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    Reading the voltage between battery terminals in an automated product line

    I am trying to design an automation line for a project in which batteries are tested just off the product line.
    The batteries will be transported via conveyor to a testing jig where the voltage across the terminals is read and relayed to a microcontroller.
    Depending on whether the voltage across the terminals is the required 1.5V or lower, the battery goes on to be accepted or rejected off the conveyor.

    Although I have the actuators and their mechanics sorted, I am struggling to find a method to read the voltage across the battery in a way that can be communicated to the microcontroller.

    Any suggestions?

    Thank you in advance
    Al

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    Re: Reading the voltage between battery terminals in an automated product line

    your distance between voltage measuring point and mc is not known.

    if it is closer , you can have an adc and read the voltage and decide.

    if it is somewhat longer have a separate daq for measuring voltage and send the data to mc.



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    Re: Reading the voltage between battery terminals in an automated product line

    Please put a current load on the battery under test, voltage will not tell you anything about the batteries internal impedance.
    Frank



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    Re: Reading the voltage between battery terminals in an automated product line

    Quote Originally Posted by chuckey View Post
    Please put a current load on the battery under test, voltage will not tell you anything about the batteries internal impedance.
    Frank
    Yes, this is very important. Even batteries with little charge in them will read close to 1.5V if they're not loaded.

    What kind of microcontroller are you planning to use? Many have internal ADCs, in which case the interface is just a couple wires and a load resistor.



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    Re: Reading the voltage between battery terminals in an automated product line

    your distance between voltage measuring point and mc is not known.
    The distance will not be over 150mm

    Yes, this is very important. Even batteries with little charge in them will read close to 1.5V if they're not loaded.
    So let me get this straight, you need a load resistor connected in series in the battery's circuit to determine the voltage across the battery terminals?

    What kind of microcontroller are you planning to use? Many have internal ADCs, in which case the interface is just a couple wires and a load resistor.
    I am using an ArduinoMega which from what I gathered does not have an internal ADC, to be honest it is my first time controlling with a microcontroller, I have only worked with Ladder Logic till now and I was told the Arduino is easier to pick up than other microcontrollers such as the 8051.

    Thanks



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    Re: Reading the voltage between battery terminals in an automated product line

    Hi;
    Even batteries with little charge in them will read close to 1.5V if they're not loaded
    means put some load resistor, so that you have more reliable readings from the battery.
    Something like attached should fit your application.
    Click image for larger version. 

Name:	batt.GIF 
Views:	9 
Size:	4.1 KB 
ID:	66901
    But i am not sure about the dummy load resistor value. What should it be? Other friends may answer.
    On the orher hand PIC series micros have internal ADCs and you can find many examples on PIC programming, ADC peripheral etc.
    Hope helps



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    Re: Reading the voltage between battery terminals in an automated product line

    please note that your saying:

    So let me get this straight, you need a load resistor connected in series in the battery's circuit to determine the voltage across the battery terminals?

    is to be changed as ' a resistor is to be connected across the battery terminals.(it is a load).
    its value depends on the Ah of your battery.

    on which controller , you have many choices. since you are starting now , dont be tempted by the facilities in the mc.

    analyse with caution about the development tools for that controller available and the cost , availability(in free market or OEM only) and finally future exapansion.



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    Re: Reading the voltage between battery terminals in an automated product line

    All DMM works with the same principal they are loaded internally ...

    ---------- Post added at 20:24 ---------- Previous post was at 20:23 ----------

    after loading you may need ADC for giving digitized O/P to micro controller.



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    Re: Reading the voltage between battery terminals in an automated product line

    instead of starting from basics of mc programming and adc capture, i recommend to use a digital multimeter with rs232 or usb interface.

    thro rs232 or usb you can simply read the voltage under your control , say , from a low cost pc and then decide on whether to accept or reject the battery.

    you can just visit

    PROCON TECHNOLOGY - Data Logging Multimeters from $99

    to get an idea and low turnaround time development of your task.



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    Re: Reading the voltage between battery terminals in an automated product line

    Quote Originally Posted by proudgrover47 View Post
    I am using an ArduinoMega which from what I gathered does not have an internal ADC, to be honest it is my first time controlling with a microcontroller, I have only worked with Ladder Logic till now and I was told the Arduino is easier to pick up than other microcontrollers such as the 8051.
    The Arduino Mega does have several analog ADC inputs. The ADC is 10 bits, which will give you about 5mV of resolution with a 5V reference voltage.



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    Re: Reading the voltage between battery terminals in an automated product line

    The Arduino Mega does have several analog ADC inputs. The ADC is 10 bits, which will give you about 5mV of resolution with a 5V reference voltage.
    I know I looked into it and found online tutorials, thanks for the heads up.

    I am about to read a tutorial but from what I gathered it seems as though all that has to be done is to connect the a load across the battery terminals, hook it all up to an ADC (such as the attachment uploaded by emresel) which will have set values through resolution and the controller takes action from there, am I correct or am I missing something?

    Thank you for all you input



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    Re: Reading the voltage between battery terminals in an automated product line

    Can I measured voltage by sensing di/dt?
    IMRAN



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    Re: Reading the voltage between battery terminals in an automated product line

    Can I measured voltage by sensing di/dt?
    Change in current with change in time? This is the first time I'm going to be 'sensing' voltage and the most common way is using an ADC (from the research I carried out and the great feedback on this thread!).
    However I would assume that if you can get a reading of current and you have a known value of resistance, the respective voltage can be found, so maybe it can be used in that way?

    Al


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    Re: Reading the voltage between battery terminals in an automated product line

    DI/DT would not be recommended for battery DC voltage. I would recommend measuring voltage, may be latching voltage with one of peak detector circuit - converting it to digital and transmitting it. Using peak detector would give you time to process that data, while battery under test gets unloaded from ZIG and new one get loaded. You need to reset peak detector between two measurement.
    The road of life twists and turns and no two directions are ever the same. Yet our lessons come from the journey, not the destination. ~ Don Williams, Jr.



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    Re: Reading the voltage between battery terminals in an automated product line

    I had a look at the peak detector circuit, from what I found it was applied to AC circuits, the one in which the battery would be used is considered DC? No?

    You need to reset peak detector between two measurement.
    So after every measurement it would have to be reset?

    Thanks
    Al


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    Re: Reading the voltage between battery terminals in an automated product line

    Dear proudgrover47
    I built a battery charger circuit and it is working well but I want that How would battery be charged it show by 5 LEDs and show that if battery is charge 20% 1st LED blow, 40% 2nd LED blow...................5th LED blow means full charge.How it can possible?
    IMRAN



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    Re: Reading the voltage between battery terminals in an automated product line

    Leds are driven by current, so if your device is producing 5V, you need some sort of resistor to limit the current (work on the basis that the LED will drop 2V it's self). So 20 mA @ (5 - 2 V) = 150 ohms, try 220 ohms for 5V.
    Frank


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    Re: Reading the voltage between battery terminals in an automated product line

    How would battery be charged it show by 5 LEDs and show that if battery is charge 20% 1st LED blow, 40% 2nd LED blow...................5th LED blow means full charge.How it can possible?
    Can you an ADC's resolution as they suggested to me? so that when the battery is fully charged the resolution will actuate (light up) the 5 LEDs while say at 20% resolution it will light up one LED?

    Please put a current load on the battery under test, voltage will not tell you anything about the batteries internal impedance.
    I was loooking at ADCs and when applied I noticed that there is a resistor used in a voltage divider setup. Is the setup suggested the same?



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    Re: Reading the voltage between battery terminals in an automated product line

    I have UPS of APC (Company name) , 5 leds show the status of battery but i dont know which technique or circuit used for showing battery status.Do you know about it?
    I will 1st time try ADC and tell you after experiment.
    IMRAN



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