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High-Current, High-Voltage Battery Capacity Meter, Pt.2

Last month we presented the full description, operation and construction details of our new Battery Capacity Meter. This month we guide you through the once-only setup and calibration. We also explain in detail how to use it!

By Mauro Grassi

Assuming you have completed the Battery Capacity Meter and installed it in its case, now it’s time to calibrate it and set it up, ready for use.

We’ve also shown the various LCD readouts and what they mean – sorry the type is so tiny but we had to get a lot of information in!

After use, most of these screen messages and sub-menus will become very much self-explanatory and common sense. And you can always refer back to this article if you need to!

One Time Calibration

To calibrate the meter, you will need to follow these steps:

(1) Measure the voltage between pin 2 (GND) and pin 1 (+5V Rail) of CON4 using a DMM. Note this voltage and enter it in the CALIBRATION>Set +5V Rail SubMenu;

(2)  Measure the voltage between pin 2 (GND) and pin 5 (Low Battery Voltage) of CON4 using a DMM. Note this voltage and enter it in the CALIBRATION>Calibrate Lo. Divider SubMenu;

Click for larger image
This shows all the available readings. Each is chosen by a single digit press on the alphanumeric keypad. For example, if you wish to display the battery voltage, type ‘3’. Or if you wish to see the battery capacity in Watt Hours and the load in Watts, press ‘*’. Notice that from here, you may press ‘#’ to enter the extensive menu system. The remaining panels illustrate in detail the various submenus.

(3) Measure the voltage between pin 2 (GND) and pin 6 (High Battery Voltage) of CON4 using a DMM. Note this voltage and enter it in the CALIBRATION>Calibrate Hi. Divider SubMenu;

(4) Enter the value of your shunt resistance (in mΩ) in the CALIBRATION>Shunt Resistance SubMenu;

(5) Enter the CALIBRATION> Calibrate Current SubMenu. Apply a small load of say a few amps to the LOAD terminal through a DMM. Note the current registered on the DMM and enter it;

(6) Enter the value of the gain of the load amplifier (usually 60.0 for the MAX4080SASA) in the CALIBRATION>Load Amp. Gain SubMenu;

(7) Enter the value of the gain of the charge amplifier (usually 60.0 for the MAX4080SASA) in the CALIBRATION>Charge Amp. Gain SubMenu;

(8) Enter the value of your sense resistance (usually 10Ω) in the CALIBRATION>Sense Resistance SubMenu;

(9) Enter the CALIBRATION>Detect Sense Resistance SubMenu. Connect the DMM in series between the GND terminal of the meter and the negative battery terminal. Note the instantaneous circuit current and enter it (in mA);

That completes the calibration.

One-time user setup
After the calibration is performed, you should run through the following checklist to set up your preferences:

(1) Go to the BATTERY SubMenu;

(2) Enter the full capacity of your battery in the Battery Capacity SubMenu;

(3) Enter Peukert’s constant in the Peukert’s Constant SubMenu if you are using a Lead Acid battery;

(4) Enter the cell chemistry in the Cell Chemistry SubMenu;

(5) Enter the charging efficiency in the Charging Efficiency SubMenu;

(6) Enter the cycle threshold in the Cycle Threshold SubMenu;

(7) Exit the BATTERY SubMenu;

(8) Go to the DISPLAY SubMenu and set up the display backlight preferences like brightness and time out period;

(9) Go to the DETECTION SubMenu;

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