Upgrading the leisure battery in my old Transit camper — worth going lithium?

Made the switch from AGM to lithium in my shepherd's hut setup last year and honestly wouldn't go back. Running a 100Ah Fogstar Drift and the usable capacity difference alone makes it worthwhile — you're getting ~80Ah usable vs maybe 50Ah from a same-rated AGM without hammering the battery.

For a Transit camper the weight saving is a nice bonus too. My AGM was an absolute lump.

Few things worth thinking about though:

• Your alternator charging — lithium wants a proper DC-DC charger, not direct connection. Victron Orion is the go-to but adds cost
• Your existing solar controller — does it have a lithium profile? Worth checking before you buy
• Budget — Fogstar are good value for the money, but you're still looking at a meaningful outlay vs replacing like-for-like with AGM

If you're full-timing or doing long trips where reliable capacity matters, I'd say yes, worth it. If it's weekends here and there and your current setup mostly works… maybe less obvious.

What's your current solar/charging setup like? That'd help narrow it down. Anyone else here running lithium in a van conversion? Curious whether the DC-DC charger made a big difference day-to-day.

@HeatherGazer makes a solid point, but for a Transit the critical bit people miss is checking your alternator charging profile — most pre-2015 vans have a dumb alternator that'll happily cook a lithium BMS by just sitting at 14.4V indefinitely, so you'll want a decent DC-DC charger (Victron Orion-Tr Smart is the go-to) between the alternator and your lithium bank, otherwise you've spent £300 on a Fogstar Drift just to annoy it.

Key checklist before swapping:

• DC-DC charger fitted (non-negotiable)
• Mains charger lithium-compatible (check your existing unit)
• Fusing sized correctly for the new chemistry
• BMS low-temp cutoff awareness if you're wild camping in Scotland in January

Done properly it's transformative — done lazily it's an expensive lesson.

@OldSailor raises a really important point — has anyone actually had issues with the alternator charging side of things in a Transit specifically? I'm looking at doing something similar in my motorhome build and I keep reading conflicting stuff about whether you need a DC-DC charger (B2B) in between or whether some lithiums handle it okay directly.

Is the Fogstar Drift @HeatherGazer is running actually tolerant of alternator input without a Victron Orion in the mix? I assumed you'd always need one to protect the alternator from the lithium's low internal resistance essentially flooring it constantly.

What capacity did you go for — the 100Ah or did you stack two? Curious whether a single 100Ah would actually cut it for a longer trip without hook-up, or whether you'd be scrimping on things like the compressor fridge.

@JakeCrane yeah, had exactly this problem with my old Sprinter before I sorted the solar side of things properly. Standard alternator just dumps voltage into a lithium without a proper DC-DC charger and you're asking for trouble — either the battery BMS cuts out or worse, you're stressing the alternator itself.

Fitted a Victron Orion-Tr Smart 30A and it transformed everything. Isolates properly, charges at the right profile, can even set it up via Bluetooth which is dead handy.

For a Transit specifically worth checking what alternator you've got — some of the older Transits are on the lower end output-wise so factor that into your DC-DC charger sizing.

The lithium upgrade is absolutely worth it though. My usable capacity basically doubled overnight even before I touched the solar setup.

@OldSailor's alternator point is spot on — a B2B charger sorted mine a treat, and as a bonus my Fogstar Drift doesn't throw a tantrum every time the engine idles.