Marine battery sizing, comparisons and installation
Boat Batteries: The Australian Guide
Choose the right boat battery for your time on the water. Compare lithium and AGM marine batteries, calculate your house-bank capacity, understand installation costs, and plan charging and safety for Australian boating conditions.
Affiliate disclosure. Some outbound retailer links earn us a commission. It never changes what the calculator returns or where a brand lands in a comparison, and we hold no exclusive agreement with any battery company. Declared here, above the fold, as the ACCC expects — not in the footer.
Marine battery brands
Compare marine battery brands
Brands covered in our independent guides. Logos identify the brands; they do not imply endorsement or partnership. Scroll to explore.
Practical boat battery guides
Boat battery guides and installation tips
Useful observations, questions and checklists for the decisions between choosing a battery and leaving the berth.
Marine Battery Refit Quotes: Scope and Comparison Checklist
Ask each installer to mark what they intend to reuse. That is often where apparently similar quotes diverge.
Read battery guide →Before you buyBoat Battery Compartment Measurements and Layout Checklist
Make a full-size cardboard battery, including the terminals, before paying for freight.
Read battery guide →Energy planningBoat Battery Energy Log: Measure Weekend Power Use
The overnight reading is especially useful because solar is no longer masking consumption.
Read battery guide →Everyday loadsBoat Fridge Power Consumption: Measure Daily Energy Use
Measure the warm departure day and the settled second day separately.
Read battery guide →Compare usable battery capacity
Lithium vs AGM: usable boat battery capacity
Compare usable capacity and weight using your current calculator settings. These planning estimates assume 80% usable capacity for lithium and 50% for AGM; check the limits of the battery you choose.
128 kg
Off the boat
3.2 days
Refill on solar alone
Both banks are sized to cover the same net demand, with the same solar credit. The pale bar is what the label says; the solid bar is what the chemistry lets you take out in service — 80% on LiFePO4, 50% on AGM. Which is why the AGM answer is always the bigger, heavier number. Weights are pack weights at the selected system voltage.
Marine battery charging system
Boat battery charging: solar, alternator and shore power
This is the architecture we would argue for on any cruising boat: three charge sources, one lithium house bank, and a cranking battery that stays lead-acid and stays separate. The figures on the nodes are live from the calculator.
Boat energy use over 24 hours
Daily boat battery use and solar charging
Hour by hour, what your loads take against what the panels return. The gap between dusk and mid-morning is what the bank is for — and the reason we will not let a good solar day size it.
Peak draw, 9.1 Ah that hour
Best solar hour
Boat battery resources
Boat battery guides, calculators and comparisons
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Marine battery buying guide
Compare lithium and AGM boat batteries, estimate the capacity you need, and understand charging, installation, safety and insurance before buying.
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Boat battery sizing calculators
Calculate boat battery capacity, trolling motor runtime, alternator charging demand, solar charging and the lithium equivalent of an AGM bank.
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Marine battery brand comparisons
Enerdrive, Invicta, Revolution, KickAss, iTechworld, Amptron, Renogy AU. Spec tables, real-world caveats, and a verdict by use case rather than a single winner.
DC-DC charging, alternator protection, BMS behaviour, shore power, AS/NZS 3004.2, insurance and survey implications, ventilation and fire.
Warning signs, emergency priorities, five layers of system protection, a 32-point conversion checklist and links to current Australian authority guidance.
Nine hull types, each self-contained: the load profile, the recommended bank, a budget and a premium build, and what owners of that boat get wrong.
Boat battery questions
Marine lithium battery questions answered
Find answers about marine lithium battery costs, AGM comparisons, fridge runtime, alternator compatibility and Australian installation requirements.
Compare batteries for your boat
Marine battery brands: prices and comparisons
A single winner ages badly and makes a publication look bought. So every comparison ends the same way: a verdict by use case, and an honest note on where each brand falls short. The judgements are ours; the full spec tables live on the comparison pages and are re-checked each quarter.
Nothing in this table is sponsored and no brand sees it before publication. Product figures are manufacturer claims unless a complete independent evidence file is linked.
| Brand | Price band | What we like | Where it falls short | Best suited to |
|---|---|---|---|---|
| Enerdrive | $$$ | Deep Australian dealer and service network; documentation an electrician can work from. | You pay for the distribution. Rarely the cheapest amp-hour on the market. | Liveaboard |
| Invicta | $$$ | Marine-specific formats and an established Australian distribution channel. | Thinner retail presence outside the eastern seaboard. | Offshore |
| Revolution | $$ | Sensible middle ground on price with accessible telemetry. | Model changes can complicate a later bank expansion; confirm current compatibility. | Coastal cruising |
| KickAss | $$ | Strong value per amp-hour and easy to buy at short notice. | Specified for touring first; marine duty and enclosure are the owner’s problem. | Weekender |
| iTechworld | $ | Lowest entry cost we would still put on a boat. | Support is transactional. Claimed cycle life is not something we have verified. | Budget build |
| Amptron | $$ | Sizeable range, including formats that suit awkward battery compartments. | Documentation can vary between product generations; obtain the current datasheet. | Retrofit |
Boat battery facts and figures
Battery sizing by boat type
Recommended boat battery sizes by boat type
Typical house bank for the hull before your own loads are counted. Each page carries the load profile, the budget build, the premium build, and what owners of that boat get wrong.
From the editors
Independent marine battery advice for Australia
Most of what ranks for marine lithium in this country was written for caravans, or for America, or by someone with a warehouse to empty. None of those people are sizing your bank. So we set out to be the one source on the subject that sells nothing, owes nobody, and shows its working — on every page, in numbers you can dispute.
That means a few unglamorous commitments. We publish the honest downsides before any shortlist. We show the assumptions behind each calculator and label unverified specifications as claims. We compare by use case rather than naming a universal winner. And when a retailer link may earn a commission, we say so where you can see it.
If we ever stop doing those things, you should stop reading. Until then: work out exactly what your boat needs, then buy it from whoever you like.