Battery rules by body: what EFRA, IFMAR and ROAR each require.

EFRA and IFMAR agree on most battery rules: lithium only, factory-sealed hard cases, 4.20 V per cell, and UN 38.3 certificates for approval. They differ on receiver packs and on when a LiPo sack is required, and ROAR's only text read is from 2011. Each body's rules are given here separately, with the document and section. They are event rules, not charging instructions.

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.

A battery fire is an emergency

A burning or smoking lithium battery needs the emergency services. The rules below say what each body requires at its events; they are not charging, storage or firefighting instructions, and no rule's requirement is presented here as preventing a fire.

EFRA and IFMAR, side by side

EFRA's rules come from its 2026 Handbook, Appendix 4 (with class limits in Appendix 3); IFMAR's from its "Electric Racing Batteries and Motors" document, version March 2023, which governs its 1/12, 1/10 touring car, FWD, F1 and 1/10 off-road World Championships. Each applies only at that body's events.

Point	EFRA Handbook 2026	IFMAR, March 2023
Chemistry	Lithium based, LiPo or LiFe; lithium only since 2009 (App. 4, 1 and 3.1)	Lithium based only (1)
Cell rating	At most 3.8 V nominal LiPo, 3.3 V LiFe; 3.8 V cells since 1 April 2017 (1.4), while Appendix 3, A 3.1 gives 1 March 2017 for 3.8 V 1/12 batteries	At most 3.8 V nominal LiPo, 3.3 V LiFe (2.4 and 2.5)
Case	Hard, ABS or similar, completely enclosing the cells, factory sealed so opening destroys it, cuboid (1.1); no modification (2.1)	The same hard-case requirement (2.1 to 2.3)
Largest case, including plugs	4S 139.0 x 47.0 x 48.2 mm; 2S 139.0 x 47.0 x 25.10 mm; 1S 93.0 x 47.0 x 18.5 mm (1.2)	2S 139.0 x 47.0 x 25.1 mm; 1S 93.0 x 47.0 x 18.5 mm, no 1S saddle packs (2.1 to 2.3)
Weight	Within plus or minus 4 percent of the maker's stated weight (1.3)	Within 4 percent of the maker's figure (2.6 to 2.8)
Connections	Metal connections well below the case surface, to prevent a short circuit on a conductive surface (1.5)	Connection tubes below the case surface, for the same reason (2.6 to 2.8)
Maximum charged voltage	4.20 V per cell: 4.20 V 1S, 8.40 V 2S, 16.80 V 4S LiPo (3.70, 7.40, 14.80 V LiFe); EFRA calls overcharging a serious safety hazard (2.7)	4.20 V per cell: 4.20 V 1S, 8.40 V 2S LiPo (3.70, 7.40 V LiFe); IFMAR calls overcharging a safety hazard punishable by disqualification (2.5, 3.12 to 3.14)
Heating or cooling	Not allowed, including freeze sprays (2.5)	Banned, including freeze sprays (3.12 to 3.14)
During a race, and linked packs	Batteries cannot be charged or changed during a race (2.8); linked batteries must be the same brand and part number (2.6)	Cells may not be charged or changed (3.1 to 3.7)
Inspection	Only batteries shown on the official EFRA website are legal at EFRA-sanctioned events (2)	Batteries are checked and marked at technical inspection; unmarked cells may not be used (3.1 to 3.7). The 2019 electric off-road rules add random voltage checks (4.1)
Approval test	UN Manual of Tests and Criteria (Rev.8, or Rev.7/Amend.1), Part III, 38.3, tests T1 to T8 (3.3(a))	UN Manual (Rev.7 or later), Part III, 38.3, tests T1 to T8 (1)
Air travel	EFRA approves only batteries within passenger airlines' maximum energy capacities, because its events are international (1.7)	No such rule recorded in this site's research

Charging rules, named only

Both bodies set event rules on charging, which this site names without describing any procedure. EFRA (Appendix 4, 2.2, 2.3 and 2.9) requires LiPo/LiFe-capable chargers using the CC/CV profile and caps charge and discharge currents, with disqualification from the whole event for breaking the current cap. IFMAR (3.9 and 3.10) requires LiPo/LiFe-capable CC/CV chargers, bans converted PC power supplies feeding chargers, and disqualifies competitors who break this. EFRA's Appendix 3 (A 9.1.4) also requires a fire extinguisher always to be in the pits to deal with a burning battery.

Which classes use which pack

EFRA (Appendix 3, A 3.1 to 3.3; C 5): 1/12 at no more than 3.8 V nominal (from 1 March 2017; Appendix 4, 1.4 gives 1 April 2017 for 3.8 V cells), receiver batteries allowed; 1/10 touring, TC, FWD, Formula One and 1/10 off-road at no more than 7.6 V (LiPo) or 6.6 V (LiFe), receiver batteries not allowed; GT12 only from the 1S Stick Lithium Battery Homologation List.
IFMAR (March 2023, 3.8 and 3.15): 1/10 off-road, touring car and F1 use only 2S packs; 1/12 only 1S packs no larger than 93.0 x 47.0 x 18.5 mm. 1/12 and 1/10 off-road cars may carry an extra pack for the receiver and/or servo; 1/10 touring cars may not. Apart from the transponder's own battery no other batteries are allowed, and none may power the drive motor.
IFMAR 1/8 e-buggy (April 2023, 2.3): lithium-based packs of no more than 15.2 V nominal (4S), as one 4S, two 2S or four 1S packs, all the same brand and part number, from the blocs' approved lists shown on the IFMAR website; 4.20 V per cell and 16.80 V for 4S, checked before any run; batteries protected by the chassis or body and checked for deformity.
IFMAR 1/8 electric GTE (2025): at most 4S LiPo, in one pack or two equal packs, in a mandatory hard case, at most 16.80 V at the start of the race; the rule says any commercially available battery is allowed but also that for 2025 batteries must be homologated or approved, with a list available three months before an event, and that each battery may hold at most 100 Wh; over-voltage is penalised.

ROAR

ROAR's current rule book was not read, so its current battery rules are not known to this site. The only ROAR battery text read is section 8.3 of its rules as reprinted by LiveRC on 26 May 2011, which is historical:

approvals of new battery types are posted on roarracing.com, with ROAR's Executive Committee having final approval (8.3.1.1);
LiPo packs need a hard ABS or similar case fitted by the maker or distributor, with a "ROAR Approved" label across the seam (8.3.2.2);
cells rated 3.7 V nominal, packs 1S to 4S with parallel cells allowed (8.3.2.4); unless a class says otherwise the maximum pack is 2S 7.4 V (8.3.1.8); a 2S case no larger than 139 x 47 x 25.1 mm (8.3.2.3);
a Certification of Compliance showing the cells passed UN transport tests (8.3.2.1);
a maximum charged voltage of 4.25 V for 1S, 8.50 V for 2S, 12.75 V for 3S and 17.0 V for 4S, with no allowance for overage (8.3.2.5.2).

ROAR's rule book update of 18 October 2024 adds rule 11.2.1.14: makers alone are responsible for knowing when their battery approvals expire and need renewal. A LiveRC report from the 2015 ROAR Electric Off-Road Nationals says the race director required batteries to be charged in safety bags, banned intentional heating of packs, and disqualified drivers arriving at technical inspection with an overcharged or overheated pack; whether those remain ROAR rules is unconfirmed.

The BRCA

The BRCA's 2026 section handbooks and its Electric Recognition Board battery rules were not read, so no BRCA battery limit is given. The BRCA's Electric Board lists a 2017 document on lithium safety, which was not read.

Where the rules disagree

Receiver packs in 1/10 off-road. IFMAR (March 2023, 3.15) allows an extra receiver or servo pack; EFRA (2026, Appendix 3, A 3.3) says receiver batteries are not allowed.
Maximum charged voltage per cell. ROAR's 2011 text allowed 4.25 V per cell (8.50 V for 2S); IFMAR (2023) and EFRA (2026) cap LiPo at 4.20 V per cell (8.40 V for 2S). ROAR's current figure was not confirmed.
When a LiPo sack is required. EFRA (Appendix 3, A 3.4; Appendix 4, 2.4) requires LiPo and LiFe drive batteries to be in a sack whenever they are charged or discharged, except during a race or on organiser-supplied resistors, with a penalty for not doing so. IFMAR's March 2023 rule (3.11) speaks only of charging, in a closed sack at all times, on pain of disqualification. IFMAR's e-buggy book (2.3) uses EFRA's wording: charged or discharged.
EFRA's own two texts. EFRA's 2024 General Rules (5.3.12) say all racing batteries, car and radio equipment, whatever the material, must be charged in a sack, while the 2026 Appendix 4 (2.4) applies the rule to LiPo and LiFe drive batteries when charged or discharged. EFRA's 2026 General Rules were not read.

EFRA and IFMAR both define a LiPo sack as a receptacle designed for charging LiPo or LiFe batteries and built to contain a LiPo or LiFe fire. That is the rules' definition; it is not a finding that a sack prevents or contains a fire. IFMAR's e-buggy book (3.7.j) also says the organiser should provide fire extinguishers and buckets of water, because it is an electric event with LiPo batteries; that is a rule for organisers, not guidance for anyone else. More on battery rules at events.

Sources

Keep reading

Approved equipment lists

Every approved list the research found, body by body: EFRA's motor, battery, blinky ESC, bodyshell and muffler lists with their deadlines, IFMAR's yearly World Championship lists, ROAR's Approved List and who is responsible for it, and what was seen only by title.

Battery rules at events

EFRA's 2024 General Rules and 2026 Appendix 4, IFMAR's 2023 battery rules and e-buggy book, ROAR's 2011 text, the LiPo-sack rules as written, and three disagreements.

Batteries

Lithium polymer and lithium iron phosphate packs as racing rules name them: cell counts, nominal and charged voltages, hard cases, labels and UN 38.3, which classes use 1S, 2S and 4S, and the fire hazard as OSHA, UL and the CPSC describe it.