E-foils, jetboards, scooters and Seabobs have long been standard equipment on many superyachts. However, with their lithium-ion batteries, the challenge of organising charging and storage safely is also growing. The Raclan Maritime Battery Safety System, or RAMBSS for short, is designed as a fixed, modular system for this purpose. Sealectric offers the solution for use on superyachts.
Three modules for different water toys
RAMBSS consists of three stackable modules, each with a base area of 600 by 600 millimetres. They are 500, 750 or 1,520 millimetres high. According to Sealectric, the largest compartment can also accommodate a Seabob with a permanently integrated battery. The permitted battery capacity is up to 5.25 kWh per module.
This is what sets RAMBSS apart from the compact Raclan box. These smaller, portable boxes are designed for batteries used in e-bikes, scooters and other compact devices. They can therefore also be a suitable solution for smaller boats where there is no need to secure a large water toy garage.
What happens during thermal runaway?
The critical scenario for lithium-ion batteries is thermal runaway, a self-perpetuating overheating process. RAMBSS is designed to limit the consequences of such an event within the sealed module. According to Lloyd’s Register These include temperature monitoring, the automatic shutdown of the charging process if the temperature becomes too high, an automatic shut-off and cooling system, and filters for toxic and flammable gases. The alarm signal can be forwarded to the on-board system.
In practical terms on board, this means that the battery and charger must not only be physically separated from sensitive areas. The charging point becomes part of a monitored safety concept. Furthermore, the MCA Guideline MGN 681 calls for, amongst other things, monitoring, warning systems and appropriate measures to prevent overheating in such areas.
Type approval granted for RAMBSS
The regulatory framework is particularly important for superyacht operators. According to the manufacturer’s latest information, type approval for RAMBSS has now been granted. This means that the modular system meets a key requirement for yachts 24 metres in length and above, for which the stricter requirements of the UK’s MGN 681 Amendment 1 will apply from 1 January 2027 become relevant.
MGN 681 requires lithium battery storage and charging boxes on UK-registered yachts to have UK Type Approval from a UK Nominated Body from this date onwards. According to the MCA, boxes already on board may continue to be used, although replacement with appropriately approved products is recommended.
The document issued by Lloyd’s Register for RAMBSS was initially a Design Appraisal Document dated 11 November 2024. It confirmed that the system can be designed as part of an MGN 681-compliant arrangement. According to the manufacturer, the Type Approval now granted adds the relevant product certification. For the specific installation, the requirements relating to flag, class, yacht code, size, tonnage and operational profile remain decisive.
For BOOTE readers who use lithium technology on a smaller scale, the fundamental question remains the same: Charging lithium batteries correctly and consistently remove any damaged or suspect energy storage units from normal on-board operation. In addition, BOOTE explains, Why lithium-based systems can pose a safety risk and how Have any burning lithium batteries on board extinguished.
What solution do you use on board to ensure the safe charging of Watertoy and equipment batteries, and how is it integrated into your alarm and security system?
Michael Rinck
Redakteur Test & Technik
