Narrowboat on the Kennet & Avon — is 200Ah lithium enough for winter liveaboard?

Coming at this from a van background rather than narrowboat, but the fundamentals don't change massively — and I'd say 200Ah is going to feel tight once you're dealing with short December days on the K&A.

The real killer isn't the headline capacity, it's your charging sources. On a van I can move to find sun; a liveaboard is often moored under tree cover or facing the wrong direction for days at a time. What's your solar array size, and are you relying on engine alternator to top up? Because if you're on a leisure mooring and not running the engine daily, you'll be crawling into that 200Ah pretty hard with heating, lighting, water pump, and any 240V appliances through an inverter.

A few things worth thinking through:

• Usable capacity — lithium gives you ~95% vs ~50% on AGM, so 200Ah lithium isn't as bad as it sounds on paper
• BMS behaviour in cold — some cheaper cells throttle charging below 5°C, which is very relevant on the K&A in January
• Shore power availability — does your mooring have a hookup point?

Personally I run a Victron SmartShunt alongside my Fogstar cells and the monitoring data alone has changed how I manage consumption. You really need to see your state of charge accurately before committing to a bank size.

Would be interested to know what your typical daily load looks like — heating system especially. Are you on a diesel Webasto/Eberspächer setup, or trying to run an electric heater off the bank? That answer probably matters more than the Ah figure itself.

@BoxerDream the K&A in winter is a different beast to van life though — you're not moving every day, which means your alternator time is unpredictable, and those canal-side trees will absolutely murder your solar yield from November through February.

I ran 200Ah LiFePO4 on my 57-footer for one winter and genuinely struggled once I added a diesel heating pump (the controller and fan draw more than people expect). Went to 300Ah the following season and felt the difference immediately.

Worth factoring in whether you've got shore power access at your home mooring — the K&A has some decent facilities. If not, a Victron MPPT paired with even a modest panel array will earn its keep on the occasional bright winter day when you'd otherwise be running the engine for domestic charging.

@BoxerDream @WattAMess25 both make fair points but the engine hours thing is the real killer — on the K&A in winter you'll be moored up for days at a stretch. 200Ah lithium sounds loads until your inverter's running a small heater or you've got a diesel heater fan, water pump, lighting all going simultaneously.

Done van builds with Fogstar cells and honestly I'd say 200Ah is okay for summer but I'd be looking at 300Ah minimum for winter liveaboard. Also worth factoring in a decent MPPT — Victron SmartSolar if budget allows — because even weak winter sun adds up over a full day moored on the towpath.

What's your charging setup beyond solar? Alternator via a B2B charger?

Been liveaboard on the cut for three winters now and 200Ah lithium is survivable but you'll spend an alarming amount of mental energy staring at your Victron BMV like it's the Countdown clock.

The K&A specific problem nobody mentions: those long lock-free stretches mean you can moor up beautifully for days

@PanelSteve "survivable" is doing a lot of heavy lifting in that sentence 😄

From my tiny house setup I run 400Ah Fogstar Drift cells and even that felt marginal through last January. On a boat you've also got bilge pump loads and potentially a webasto/eberspächer that'll chew through capacity faster than you'd expect.

If budget allows, I'd honestly look at doubling to 400Ah rather than faffing with a marginal setup all winter. Pair it with a decent Victron MPPT and even a small 200W panel will top you up on the brighter days.

The other angle — a DC-DC charger off the alternator while you're cruising is genuinely brilliant for keeping lithium happy without thrashing the engine at idle.