/article/the_battery_fuel_gauge

 

based from what I know Lightning of the LED light can be an input to my Microcontroller (arduino). What do you think?

You don't need any extra active circuitry if the micro-controller has an analogue input. Use a resistive voltage divider to scale the battery voltage to within the range of the A-D converter and measure it directly.

 

There is a *huge* difference between detecting a low battery condition and estimating remaining capacity or remaining discharge time.

 

There is a *huge* difference between detecting a low battery condition and estimating remaining capacity or remaining discharge time.

Just last week, I met a car battery that was discharged. Its behavior about accepting charge from my battery charger convinced me that the battery is down to about 20% of its original capacity. This illustrates the idea that a, "remaining capacity" measurement is not obvious. You have to monitor the behavior of the battery during charge and discharge cycles to determine a guess about its capacity today.

 

A while ago I've seen a 12V Lead Acid Battery Low Voltage Indicator here's the link http://www.electroschematics.com/tag/battery-indicator/...

The concept of this circuit is no more than can be done any time with a Digital Multimeter. It is nothing but a voltmeter.
If you read the BatteryUniversity links, you will find that there is only a weak correlation between battery voltage and battery capacity.

 

You don't need any extra active circuitry if the micro-controller has an analogue input. Use a resistive voltage divider to scale the battery voltage to within the range of the A-D converter and measure it directly.

You can get better resolution from the ADC by using a zener diode to drop a proportion of the voltage.

 

Hello Guys thanks for your replies

Lead Acid Battery Capacity is solve. Since I only need to show what is the remaining capacity of my Lead acid Battery. I will just buy a 12v Lead Acid Capacity Tester from ebay.
here's the link http://www.ebay.com/itm/Battery-Cap...-Lead-acid-Lithium-LiPo-LCD-New-/121532309778

The help I need now, is a connection to my lead acid battery and microcontroller. like the voltage reading to be ang input signal to my microcontroller. Anyone can help me?

 

Hello Guys thanks for your replies

Lead Acid Battery Capacity is solve. Since I only need to show what is the remaining capacity of my Lead acid Battery. I will just buy a 12v Lead Acid Capacity Tester from ebay.
here's the link http://www.ebay.com/itm/Battery-Cap...-Lead-acid-Lithium-LiPo-LCD-New-/121532309778

The help I need now, is a connection to my lead acid battery and microcontroller. like the voltage reading to be ang input signal to my microcontroller. Anyone can help me?

I don't think the eBay item can do what you want.

To get a simple voltage reading, you will need a voltage divider. (2 resistors in series)

 

I don't think the eBay item can do what you want.

To get a simple voltage reading, you will need a voltage divider. (2 resistors in series)

Hi Bug in my project lead acid battery capacity is different from voltage reading.
I think you are mistaken my explanation

Lead Acid Battery Capacity reading can be read thru that item which will be an output for my device

and What I need now is reading of voltage reading to be an inpout to my microcontroller and I think voltage divider can be an input to my microcontroller

Thanks bug.

Anyone suggest any other options?

 

Hello Guys thanks for your replies

Lead Acid Battery Capacity is solve. Since I only need to show what is the remaining capacity of my Lead acid Battery. I will just buy a 12v Lead Acid Capacity Tester from ebay.
here's the link http://www.ebay.com/itm/Battery-Cap...-Lead-acid-Lithium-LiPo-LCD-New-/121532309778

The help I need now, is a connection to my lead acid battery and microcontroller. like the voltage reading to be ang input signal to my microcontroller. Anyone can help me?

I thought this had been explained earlier (several times), there is no such thing as an add-on battery capacity meter. This ebay device is really just a voltmeter that will tell you very little about the condition or capacity of the battery.

How do you propose to connect this device to the battery and micro-controller? You're the engineering student, you selected it.

 

Hi Bug in my project lead acid battery capacity is different from voltage reading.

That's what we've been telling you for a week.

Lead Acid Battery Capacity reading can be read thru that item which will be an output for my device

and What I need now is reading of voltage reading to be an input to my microcontroller and I think voltage divider can be an input to my microcontroller

If you think that eBay battery tester can read capacity, and provide an output for your device, what kind of output do you think it will have? Current per amp-hour of capacity? A voltage per amp-hour of capacity? Do you believe the eBay battery tester is calibrated to your ADC input? If it is not, how would you correct the output?
Hint: Exactly what bug said.

 

What about there is only a weak correlation between battery voltage and battery capacity did you not understand?

 

I hope this is not too old a thread to wake up but...here's what I use....and I made it.
https://hackaday.io/project/1375-lead-acid-ah-capacity-testerlogger

 

I hope this is not too old a thread to wake up but...here's what I use....and I made it.
https://hackaday.io/project/1375-lead-acid-ah-capacity-testerlogger

Very good, but it doesn't apply to this thread because it isn't what the OP was asking for.