The lithium battery for your Fiat Ducato.
The Ducato is the van under most of the road. It carries the majority of UK coachbuilt motorhomes and a huge share of big panel van conversions, which means one battery answer covers a lot of ground. Whether you bought a finished motorhome or you are building out an empty Boxer, a drop-in DIN lithium replaces the tired lead-acid that came with it and gives you power you can actually use.
One platform, three badges, most of the motorhomes
The Fiat Ducato, Peugeot Boxer and Citroen Relay are the same van wearing different badges, built on the shared X250 and X290 platform. That one van sits under most of the coachbuilt motorhomes sold in the UK, from Bailey, Swift, Auto-Trail, Elddis and Bessacarr through to a long list of European builders, and it is the default base for serious panel van conversions too.
So the leisure battery question is the same whether you are upgrading a finished motorhome or kitting out a bare Boxer. The factory fits a lead-acid leisure battery that you can only safely half-empty before it starts to suffer. A TITAN DIN lithium drops into the same kind of space, gives you close to its full rated capacity every cycle, charges far faster, and is built to last the life of the van rather than a few seasons.
If you are starting from an empty shell, the van conversion guide walks through building around the battery. If you want the wider picture of living with lithium in a motorhome, start with the motorhome battery guide.
Sizing a Ducato, Boxer or Relay
A starting point by build type. Most factory motorhomes leave the line with a single 90Ah to 110Ah lead-acid, so even a like-for-like lithium gives you far more usable power.
| Build | How it gets used | Good fit |
|---|---|---|
| Compact PVC or weekenderLights, fridge, phones, the odd night off hook-up | Modest | 100Ah to 150Ah |
| Two-berth coachbuiltHeating, water pump, telly, a few days off-grid | Typical | 150Ah to 180Ah |
| Family coachbuiltMore lights and devices, longer stays, bigger fridge | Regular off-grid | 180Ah to 230Ah |
| Full-timer or inverter cookingLiving aboard, coffee machine, induction hob | Heavy, sustained | 230Ah to 460Ah |
These are starting points, not fixed rules. The honest figure comes from your loads, not the badge on the van, so total them in the battery size calculator. For bigger banks you can run matched packs in parallel or step up to a single larger battery where the locker allows.
Where it fits on a Ducato
On the Ducato platform the leisure battery usually lives in one of two places, and the flat DIN case suits both:
- Under the cab seat. Many coachbuilts site the leisure battery in a box under the passenger seat base. The low, flat DIN case is made for this, keeping the weight down and central. Our terminals sit low on the case to help clear the seat frame, which is tight on some swivel bases.
- In the rear locker or garage. Larger banks tend to live in the habitation locker or garage, with room to mount the charger and fusing alongside. This is the easiest home for a 230Ah or above.
Because it is sealed to IP67, the case shrugs off the damp you get in an underfloor or locker mount. The one caveat is the RJ45 comms ports, which drop to IP32 while a cable is plugged in, so keep connected ports clear of standing water. Under-seat voids and battery trays vary by model year and converter, so measure your existing tray before you order rather than going off a brochure figure.
Charging on the Ducato platform
A motorhome or conversion typically charges from three sources: the engine alternator, roof solar through an MPPT, and mains hook-up. Lithium takes all three happily and charges much faster than lead-acid, so a decent drive or a sunny afternoon puts real capacity back rather than a slow trickle.
The alternator is where the Ducato platform needs a little thought. Euro 6 vans, and the post-2021 Series 8 in particular, run a variable-voltage smart alternator that will not reliably fill a lithium battery on its own. The fix is a DC-DC charger, also called a battery-to-battery charger, and we would fit a Victron Orion every time. It gives the lithium a clean, controlled charge and protects the starter battery. A standard split-charge relay does work, but it is not the most reliable way to charge lithium and some relays cause a backfeed that quietly skims around the top 15% off your usable capacity. Feeding straight off the alternator with no relay and no DC-DC is not something we recommend.
Plan the roof with the solar guide, check your existing charger against the compatibility list, and size the battery around the gap your charging cannot cover. Every TITAN carries a custom BMS, charges safely down to -30C, and comes with a lifetime, fully transferable warranty.
