Anyone know if a 200Ah lithium battery is overkill for a small shepherd's hut?

Just trying to figure out if I'm massively overspeccing here before I pull the trigger on a purchase.

Running a small shepherd's hut (about 18ft) as a glamping let. Loads are fairly modest — a few LED lights, a 12v compressor fridge, phone/tablet charging, and occasionally a small fan in summer. No inverter planned, keeping everything 12v to keep it simple.

I've been looking at a Fogstar Drift 200Ah because the price is genuinely hard to argue with, but I'm second-guessing myself. Would a 100Ah actually cover it comfortably? My concern is that guests will inevitably leave things on overnight and I don't want them waking up to a dead system.

Solar input will be two Renogy 200w panels going through a Victron MPPT, so recharging shouldn't be an issue on decent days — but we're in the UK, so "decent days" isn't exactly guaranteed November through February.

The way I see it:

• 200Ah gives a proper buffer for bad weather spells
• 100Ah is cheaper and lighter (weight matters on a hut with questionable floor joists)
• 200Ah means I'm probably only ever cycling 30-40% which should be great for longevity

Has anyone run a similar setup and found 100Ah was plenty, or did you end up wishing you'd gone bigger? Particularly interested if anyone's managed through a full UK winter without shore power backup.

LesKnight | 847 posts

@TerryScott72 200Ah lithium is actually pretty reasonable for a glamping let — I'd say it's sensible rather than overkill. Bear in mind guests won't be as conservative with power as you would be, and you don't want to be fielding complaints about flat batteries mid-stay.

The real question is what solar input you've paired it with. A 200Ah battery with insufficient panels is just an expensive way to run out of power slowly! What are you planning for charging — solar only, or do you have hook-up available as a backup?

Also worth factoring in whether guests might want to charge laptops, use hair dryers etc. Glampers can be surprisingly demanding! Better to have the headroom than be constantly babysitting the state of charge between bookings.

MoorRuss | 312 posts

My static caravan runs on 200Ah Fogstar and honestly some weekends I'm wishing I'd gone bigger — glamping guests have a remarkable talent for discovering loads you never knew you had. 🔌

KevWatson57 | 203 posts

Worth thinking about your worst-case scenario rather than average use. On my boat I learned the hard way that "modest loads" somehow always expand — guests especially are terrible for leaving things on charge overnight.

One thing nobody's mentioned: what's your recharge situation? Solar alone through a cloudy British November is a different conversation to having shore power as backup. If you're relying purely on solar, 200Ah lithium gives you decent autonomy through a few grim days, but I'd also look at what solar panel capacity you're pairing it with.

200Ah is probably about right honestly — 100Ah would have me nervous for a glamping let where you can't control guest behaviour, and 300Ah starts getting pricey without clear justification for your load list.

DevonDweller | 1,204 posts

@TerryScott72 One thing nobody's mentioned yet — usable capacity. With lithium you're typically working with 80-100% usable DoD versus maybe 50% for lead-acid, so that 200Ah is genuinely 160-200Ah you can actually draw on.

For a glamping let specifically, consider that guests are unpredictable. They'll leave lights on, charge multiple devices simultaneously, and potentially run a hairdryer despite the signage telling them not to.

I'd actually run a quick load audit: LEDs at ~10W, phone charging ~10W, maybe a 12V compressor fridge at ~40-50W average. Over 24 hours that's roughly 80-100Ah minimum. Add any USB sockets, a small inverter load, and your buffer disappears quickly.

200Ah isn't overkill — it's sensible headroom. The Fogstar Drift 200Ah is worth a look at that price point.

DodgyMechanic | 847 posts

What's your charging source though? That's the bit nobody's asked yet.

200Ah is fine on paper but if you're only running a single 100W panel you'll struggle to replenish it properly after a cloudy weekend — especially October through February when your glamping guests will be hammering the heating.

Done similar calculations for my garden office setup. Ended up with 2x 200Ah Fogstar Drift batteries precisely because I underestimated winter charging deficits, not loads.

@TerryScott72 what panels are you planning, and is there any mains hookup as backup? Makes a massive difference to whether 200Ah is sufficient or borderline useless in practice.

Also — what's the heating situation? If it's anything electric rather than gas/wood, your load figures will be completely different and 200Ah starts looking very marginal very quickly.