Under-seat campervan LiFePO4 batteries: dimensions and low-profile models
SpaziouSpaziou Lab · physical compatibility
Under-seat campervan LiFePO4 batteries: dimensions and low-profile models
When the boot and cupboards are already full, the seat base may offer the best space for an auxiliary battery. We do not treat “mini” as a synonym for compatible: we compare millimetres, terminals, mounting orientation and manufacturer statements.
Spaziou rule: a casing smaller than the space does not prove the installation is valid. Allow room for terminals, wiring, fuse, fixing, ventilation and swivel-base movement.
The right question
Which battery fits the space you actually have?
There is no universal under-seat height for a Ducato, T5, T6, Transit or Sprinter. Generation, steel base, transformer installation, OEM wiring, heater, belt pretensioners and swivel bases vary. This page therefore separates two kinds of information: official battery dimensions and manufacturer-declared compatibility.
Length, width and height to the nearest actual obstruction.
Do not use all the height for the casing: allow space required for terminals, ventilation and maintenance.
Do not lay a battery down just to gain height: its exact model manual must permit it.
Verified matrix
Low-profile models worth measuring
| Model | Capacity | Dimensions L × W × H | Height | Spaziou status | What we know |
|---|---|---|---|---|---|
| Ultimatron ULS-12-100-LN3 | 100 Ah | 279 × 175 × 189 mm | 189 mm | ✓ Manufacturer | Ultimatron specifically describes it for under-seat installation in Fiat Ducato, Citroën and Peugeot. M8 terminals, IP65 and Bluetooth. |
| Super B Epsilon 12V100Ah | 100 Ah | 278 × 175 × 190 mm | 190 mm | △ Dimensional | DIN H6/LN3 casing. These are official dimensions, not a guarantee of compatibility with every seat base. |
| Super B Nomada 12V105Ah | 105 Ah | 437 × 90 × 175 mm | 175 mm | △ Very low profile | Particularly narrow and low. Super B primarily describes it as a system battery, rather than a standalone unit: design the complete system according to its documentation. |
| Roamer 230SEATBASE5 | 230 Ah | 285 × 331 × 182 mm | 182 mm | ✓ Swivel seat | Roamer designs it for seat bases and lists installations in VW T5/T6/T7, VW Crafter and various Fiat/Vauxhall/Renault vans, among others. |
These dimensions come from manufacturer data sheets consulted in September 2026. Seat-base reinforcements, connectors or equipment may reduce usable space. “Dimensionally compatible” does not mean “installation verified”.
Ducato / Boxer / Jumper
The most direct LN3 option
The Ultimatron ULS-12-100-LN3 measures 279 × 175 × 189 mm and is explicitly marketed as an under-seat battery for Fiat Ducato, Citroën and Peugeot. That is stronger evidence than a simple dimensional match.
Official Ultimatron data sheet ↗
View Ducato guide ↗VW T5 / T6 / T6.1
When 18.2 cm changes the project
The Roamer 230SEATBASE5 is 182 mm high and designed around a swivel base. Its manufacturer explicitly lists installations in VW T5/T6/T7, but you should still measure your seat and check the exact setup.
View VW T5/T6 guide ↗Do not rely on “Mini”
A compact battery can still be too tall
Amazon and manufacturer catalogues list many batteries as Mini or Xtra Mini. The name indicates reduced volume, not a guaranteed maximum height. A 208–227 mm battery may be small compared with a traditional casing yet still not fit a space with 190–200 mm usable height.
For general commercial products, keep this page open and check exact-version dimensions in our LiFePO4 battery comparison. Never buy from the advert photo alone.
Can I reduce height by laying it down?
Only when permitted by the manufacturer
LiFePO4 chemistry does not automatically make any battery suitable for side mounting. Victron allows upright or side mounting in its Lithium Battery Smart range, but prohibits downward-facing terminals and excludes the 12.8 V/330 Ah model, which must remain upright. Other manufacturers may impose different rules.
AGM batteries vary too: some sealed models allow side mounting under specific conditions, while other manuals require upright installation. Decide according to exact model + exact manual, not by chemistry.
Guide: mounting a battery on its side ↗Under-seat checklist
What to measure besides the battery
- Height of fitted posts and terminals: do not measure just the casing.
- Cable bending radius: a thick cable cannot exit at an impossible angle against a metal rail.
- Swivel base: check the full movement, not just the driving position.
- Fixing: a heavy battery must remain secured during braking and a crash.
- Fuse and isolation switch: decide where they go before filling the compartment.
- Temperature: check charge/discharge limits and low-temperature protection.
- Access: if the seat must be removed for every maintenance task, include that in the design.
Complete the installation · Amazon
Cable, protection and tools before closing the seat base.
JatilEr · 16 mm² · 50 cm · M8
May suit very short under-seat runs if calculations and the manual permit 16 mm². Do not use it as the default for large inverters or DC-DC chargers.
VEXUNGA · MEGA/ANM 125 A
Fuse holder with exact ASIN to illustrate the format. 125 A is not a universal recommendation: the rating must protect the cable and comply with the equipment requirements.
HX-50B · crimping tool 6–50 mm²
For battery and distribution terminals. Check that the crimping die matches the exact cable and terminal.
Victron Battery Switch · 275 A
Manual battery-bank isolation where layout and space allow. This is a switch, not overcurrent protection.
Plan these items before measuring final usable space. Battery, terminals, fuse, cable exit and swivel base must coexist without rubbing or excessive bends.
Technical sources
Data used
Ultimatron ULS-12-100-LN3 ↗ · Super B Epsilon 100Ah ↗ · Super B Nomada 105Ah ↗ · Roamer 230SEATBASE5 ↗ · Victron Lithium Battery Smart manual ↗.
Follow the pathway
Two formats to consider for under-seat installation
LiTime and Power Queen offer products for auxiliary installations. Fit depends on the seat base, vehicle generation, permitted orientation and available space; these options do not certify compatibility with your van.
LiTime 140 Ah H190 Bluetooth
H190 format for installations with limited height. Also measure terminal clearance, fastening and cable space.
View LiTime 140 Ah ↗
Power Queen 140 Ah H190 Bluetooth
Check the H190 140 Ah variant in the shop. SPAZIOU code: verify the discount and whether it combines with other promotions at checkout.
Explore the official Power Queen shop ↗
