Swapped out the leisure battery on my Transit camper – worth going lithium at this price?

Made the switch to lithium on my Sprinter last spring and honestly it's night and day compared to the AGM I'd been nursing along for three years. The usable capacity difference alone makes it worthwhile — you're not stuck at 50% depth of discharge with lithium, so a 100Ah battery actually behaves like 100Ah.

That said, "worth it at this price" depends entirely on what price you're actually talking about. Fogstar Drift cells have come down considerably, and if you're buying a proper LiFePO4 with a decent BMS rather than some no-name eBay special, the maths starts to make sense over a 5-7 year horizon.

Main things I'd check before committing:

• Is your existing charger lithium-compatible? A lot of older Transit/Sprinter habitation chargers will undercharge or worse, confuse the BMS
• Does your split charge relay or VSR actually work properly with lithium's flat discharge curve? Mine didn't, ended up needing a DC-DC charger (Victron Orion in my case)
• Temperature — LiFePO4 doesn't like being charged below 0°C, worth checking if you're doing winter trips

The upfront cost stings but I've not touched mine since installation. Contrast that with the AGM that needed topping up, desulphating, and eventually replacing anyway.

What capacity are you going for and what's your current charging setup? Those details would help people give more specific advice rather than just generic "lithium good" posts.

WildWanderer | Posts: 847 | Location: Peak District

@VitoProject totally agree on the usable capacity point – that 80-100% usable versus AGM's effective 50% is what sells it for me.

One thing worth mentioning for anyone on the fence: check your vehicle's alternator output before committing. Lithium charges so fast it can actually stress older alternators, particularly on higher mileage Transits and Sprinters. A decent DC-DC charger (B2B) between your starter and leisure battery is genuinely worth the extra spend rather than direct charging.

Also factor in the BMS protection – I've killed two AGMs by accidentally draining them too low over winter. Never had that issue with lithium.

What capacity did you go for in the end? I'm running 100Ah on my Vivaro which handles most two or three night stops comfortably without hookup.

SuffolkExplorer | Posts: 1,243 | Location: Suffolk

Worth adding that the chemistry matters considerably here. I run Fogstar Drift cells across three different setups — shepherd's hut, narrowboat, and a small cabin — and the cycle life figures are substantially better than cheaper LiFePO4 options I evaluated initially.

The one thing neither of you has mentioned: BMS quality. I've seen Transit and Sprinter builds where the battery itself is fine but the BMS trips under heavy inverter loads. What inverter are you running @VitoProject, and is it a Victron unit with proper comms integration, or standalone?

If the BMS can't communicate state-of-charge accurately to your charger, you're potentially damaging cells long-term regardless of brand.

The price drop on LiFePO4 over the past 18 months has genuinely changed the calculus — but a cheap cell with an inadequate BMS is still a false economy.

WattAMess27 | Posts: 312 | Location: West Yorkshire

Good thread this. One thing nobody's mentioned yet – check your alternator charging profile before assuming it'll play nicely with lithium. A lot of older Transits and Sprinters have smart alternators that throttle back voltage, which can leave you barely putting anything into a LiFePO4 during a long drive. Caught me out badly on my first install. Might be worth looking at a DC-DC charger (B2B) between the alternator and your leisure battery if you're doing serious mileage between hookups. @VitoProject did you sort alternator charging on yours or are you mostly relying on solar and hookup?

NicolaTaylor72 | Posts: 89 | Location: —

Really useful thread. I've been wrestling with this exact decision for my cabin setup and now considering the same for a small boat project.

Quick question for those who've made the switch — how are you finding lithium in cold UK winters? I've read that charging below around 5°C can damage the cells, and we're not always blessed with mild temperatures here obviously. Do you need a battery with built-in low-temperature protection, or is a heated battery compartment the more practical solution?

Also, has anyone compared Fogstar Drift against the Renogy lithium options at similar price points? The Fogstar seems popular on here but I'm not seeing many head-to-head comparisons for actual real-world van use.