Asked — Edited


We're holding a robotics camp at our school. We left the battery charging overnight and the charger lights were off when we arrived this morning. JD still tells us that the battery is low. What could have happened? How long does it take for a battery to charge? Is it supposed to get extremely hot?


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United Kingdom

It should take around one and a half hours to charge, roughly.

Did you connect the battery to the charger correctly? Was the robot turned off while charging? Were both lights on when you connected it originally?

One light on the charger shows it's receiving power. If this is not on it will not charge the battery as it will not be receiving power from the wall outlet. I would say that either the wall outlet was turned off or the charger was unplugged.

Do any lights on the charger light up when plugged in to the wall outlet now?


We think so. We're letting him recharge now. We've been having problems as we have to use a dongle to have the wireless connection and it doesn't always connect. I don't have a good understanding of the servos either. Our regional rep just pointed me to the website.

United Kingdom

Wireless & servos are unrelated to charging.

The main thing to check is the charger lights up when you plug it in the wall outlet and both LEDs light up when you connect it to the robot.

If the robot is saying the battery is low turn it off and leave it off as undervolting* a battery will cause permanent damage to the battery and you will be unable to charge it at all.

  • Undervolting is to discharge the battery below the threshold which can vary from battery to battery but generally if a cell is below 3v it may stop accepting a charge.

You can check for under voltage by using a multimeter on two of the three pins on the balance plug. Put one lead on the far outside pin and one on the middle pin to test one cell, then move the leads to test between the middle pin and the other outside pin to test the other cell.

Or buy one of these and plug the balance port (on the robot) in to it.

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