Is it too early to call this a restomod? Probably. But I'm taking an old boat and dragging its electrical system into the modern era, and the first big piece of that project is a brand-new lithium house bank. This is the opening move in a long build — a real look at the hard work that actually goes into owning, maintaining, and upgrading a boat, plus a close look at the gear that makes it possible.
In this kickoff I do two things: I unbox the LiTime 12V 320Ah Mini Smart lithium battery that's going to become the heart of the house bank, and I build a custom box to hold it in place before a single wire gets run. Both steps matter more than people give them credit for. The battery you pick defines what the rest of the system can do, and the box you build around it is the only thing standing between a very expensive cell and whatever the boat throws at it.
Why I'm Going Lithium in the First Place
I've lived with lead-acid house batteries long enough to know their tricks. They're heavy, they take up a mountain of space, and you only really get to use about half of what you paid for before the voltage sags into uselessness. Lithium fixes every one of those things — and after looking at the options, LiTime was the brand I wanted in the boat. They sent me this one to put through its paces, and so far it checks every box I care about.
Three things sold me:
It's actually powerful. Lithium holds its voltage almost flat across the discharge curve, so you get to use nearly the full capacity before anything drops out. That means this single 320Ah battery delivers more usable energy than two 8D lead-acids combined — and those 8Ds each weigh more than this thing does.
It's small and light. This is the "Mini" version, which runs about 30% smaller than a typical 300Ah lithium and roughly half the weight of three 100Ah lead-acids. On a boat where every pound and every inch matters, that's a big deal.
It's smart. Built-in battery management system keeps the cells from hurting themselves, and Bluetooth lets me pull up voltage, state of charge, and consumption right on my phone. No more guessing whether the bank is going to make it through another night on the hook.
If you're still on the fence about making the jump, I wrote a full breakdown of the lithium switch that walks through the trade-offs in more detail. And if you're keeping lead-acid a bit longer, getting your battery through the off-season is worth a read before winter hits.
Building the Battery Box
A $1,000+ lithium battery sitting loose in a bilge is a disaster waiting to happen. Slosh, vibration, stray tools, salt spray — pick your poison. Before I wire anything up, I want this battery living in a purpose-built box that's secured to the boat and sealed against the environment it's about to spend the next decade in.
I built the box out of marine plywood, cut to the exact footprint of the Mini so there's no shifting room inside. Then the whole thing got coated in West System Epoxy with the matching West System Hardener — two coats, inside and out, with extra buildup on the corners and anywhere water might sit. Epoxy is the difference between a box that lasts the life of the boat and a box that turns into mulch after two seasons. Don't skip it and don't cheap out.
Once the epoxy cured I hit the inside with Pettit EZ-Bilge as a finish coat. It's tough, it's bilge-rated, and any acid or coolant that might ever make its way in there is going to have a very hard time eating through it. The battery drops in snug, the lid seals down, and the whole assembly is now ready to get through-bolted to the boat and wired up in the next episode.
What's Next
The battery and the box are only half the equation. In the next part of this build I wire this lithium bank into the boat's existing system alongside the lead-acid starter bank, which means we're getting into DC-DC chargers, charging profiles, and the right way to keep two very different battery chemistries from fighting each other. If you're planning to add lithium without ripping out every lead-acid on the boat, that next piece is the one you don't want to miss.
If you're thinking about what other upgrades are worth doing while you've got the panels open, this list of smart boating upgrades is where I'd start.
Grab a LiTime of your own over at litime.com — use code JSA6 for 6% off — and the rest of the supplies are stocked at Defender Marine. See you in the next episode.
