Question
Asked March 10 2013

Community Question

As also posted in my Hearoid showcase topic, but useful for anyone running LiPo batteries (could be adapted easily for 3S and 4S without too much of a problem).

Parts needed:
1 x Zener Diode 5.1v 500mA (Farnell ref 1861447)
3 x 100k ohm Resistors (Farnell ref 9339078)
1 x Small Piece of Strip Board (12 strips x 7 rows) - Maplin FL17T
3 x Pin Header (1x3) or 1 x Pin Header (1x3) and 1 x Pin Header (1x6) eBay Search
1 x servo Extensions (male to male) - made from 2 normal ones cut & soldered.
Solder
Soldering Iron
Cutters


The Schematic:
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Method:
1. Solder R1 - 100k resistor from Row 2 Column 3 to Row 2 Column 11
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2. Solder R2 - 100k resistor from Row 3 Column 5 to Row 3 Column 11
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3. Solder R2 - 100k resistor from Row 4 Column 7 to Row 4 Column 11
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4. Solder D1 - Zener Diode from Row 5 Column 5 to Row 5 Column 11 (Band to the right)
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5. Solder the pin headers on Row 1 Columns 1, 2, 3, 5, 6, 7, 8, 9 & 10
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6. Solder some black off cuts of wire from Row 6 Column 1 to Row 6 Column 5 and from Row 7 Column 5 to Row 6 Column 8
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7. Solder an off cut of red wire from Row 7 Column 2 to Row 7 Column 10
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8. You're all done. Plug the balance port connector in to the 3 pin header on Row 1 Columns 1 to 3 (Ground to the left) and plug in some servo extensions (male to male) or 3 pin JST to servo on the two other headers (Ground on left on both), connect the other ends to ADC0 and ADC1 (or any other two ports if those are taken but you will need to adjust the script below if you do).

Now, to use the information in EZ-Builder...

The EZ Script

Code:


# Read voltage level of 2S LiPo battery and report to software.
# Set variables
# Change $vundervoltage to the under voltage of your specific battery (leave at 3v if unsure)
# Change $vcritical to your lowest voltage you wish for the battery to get before human intervention
# Change $vmin to low level alert value
# Change $vmax to battery full charge
# Change $multiplyer if using voltage divider
# Factor is 5/255 for adc value conversion to volts
$vundervoltage = 3
$vcritical = 3.5
$vmin = 3.7
$vmax = 4.5
$multiplier = 2
$factor = 0.019607843

:ReadCells
# Get ADC values
$vc1 = GetADC(ADC0)
$vc2 = GetADC(ADC1)

# Convert values to voltage
$cell2 = $vc1 * $factor
$cell1 = $vc2 * $factor * $multiplier
$cell1 = $cell1 - $cell2
$batteryv = $cell1 + $cell2

# Check for errors on circuit
IF ($cell1 > $vmax or $cell2 > $vmax)
Print("Battery Monitor Error")
Print("Check Monitor Circuits")

# Check for errors on battery connection
ELSEIF ($cell1 <= 0 or $cell2 <= 0)
Print ("Battery Connection Error")
Print("Check Battery Connection")

# Check for under voltage
ELSEIF ($cell1 <= $vundervoltage or $cell2 <= $undervoltage)
Print ("Battery Under Voltage")
Print("Check Or Replace Battery")

# Check if at critical levels
# Cell 1
ELSEIF ($cell1 <= $vcritical)
# Do sometihing if critical
Print("Cell 1 Critical")
# Shut down all power, switch to back up battery alarm?

# Cell 2
ELSEIF ($cell2 <= $vcritical)
# Do sometihing if critical
Print("Cell 2 Critical")
# Shut down all power, switch to back up battery alarm?

# Check if below recommended levels
# Cell 1
ELSEIF ($cell1 < $vmin)
# Do sometihing if voltage low
Print("Cell 1 Low")

# Cell 2
ELSEIF ($cell2 < $vmin)
# Do sometihing if voltage low
Print("Cell 2 Low")

ELSE
# Output voltages
Print("C1 Round($cell1,2)V")
Print("C2 Round($cell2,2)V")
Print("To Round($batteryv,2)V")
ENDIF
# Wait 5 seconds
Sleep(5000)

# Go back to the start
Goto(ReadCells)


Note: The;) should be just a normal closed bracket ) but the forums tend to think otherwise.

EZ-Cloud Download


Update: Refer to page #2 post #18 for updated code taking in to account the updated syntax
July 8 2013
I'm sure that eventually all tutorials etc. will get listed as appropriate. It's in the tutorial index I started, which is marked as a tutorial so it's halfway there:)
July 9 2013
I had a few minutes spare so adjusted the script to suit a 12v Lead Acid battery (or any Lead Acid battery really)

Code:


# Read voltage level of a single battery pack and report to software.
# Adapted from LiPo monitor circuit.
# Assumed monitor circuit connected to ADC0
# Set variables
# Default values set for 12v Lead Acid. For 6v divide by 2
# Change $vundervoltage to the under voltage of your specific battery if required
# Change $vcritical to your lowest voltage you wish for the battery to get before human intervention
# Change $vmin to low level alert value
# Change $vmax to battery full charge
# Change $multiplyer if using voltage divider
# Factor is 5/255 for adc value conversion to volts
$vundervoltage = 10.50
$vcritical = 11.31
$vmin = 11.58
$vmax = 12.70
$multiplier = 4
$factor = 0.019607843

:ReadCells
# Get ADC values
$vc1 = GetADC(ADC0)

# Convert values to voltage to 2 decimal places
$batterylevel = $vc1 * $factor
$batterylevel = $batterylevel * $multiplier
$batterylevel = Round($batterylevel,2)

# Check for errors on circuit
IF ($batterylevel > $vmax)
Print("Battery Monitor Error")
Print("Check Monitor Circuits")

# Check for errors on battery connection
ELSEIF ($batterylevel <= 0)
Print ("Battery Connection Error")
Print("Check Battery Connection")

# Check for under voltage
ELSEIF ($batterylevel <= $vundervoltage)
Print ("Battery Under Voltage")
Print("Check Or Replace Battery")

# Check if at critical levels
ELSEIF ($batterylevel <= $vcritical)
# Do sometihing if critical
Print("Battery Critical")
# Shut down all power, switch to back up battery alarm?

# Check if below recommended levels
ELSEIF ($batterylevel < $vmin)
# Do something if voltage low
Print("Battery Level Low")

ELSE
# Output voltages
Print("$batterylevel V")
# Output to LCD display here (if required)
ENDIF
# Wait 5 seconds
Sleep(5000)

# Go back to the start
Goto(ReadCells)


This assumes a 1/4 voltage divider has been used to drop the 12v down to 3v which is suitable for the ADC port (5v max). If you use a 6V battery you can use a 1/2 voltage divider and adjust the values to suit.

Default voltage levels are based on 12v Lead Acid. Divide these by 2 for 6v Lead Acid. Multiply by 2 for 24v Lead Acid. Etc.

Hopefully it all makes enough sense to be usable and adaptable for anyone and any battery.

I plan to add in automatic calculations for different voltage levels and output to LCD display. I can also adjust it for any battery type, please request your specific battery type should it not be covered.
July 22 2013
Updated code to suit 2013.07.22 release of EZ-Builder with the syntax change.
Currently untested - will check and adjust (if required) later


2S LiPo Version

Code:


# Read voltage level of 2S LiPo battery and report to software.
# Set variables
# Change $vundervoltage to the under voltage of your specific battery (leave at 3v if unsure)
# Change $vcritical to your lowest voltage you wish for the battery to get before human intervention
# Change $vmin to low level alert value
# Change $vmax to battery full charge
# Change $multiplyer if using voltage divider
# Factor is 5/255 for adc value conversion to volts
$vundervoltage = 3
$vcritical = 3.5
$vmin = 3.7
$vmax = 4.5
$multiplier = 2
$factor = 0.019607843

:ReadCells
# Get ADC values
$vc1 = GetADC(ADC0)
$vc2 = GetADC(ADC1)

# Convert values to voltage
$cell2 = $vc1 * $factor
$cell1 = $vc2 * $factor * $multiplier
$cell1 = $cell1 - $cell2
$batteryv = $cell1 + $cell2

# Check for errors on circuit
IF ($cell1 > $vmax or $cell2 > $vmax)
Print("Battery Monitor Error")
Print("Check Monitor Circuits")

# Check for errors on battery connection
ELSEIF ($cell1 <= 0 or $cell2 <= 0)
Print ("Battery Connection Error")
Print("Check Battery Connection")

# Check for under voltage
ELSEIF ($cell1 <= $vundervoltage or $cell2 <= $vundervoltage)
Print ("Battery Under Voltage")
Print("Check Or Replace Battery")

# Check if at critical levels
# Cell 1
ELSEIF ($cell1 <= $vcritical)
# Do sometihing if critical
Print("Cell 1 Critical")
# Shut down all power, switch to back up battery alarm?

# Cell 2
ELSEIF ($cell2 <= $vcritical)
# Do sometihing if critical
Print("Cell 2 Critical")
# Shut down all power, switch to back up battery alarm?

# Check if below recommended levels
# Cell 1
ELSEIF ($cell1 < $vmin)
# Do sometihing if voltage low
Print("Cell 1 Low")

# Cell 2
ELSEIF ($cell2 < $vmin)
# Do sometihing if voltage low
Print("Cell 2 Low")

ELSE
# Output voltages
$cell1round = Round($cell1,2)
$cell2round = Round($cell2,2)
$totalround = Round($batteryv,2)
Print("C1 " + $cell1round + "V")
Print("C2 " + $cell2round + "V")
Print("To " + $totalround + "V")
ENDIF
# Wait 5 seconds
Sleep(5000)

# Go back to the start
Goto(ReadCells)



SLA Version

Code:


# Read voltage level of a single battery pack and report to software.
# Adapted from LiPo monitor circuit.
# Assumed monitor circuit connected to ADC0
# Set variables
# Default values set for 12v Lead Acid. For 6v divide by 2
# Change $vundervoltage to the under voltage of your specific battery if required
# Change $vcritical to your lowest voltage you wish for the battery to get before human intervention
# Change $vmin to low level alert value
# Change $vmax to battery full charge
# Change $multiplyer if using voltage divider
# Factor is 5/255 for adc value conversion to volts
$vundervoltage = 10.50
$vcritical = 11.31
$vmin = 11.58
$vmax = 12.70
$multiplier = 4
$factor = 0.019607843

:ReadCells
# Get ADC values
$vc1 = GetADC(ADC0)

# Convert values to voltage to 2 decimal places
$batterylevel = $vc1 * $factor
$batterylevel = $batterylevel * $multiplier
$batterylevel = Round($batterylevel,2)

# Check for errors on circuit
IF ($batterylevel > $vmax)
Print("Battery Monitor Error")
Print("Check Monitor Circuits")

# Check for errors on battery connection
ELSEIF ($batterylevel <= 0)
Print ("Battery Connection Error")
Print ("Check Battery Connection")

# Check for under voltage
ELSEIF ($batterylevel <= $vundervoltage)
Print ("Battery Under Voltage")
Print("Check Or Replace Battery")

# Check if at critical levels
ELSEIF ($batterylevel <= $vcritical)
# Do sometihing if critical
Print("Battery Critical")
# Shut down all power, switch to back up battery alarm?

# Check if below recommended levels
ELSEIF ($batterylevel < $vmin)
# Do something if voltage low
Print("Battery Level Low")

ELSE
# Output voltages
Print($batterylevel + "V")
# Output to LCD display here (if required)
ENDIF
# Wait 5 seconds
Sleep(5000)

# Go back to the start
Goto(ReadCells)


If anyone tries any of these please report any errors and I shall correct to suit.
July 22 2013
Thanks Rich for the update on this!

Can't reply if it works or not as I haven't built the circuit yet but it is on my to-do list.
July 22 2013
Updated to fix the errors that remained.

Also now on the cloud, both scripts in one project. Download Here