# Which chip used to optimize measuring many batteries.ject

#### hples

Aug 13, 2016
12
My project is to measure 12 V voltage of a number of batteries on the same circuit and then monitor on PC.
I'm not going to design one circuit for one battery but one circuit all batteries (36 batteries expected).
This circuit must be optimized to reduce number of electronic components. I, at the beginning, intended using some MUX to multiplex 12v signal from batteries before sending to MCU. However there is no MUX with 12 v (exactly 0 V-16 V) input.
I'm finding another component to replace MUX, does anybody help me?

#### duke37

Jan 9, 2011
5,364
The 4066 has four switches which could be utilised.
If the batteries are in series, the voltage could be very high. If the batteries are in parallel, there will be only one voltage to measure.

#### Arouse1973

Dec 18, 2013
5,177
Are the batteries in series or parallel?

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
Or are the batteries even connected in any way? If they are, do they share a common -ve (for example)

If the answer to all this is "it can vary" then you may have to use relays to switch birth dudes of the batteries and logic to ensure only a single relay is powered. Additionally you will need an isolated power supply.

#### hples

Aug 13, 2016
12
The 4066 has four switches which could be utilised.
If the batteries are in series, the voltage could be very high. If the batteries are in parallel, there will be only one voltage to measure.
Thanks duke37, my batteries are in series so that this measurement will be affected by floating voltage. That's why i'm finding a multiplexer with input 0-16V.

#### hples

Aug 13, 2016
12
Are the batteries in series or parallel?
Are the batteries in series or parallel?
Thanks Adam, my batteries are in series. You know batteries are connected to UPS in series.

#### hples

Aug 13, 2016
12
Or are the batteries even connected in any way? If they are, do they share a common -ve (for example)

If the answer to all this is "it can vary" then you may have to use relays to switch birth dudes of the batteries and logic to ensure only a single relay is powered. Additionally you will need an isolated power supply.
Thanks, yes I'm going to use relay for each battery, however 36 units need 36 relays it perhaps very bulky That's why I find MUX for more simple.
Yes, Isolating power supply is needed.

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
If you have ten 12V batteries in series you would need a 150V mux and you would require a common ground with the battery pack. But you'd have problems with that.

You could use dc optoisolated mosfets (dc ssr) but you would also need a large number of these and they would need to be rated for the battery pack voltage.

Last edited:

#### hples

Aug 13, 2016
12
If you have ten 12V batteries in series you would need a 150V mux and you would require a common ground with the battery pack. But you'd have problems with that.

You could use dc optoisolated mosfets (dc ssr) but you would also need a large number of these and they would need to be rated for the battery pack voltage.
Steve, If I measure the whole battery string it will be 150V, in this case I measure individual battery so that the output must be in battery voltage range (0-16V). I need MUX or similar solution to multiplex 36 inpust into one or more output.

#### Arouse1973

Dec 18, 2013
5,177
You can do this with a small 1:1 transformer across each battery. You will need a diode to prevent the shorting of the battery and a resistor on the primary so you can measure the voltage across it. Pulse the primary winding with a short pulse and measure the voltage across the primary resistance. You will need to calibrate it because of the secondary diode and then you could mux them to an AD port or something like that.

#### Arouse1973

Dec 18, 2013
5,177
Here is part of the circuit.

Thanks

#### hples

Aug 13, 2016
12
Here is part of the circuit.
View attachment 28476
Thanks
Adam, the left site of your circuit is still MUX, but the voltage is divided in order to be same input voltage of MUX, right?
Thanks.

#### Arouse1973

Dec 18, 2013
5,177
You can MUX in the output from the primary resistor yes. So you drive which ever transformer you want and then read back the voltage from the resistor you want using your MUX to switch it.

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,505
You may want to pass the resulting waveform into a peak hold circuit.

The voltage read here will not be the battery voltage. You will need to determine a calibration curve to convert the peak voltage to a battery voltage

#### Sunnysky

Jul 15, 2016
499
My project is to measure 12 V voltage of a number of batteries on the same circuit and then monitor on PC.
I'm not going to design one circuit for one battery but one circuit all batteries (36 batteries expected).
This circuit must be optimized to reduce number of electronic components. I, at the beginning, intended using some MUX to multiplex 12v signal from batteries before sending to MCU. However there is no MUX with 12 v (exactly 0 V-16 V) input.
I'm finding another component to replace MUX, does anybody help me?
Why is component count so important if they are inexpensive parts?

If I understand you, 32x14.2 =512V is your battery voltage but you need Battery voltage for each cell, yet you have not mentioned load balancing.

This design detail "spec" is insufficient, or at least inconsistent with good practice.
You could define resolution, accuracy, range, for V of each cell and method of readings.

The overall purpose would give your query more focus, with a budget, features and purpose.

Last edited:

Aug 24, 2009
823
4067 ?

Jul 15, 2016
499

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