Question about battery

The rules 3.14 states : Every robot should be equipped with some sort of battery power, with a maximum of 15 volts.

Is this max non-negotiable or is there a way to perhaps instead use a 24V battery? The robot in question needs 24V which goes against the rules.

Thank you for your inquiry. This is one of the rules to ensure the safety of the robots and people around them. Why do you need to use 24V battery in your performance? Maybe there are many ways around to make it work for your purpose?

I’m wondering about the same. Higher voltage motors often provides better torque with lower current, and the team may wish to build their robot using repurposed components (eg. cordless drills) which often run at voltages above 12V.

24V is well below the NFPA 70E threshold of 50V for hazardous touch voltages. Granted there can be other hazards even at 24V (eg. battery fire, arc flash), but these hazards exist for batteries below 15V as well (…the famous Samsung Galaxy Note 7 battery is only 3.85V).

Hello everyone,

we have internally discussed the voltage regulations and also took a look at the other leagues restrictions. We are open to modify the limits in the rules for the 2025 season and will combine that with some other safety measures like the mandatory use of fuses.

Unfortunately we can not make such changes at this moment, as the regional selection events have already took place in some regions and we want to provide equal conditions for their each of you.

Feel free to comment with any suggestions regarding the future regulations regarding the voltage and type of battery that may be used as well as mandatory safety measures like fuses, emergency stop switches, …?

I would suggest…

  1. Mandatory fuses to be installed at the nearest possible point to the battery. This will minimize fire hazard. Fuse rating should be left up to the team to decide as there is no one-size-fit all solution for this (ie. 10A may be too little for some robots, but far too much for others).

  2. Sealed lead acid batteries should be allowed. While there are some risks of these batteries rupturing when abused, I would opine that the hazard is lower than that of a Lipo battery fire. One concern that I would have for lead acid batteries, is that their terminals are usually exposed, making it much easier for a short to occur, but that is also a possible (…but less common) risk for Lipo batteries.

  3. Emergency stop would be a reasonable requirement, but I would advice careful wording of the rules…

a) Requiring a single emergency stop to fully power down the robot may be difficult and unnecessary. Some robots may have multiple sub-systems with their own power supply. For example, when driving 12V motors as well as RC Servo at 7.2V, one could step down the voltage, but with the RC servos drawing 10s of Amps at peak, a separate battery supply would be much simpler and cheaper than sourcing for an suitable step-down regulator. Perhaps it could be worded as one emergency stop per power source.

b) Not everything will need an emergency stop. A big Lipo battery powering an 500W motor would benefit from an emergency stop, but an Arduino controlling only sensors and LEDs would not. I would suggest that the emergency stop be applicable only for moving parts.

  1. Voltage limit should be raised to at least 24V to support common motors. Possibly even higher for other less common motors (eg. I’ve seen some teams use hoverboard motors in their robot; that’s a 36V motor).

For your considerations.

May I share a Japanese case study on the handling of rechargeable batteries?

The RoboCupJunior Japanese Domestic Committee asks each team to submit detailed information about the rechargeable batteries they will use, including schematics, in advance. Please see the following two documents:

These additional procedures regarding batteries do not intend to regulate the students’ activities. As long as students can demonstrate that they understand the products they are using and are using them safely, teams will be allowed to use those batteries. At the same time, we adults involved in competition running learn a lot from the various new products used by teams and how students use them. Since the soccer league mainly led the discussion, the current documents are more soccer-oriented. However, the OnStage League also asked teams using Li-Po, mobile batteries, lead-acid batteries, etc., to submit these documents at the recently held Japan Open. I think it worked well.

Apart from the above, we are considering restricting the rechargeable batteries’ specifications to “those that can be carried on board an aircraft”. As you know, there are restrictions on the type and capacity of rechargeable batteries when boarding flights. The primary purpose of this regulation is to ensure equality for participants from different regions who come to the venue using various transportation methods.

FYI :slightly_smiling_face: