Race within the rules
This page explains what governing bodies, regulators, standards bodies and researchers publish. It is not a substitute for your class's rule book, a track's safety rules, the race director or the makers' instructions.
An aid, not a ruling
This tool compares figures you type in with the battery limits in the EFRA Handbook 2026 (Appendices 3 and 4) or IFMAR's battery rules (March 2023, and the April 2023 e-buggy rules for 1/8). It does not check whether a pack is on a body's approved list, which decides whether it may race, and it does not cover ROAR, national bodies or a club's own rules. Officials check batteries at the event. Nothing here is about charging: see battery rules at events.
Check a battery
The limits the tool uses
EFRA's figures are from the EFRA Handbook 2026: Appendix 4 for cell ratings (1.4), charged voltages (2.7) and case sizes (1.2), and Appendix 3 for which pack each class uses (A 3.1 to 3.3). IFMAR's are from its World Championship battery and motor rules dated March 2023 and, for 1/8 electric, its e-buggy rules made in April 2023.
| Pack | Nominal (LiPo / LiFe) | Charged (LiPo / LiFe) | Case, at most |
|---|---|---|---|
| 1S, EFRA and IFMAR (1/12) | 3.8 V / 3.3 V | 4.20 V / 3.70 V | 93.0 x 47.0 x 18.5 mm |
| 2S, EFRA (1/10 touring, FWD, F1, off-road) and IFMAR (1/10 off-road, touring, F1) | 7.6 V / 6.6 V | 8.40 V / 7.40 V | 139.0 x 47.0 x 25.1 mm (EFRA writes 25.10) |
| 4S, EFRA Appendix 4 | 15.2 V / 13.2 V | 16.80 V / 14.80 V | 139.0 x 47.0 x 48.2 mm |
| 4S, IFMAR e-buggy (1/8 electric off-road) | at most 15.2 V | 16.80 V (4.20 V per cell) | not given in the rules as read |
What the tool does not check
- Whether a pack is on the approved list. Both bodies allow only listed packs, and that list decides.
- ROAR's rules. The only ROAR battery text read is a 2011 reprint, which allowed 4.25 V per cell; whether that is still ROAR's figure was not confirmed. See battery rules by body.
- Which EFRA classes use 4S packs. Appendix 4 sets 4S sizes and voltages, but EFRA's 1/8 electric class rule was not read.
- Receiver packs, which the bodies treat differently in 1/10 off-road, and every rule about charging, heating or cooling batteries at an event.
- National bodies' and clubs' own rules.
Sources
- EFRA Handbook 2026, Appendix 4 (batteries and motors)
- EFRA Handbook 2026, Appendix 3 (electric cars), v4
- IFMAR World Championship Electric Batteries and Motors (March 2023)
- IFMAR 1/8th E-buggy Off-Road Racing and Technical Rules (April 2023)
- ROAR battery rules as reprinted by LiveRC (26 May 2011; historical)