In short
The BS1940 is the only series on this site certified to VDMA 24994:2024-08 — the specification that tests a thermal runaway started inside the cabinet. Six sizes, 2,500Wh to 22,500Wh total capacity, with a control unit that cuts charging power and raises an alarm on overheat.
If you have read our comparison of the three standards, this is the range that answers the question that actually matters: what happens when a cell fails on the shelf. The manufacturer publishes both directions of fire performance, which is unusual and worth having.
What it is certified to
| Fire, inside to outside | VDMA 24994:2024-08, certified by ECB.S, for a maximum shelf capacity of 2,500Wh (BS1941–BS1945) or 4,500Wh (BS1946), and total capacity from 2,500Wh to 22,500Wh depending on model. |
|---|---|
| Fire, outside to inside | Factory tested to EN 14470-1 for 90 minutes. NT Fire 017-120p certified for 120 minutes — stated as tested in the base model. |
| Impact | Fire and impact tested from 9.1 metres, for resistance to falling through the burning floors of a building. |
| Security | UK Police approved under the Secured by Design scheme. Reinforced multipoint locking. |
| Control system | CE certified. |
| Labelling | ISO 3864, ISO 7010 and European directive 92/58/EEC. |
The six sizes
| Model | External H×W×D | Internal H×W×D | Total capacity | Per shelf | Volume | Weight | Shelves | Doors | Power outlets |
|---|---|---|---|---|---|---|---|---|---|
| BS1941 | 855×690×710mm | 450×510×400mm | 2,500Wh | 2,500Wh | 91 L | 185kg | 0 | 1 | 1 × 4-gang |
| BS1942 | 995×690×710mm | 590×510×400mm | 5,000Wh | 2,500Wh | 120 L | 213kg | 1 | 1 | 2 × 4-gang |
| BS1943 | 1385×690×710mm | 980×510×400mm | 7,500Wh | 2,500Wh | 199 L | 261kg | 2 | 1 | 3 × 4-gang |
| BS1944 | 1610×690×710mm | 1205×510×400mm | 10,000Wh | 2,500Wh | 245 L | 388kg | 3 | 1 | 3 × 4-gang |
| BS1945 | 1910×690×710mm | 1505×510×400mm | 12,500Wh | 2,500Wh | 307 L | 416kg | 4 | 1 | 5 × 4-gang |
| BS1946 | 1910×1125×710mm | 1505×945×400mm | 22,500Wh | 4,500Wh | 569 L | 610kg | 4 | 2 | 5 × 8-gang |
Work out your own total in watt-hours before reading this table — see capacity and watt-hours explained. Note that there are two limits, not one: a total for the cabinet and a maximum per shelf. A cabinet with enough total capacity can still be wrong if your packs will not distribute across the shelves within the per-shelf figure.
Monitoring and control
This is the part that distinguishes the series, and it addresses the point made on what causes thermal runaway: cells vent gas before they flame, so early warning is worth more than containment alone.
- Internal temperature monitor as standard, with an external warning lamp. On excessive internal heat the control unit cuts power to the chargers and sounds an alarm.
- Siren and strobe triggered on overheat or thermal runaway. Charging does not resume until the cabinet is back in its normal range.
- Fire alarm connection — the control unit can be wired into the building system, which is what gets the fire service called at 3am rather than at 7am.
- Door sensors with a buzzer, so a door left open is noticed.
- Ventilation: air exhaust duct fitted as standard. The manufacturer strongly recommends dedicated ducting to outside for extraction during thermal runaway — read that as a requirement rather than an option, and see charging cabinets.
- Shelving: reinforced, insulated and height adjustable, rated at 100kg each.
- Construction: double wall with a patented Styronite F insulating fill.
Options worth asking about
An internal temperature and humidity monitor that links to a phone app and alerts on a set threshold; and condensed aerosol fire suppression formulated for lithium-ion. Neither is standard.
Locking
Three options across the range: K a key lock supplied with two keys; E a high-security electronic lock with dual control, hidden and scrambled code, upgradable to a multi-user audit trail; F a touchscreen keypad and fingerprint lock for up to 32 fingerprints. An audit trail is worth specifying where you need to show who accessed the cabinet and when.
What it is suitable for
Storage and charging of lithium-ion batteries up to 25kg each — power tools, garden tools, e-bikes and e-scooters, drones, laptops and phones. Two year materials and labour guarantee. A plinth is included so the cabinet can be moved out of the building during a fire.
Frequently asked questions
Is this cabinet a legal requirement?
No. No UK regulation requires a battery cabinet of any kind. What the law requires is that you assess the risk and control it so far as is reasonably practicable — see regulations. A cabinet certified to a standard that tests the failure mode you are worried about is good evidence that a control does what you claim, which is a different and more honest argument than saying it is mandatory.
What does the VDMA 24994 certification actually cover here?
Certification is tied to capacity, not just to the cabinet: ECB.S certified it for a maximum shelf capacity of 2,500Wh on the BS1941–BS1945 and 4,500Wh on the BS1946, and for total capacities from 2,500Wh to 22,500Wh by model. Load it beyond those figures and you are outside what was tested. That is why the per-shelf column in the table matters as much as the total.
Do I need to duct it to outside?
An air exhaust duct is fitted as standard, and the manufacturer strongly recommends dedicated ducting to outside for extraction in the event of thermal runaway. Vented cell gas is both flammable and toxic, so where the cabinet sits in an occupied space we would treat external ducting as part of the installation rather than an upgrade. It is one of the reasons this range is usually a survey rather than an online order.
How much does it cost?
We do not publish prices here because they date quickly and because the installed cost depends on ducting, power supply and siting rather than on the cabinet alone. For a figure you can put in a budget, ask for a specification review — the answer will come with the assumptions attached.
Specifications on this page are taken from the manufacturer’s published specification sheet for the BS1940 series. Where the sheet does not state a figure, this page says so rather than estimating.
| Brand | Phoenix Safe Company |
|---|---|
| Model | BS1941–BS1946 |
| Fire resistance | 90 minutes outside to inside (EN 14470-1, factory tested); 120 minutes to NT Fire 017-120p in the base model |
| Tested to | VDMA 24994:2024-08, certified by ECB.S |
| Capacity (Wh) | 2,500 (BS1941) to 22,500 (BS1946) total; 2,500 per shelf, 4,500 on the BS1946 |
| Dimensions (H×W×D mm) | 855×690×710mm (BS1941) to 1910×1125×710mm (BS1946) |
| Doors | 1, or 2 on the BS1946 |
| Charging outlets | One 4-gang PDU (BS1941) to five 8-gang PDUs (BS1946) |
| Charging version | Available |