Finally sorted my leisure battery bank after years of messing about — anyone else gone full lithium?

After three summers of nursing a tired 110Ah AGM around the Scottish Highlands, I finally pulled the trigger on two Fogstar Drift 100Ah LiFePO4 batteries wired in parallel last autumn. Total 200Ah for around £380, which still feels like a bargain compared to what lithium cost even two years ago. Running them through a Victron SmartShunt so I can actually see what's happening for once.

The difference is honestly embarrassing. I'm getting usable power down to around 10% without that horrible voltage sag that used to dim my lights and confuse the Truma. Parked up near Loch Lomond for five days last October — two 175W roof panels, barely any sun — and I never once worried about the fridge overnight.

I did have one head-scratcher though: my Victron MPPT 100/30 seemed to keep bumping the batteries to absorption even when they were sitting at 60% SoC. Took me an embarrassing amount of forum-reading to realise I'd left the charge profile on AGM defaults. Simple fix once I knew, but I wonder how many people are running lithium on the wrong profile and just not realising.

Has anyone else hit weird charging behaviour when first switching over, or found settings in the VictronConnect app that made a noticeable real-world difference?

Wendy1968 | 47 posts

Oh @ForestJenny, I completely feel this! I made the switch to a single Fogstar Drift 105Ah last spring after my old AGM kept leaving me stranded in Wales with a flat battery by day two. The difference is genuinely remarkable — I'm regularly using down to 20% without any anxiety now, whereas I used to panic below 50% with the AGM.

One thing worth mentioning that I don't see discussed enough — make sure your vehicle's alternator charging is sorted properly. I had to fit a decent B2B charger (went with the Victron Orion-TR Smart) because the standard split charge relay really doesn't play nicely with lithium chemistry. Took me an embarrassing amount of forum reading to figure that one out! 😅

Enjoy those Highland trips with proper power behind you! 🏴󠁧󠁢󠁳󠁣󠁴󠁿

Proper decision @ForestJenny — the Scottish Highlands will really put a leisure bank through its paces, especially those grey weeks where your solar panels are basically decorative!

I run a pair of Fogstar Drift 100Ah cells in my van conversion and the usable capacity difference versus AGM is almost offensive in hindsight. You're genuinely accessing 180Ah+ of what you paid for rather than nervously babying it down to 50%.

One thing worth checking early on — make sure your Victron (or whatever MPPT you're running) has the charge profile set correctly for LiFePO4. Sounds obvious but I spent a confused fortnight wondering why my Cerbo stats looked odd before spotting I'd left it on AGM profile. 🤦

How are you finding the weight difference in the van? That alone nearly made me emotional.

KenMitchell | 203 posts

Great move @ForestJenny — 200Ah usable is a completely different world to what you were running before. The real revelation with LiFePO4 for me wasn't just the capacity, it was how flat the discharge curve stays. You actually use what the spec sheet says you have, rather than watching voltage sag the moment you put any load on.

One thing worth double-checking with your parallel setup — make sure both batteries are at identical state of charge before you connect them together, and that your cable runs to each battery are the same length. Keeps the balancing tidy long-term.

What are you running for a charger/solar controller? The Fogstar Drifts are fairly forgiving but if your motorhome still has a older split-charge relay rather than a DC-DC charger, that's often the next thing worth sorting.

WD40Wizard | 341 posts

Different application here — I run mine in a static caravan rather than a motorhome — but the same principle applies. Made the jump to LiFePO4 two years ago and haven't looked back.

One thing worth mentioning that nobody's touched on yet: make sure your B2B charger or solar controller is actually set correctly for LiFePO4 charge profiles. Victron kit handles this brilliantly with the proper presets, but I've seen people damage cells early because they left it on AGM settings and never noticed.

@ForestJenny — with 200Ah usable you'll be genuinely comfortable in Scotland assuming your solar input keeps pace. What panels are you running up top? The Highlands in autumn can be... optimistic weather for solar yield 😄

My Fogstar Drift cells are still going strong after 18 months — the BMS on those things is tougher than my pension fund.

AGM_Pro | 87 posts

@ForestJenny interesting timing — I've been eyeing up the exact same Fogstar Drift setup for my narrowboat. Currently running a pair of 110Ah AGMs which are frankly embarrassing the moment I try to run the induction hob.

Quick question though — what charger are you using to top them up? I've got a Victron MultiPlus 12/3000 already fitted and I think the lithium charging profile on it is sorted, but I keep reading conflicting things about absorption voltage settings for LiFePO4.

Also wondering whether 200Ah is realistically enough if you're wild camping several days in a row with no hookup? I'm considering going 300Ah from the outset given I occasionally want to do EV charging from the boat's solar array too, which absolutely hammers the bank.