Battery safety rules at race meetings, body by body.

EFRA

General Rules, 2024 edition

EFRA's General Rule 5.3.12 (2024) says that, in the interest of safety, any battery pack carried on a model car must be able to be disconnected quickly in an emergency, and that direct soldering of battery packs is not acceptable. The same rule requires all racing batteries, car and radio equipment to be charged in a "Lipo sack" at all times, and defines a LiPo sack as a receptacle designed for charging LiPo and LiFe batteries and built so as to contain a fire. That definition is the wording of the rule; it is not a test result. Rule 5.2.2 requires a sand box and a fire extinguisher on the drivers' rostrum when the transmitter impound is there. EFRA's 2026 General Rules were not read and may differ.

Appendix 4, 2026: lithium batteries for electric classes

• Cells and case (rule 1.1). Approved cells are lithium based, LiPo or LiFe. Packs must have a hard protective case, ABS or similar, completely enclosing the cells and factory sealed so that opening it destroys it. A step or recess near the connectors is allowed, in the rule's words, to prevent any short circuit.
• No modification (2.1). Removing material from the case, or any modification that could be deemed to affect safety, is banned.
• Chargers (2.2 and 2.3). The rule requires a LiPo/LiFe-capable charger using the constant-current/constant-voltage profile, and says competitors who break this, or charge above the rule 2.7 voltages, will be penalised at the event.
• LiPo sack (2.4). Drive batteries must be in a LiPo sack at all times when charged or discharged, except during a race or on resistors supplied by the organiser, with a penalty at the event for anyone not doing so. The rule repeats the definition of a sack as built to contain a fire.
• No heating or cooling (2.5). Any added heating of a battery, and any cooling device or freeze spray, is banned.
• Voltage cap (2.7). Charged voltage is capped, for example at 8.40 V for a 2S LiPo and 16.80 V for a 4S LiPo, and the rule states that overcharging is a serious safety hazard and will not be tolerated.
• Current cap (2.9). Charge and discharge currents are capped as a matter of safety; a competitor caught breaking this during a control is asked to leave and disqualified from the whole event.
• Approval (3.3(a)). Each battery submitted for EFRA approval must carry safety test certification under sub-section 38.3 of the UN Manual of Tests and Criteria, tests T1 to T8.

Appendix 3, 2026: electric cars

EFRA's 2026 electric rules (Appendix 3, v4) repeat the LiPo-sack requirement (A 3.4) and require a fire extinguisher always to be in the pits to deal with a burning battery (A 9.1.4).

A disagreement inside EFRA's rules

The two EFRA documents describe the sack rule differently. General Rule 5.3.12 (2024) applies it to all racing batteries, car and radio equipment, whatever their material, whenever they are charged. Appendix 4 rule 2.4 (2026) applies it to LiPo and LiFe drive batteries whenever they are charged or discharged. The 2026 General Rules wording was not read, so which text EFRA now treats as governing is not known.

IFMAR

Electric Racing Batteries and Motors, March 2023

IFMAR's batteries and motors document (version March 2023) applies at its electric World Championships. It approves only lithium-based batteries in the same kind of sealed hard case as EFRA's, and requires UN 38.3 tests T1 to T8 for approval. Rule 3.11 requires LiPo and LiFe drive batteries to be charged in a closed LiPo sack at all times, on pain of disqualification from the event, using the same definition as EFRA. Rules 3.12 to 3.14 cap charging at 8.40 V for a 2S LiPo and 4.20 V for a 1S LiPo, call overcharging a safety hazard punishable by disqualification, and ban heating or cooling batteries, including freeze sprays. Rules 3.9 and 3.10 require a LiPo/LiFe-capable charger using the constant-current/constant-voltage profile and ban converted PC power supplies feeding chargers. IFMAR's electric off-road rules (2019, rule 4.1) add random lithium voltage checks at technical inspection.

1/8 e-buggy rules, April 2023

IFMAR's 1/8 electric off-road book (rule 2.3) caps charged voltage at 4.20 V per cell (16.80 V for 4S), checked before any run, requires batteries to be protected by the chassis or body and checks them for deformity, and requires drive batteries to be in a LiPo sack whenever charged or discharged, except in a race or on organiser resistors. Rule 3.7.j says the organiser should provide fire extinguishers and buckets of water because the event uses LiPo batteries. That is a rule about what the organiser provides, not guidance.

When a sack is required: EFRA and IFMAR differ

EFRA's Appendix 4 (2026) and IFMAR's e-buggy book (2023) require a sack whenever drive batteries are charged or discharged. IFMAR's March 2023 batteries and motors document (rule 3.11) speaks only of charging. Each applies to its own events.

ROAR

ROAR's current rule book could not be read for this site, so its present battery rules are not known here. Two older sources exist, and neither is confirmed as current:

• A 2011 reprint. LiveRC reprinted ROAR's battery rules on 26 May 2011. They required LiPo packs to have a hard protective case with a "ROAR Approved" label across the seam (8.3.2.2), a certificate showing the cells passed UN transport tests (8.3.2.1), and set the maximum charged voltage at 4.25 V per cell (8.50 V for 2S), with no allowance for overage (8.3.2.5.2).
• A 2015 trade report. LiveRC reported that at the 2015 ROAR Electric Off-Road Nationals batteries had to be charged in flame-resistant safety bags, deliberate heating of packs was banned, and a driver who reached pre-race technical inspection with an overcharged or overheated pack was disqualified.

A voltage disagreement. ROAR's 2011 text allowed 4.25 V per cell. IFMAR (March 2023) and EFRA (2026) cap LiPo cells at 4.20 V. Whether ROAR's current figure is still 4.25 V was not confirmed.

BRCA

The BRCA's handbook battery rules were not read. A search summary of one BRCA regional series page, not opened, says its rules follow the BRCA Handbook, that random cell-voltage checks can be made before each heat, and that LiPo batteries must be charged in a protective container; that is unconfirmed. The BRCA's Electric Board also lists a 2017 document called "Lithium Safety Explanations"; its listing distinguishes hard-case from soft-case batteries, but the document itself was not read.

The rules side by side

The technical battery rules for each class, including the receiver-pack and length disagreements between EFRA and IFMAR, are on battery rules by body. Airline carriage rules are on travelling with batteries.