This guide will give you some insight into working with Lithium Polymer (LiPo) batteries with the ArbotiX Robocontroller and InterbotiX Robot Kits. This guide is not intended as a comprehensive Li-Po Battery /LiPo Charger guide. Make sure to read any instructions or warnings included with your LiPo Charger and Batteries.
- Do not charge or use batteries if the battery ...
- is punctured or damaged
- is bloated, expanded, swelling or otherwise deformed
- has any cell with a voltage of 3.3v. This means less than 9.9v for a 3-cell/11.1v battery.
- Do not charge batteries unattended. Monitor batteries during charging for popping, hissing, smoke, sparks or fire. Also monitor the battery for any swelling or other deformities. Disconnect the battery from your charger immediately.
- Do not charge batteries near flammable material. Charge batteries in a fireproof container. Do not charge batteries while they are in your robot.
LiPo Battery AnatomyYour LiPo Battery will have two connectors on it - a Balance Connector and a T-Connector (sometimes called a "Dean's Connector").
|Balance Connector||Charging and monitoring your battery|
|T-Connector||Charging and discharging your battery|
LiPo Batteries are comprised of 3.7v cells. I.E. a 11.1v battery has three-3.7v cells. The balance connector gives you individual access to each of these cells. This will allow you to individually monitor and charge cells. This is called 'Balance Charging' and will increase the lifespan of your battery.
Note:The balance charger is not designed for discharging, so never plug it directly into a robot that you want to power.
T-ConnectorThe T-Connector gives you access to the full voltage across all of the cells of the battery. The T-Connector is primarily used to supply power to your robot.
Testing and Monitoring Your Battery
We recommend that you use your LiPo battery with a Battery Voltage Tester/Monitor. This device is capable of monitoring each cell in your battery and sounding an alarm when the battery gets too low. This is essential for the care of your battery - if you let your battery fall to low in voltage, the battery will become permanently damaged and unusable.
To attach your battery to the Battery Tester/Monitor, first find the ground wire on the balance connector. This wire will be the one farthest away from the red wire. Match the ground wire up to the minus symbol on the back of the Tester/Monitor. The red wire should match up to the 3s pin.
Once your battery is connected, the Tester/Monitor will make a noise. It will then cycle through various measurements
- ALL:The voltage across the entire battery.~11.1 nominal voltage, this may vary when fully charged or after discharge.
- No.1:The voltage across the first cell of the battery. ~3.7 nominal voltage, this may vary when fully charged or after discharge.
- No.2:The voltage across the second cell of the battery. ~3.7 nominal voltage, this may vary when fully charged or after discharge.
- No.3:The voltage across the third cell of the battery. ~3.7 nominal voltage, this may vary when fully charged or after discharge.
We recommend that you attach your Battery Tester/Monitor whenever you are running your robot. When you are done running your robot, remove the Battery Tester/Monitor. Do not store the battery with the Battery Tester/Monitor attached, as the tester will slowly drain the battery
You can push the button on the battery monitor to change the voltage that the alarm will sound (or even turn it off). You can change the monitor to values between 2.7 and 3.8V. We recommend the default setting of 3.3v.
Connecting a Battery to Your Robot
LiPo batteries with a T-Connector/ Dean's connector can easily be plugged into an ArbotiX Robocontroller using a Battery Wiring Harness. This harness converts the T-connector into a DC barrel jack that plugs directly into the ArboitX Robocontroller. The harness also has a switch to easily shut power off to the ArbotiX Robocontroller. Every Hexapod and Quadruped kit comes with one of these harnesses.
Charging your battery
- Connect your Battery's T-Connector to the T-connector-to-Banana-Plug Cable. Plug the red and black banana plugs into the LiPo Charger.
- Connect the Balance Connector to the 3 Cell port in the LiPo Charger
- Plug your 12v 5A power supply into the Balance Charger using a 2.1/5.5mm Jack to 2.5/5.5mm Plug Adapter
- Press the Batt. Type button until you see
PROGRAM SELECT LiPo BattThen press the Enter button.
- Press the Inc. button until the first line of the screen changes to
LiPo BalanceThen press the Enter button.
- The Charge Current will begin to flash. This setting will depend on your specific battery. For example, the 11.1v 2200mAh LiPo Battery that comes with InterbotiX Crawler kits has a Recommended Charge Current of 2.2A. Be sure that you do not exceed the recommended Charge Current for your particular battery.
Use the Dec. and Inc. buttons to change the flashing current value. Once you have set the current to the desired value, press 'Enter'
- The Charge Voltage will begin to flash. Use the Dec. and Inc. buttons to change the flashing voltage value. Once you have set the voltage to 11.1 (to match your battery), press 'Enter'
- Now all numbers should stop flashing. Press and hold the Start button. The screen will flash a message
BATTERY CHECK WAIT...Then the screen will change to
R: 3SER S: 3SER CONFIRM(ENTER)Press the Start button one more time to begin charging your battery.
- Your battery will take 1-2 hours to charge.When the battery is charged your charger will begin to make a noise. Disconnect the battery and unplug the charger from power.
Note: Do not leave your charger unattended while it charges a battery. Monitor the battery for extreme changes in temperature or shape. If the battery begins to smoke or make an 'popping' noise, disconnect the battery immediately.
You can also charge your battery using the 'LiPo Charge' mode. For this mode you will only need to connect the T-Connector, and the charging will complete faster than with Balance Charge mode. However this mode will not monitor the individual batter cells and may reduce the lifespan of your battery.