How to Compare Marine Lithium Battery Specifications

How to Compare Marine Lithium Battery Specifications: steps

Convert label capacity to usable energy
Multiply amp-hours by nominal voltage to get watt-hours, then take 80% of that, because you cycle LiFePO4 to 80%. A 100 Ah 12.8 V case holds 1,280 Wh and gives you about 1,024 Wh.
Divide price by usable kilowatt-hours
This is the comparison figure. It puts a 24 V case and a 12 V case on the same axis, which dollars per amp-hour cannot do — an amp-hour at 25.6 V is twice the energy of one at 12.8 V.
Read the BMS specification, not the brochure
Look for the continuous discharge current, the low-temperature charge cut-off, and whether the BMS communicates or simply disconnects. A BMS that silently opens under load is a very different product from one that warns you first.
Check the terminals and the footprint against your battery box
Case dimensions, terminal type and terminal position decide whether the bank physically fits and whether your existing cable can reach without strain. This is a common and expensive surprise.
Weigh the warranty by who honours it
A ten-year warranty from a brand with no Australian presence is a shipping quote, not a warranty. Ask where a failed case goes and who pays the freight.
Discount claims nobody can verify
Cycle-life figures quoted without a depth of discharge and a temperature are marketing. Treat unverified pricing and unverified specifications the same way: as a claim, until someone independent measures it.

Ranking on price per amp-hour across mixed voltages.

Use dollars per usable kilowatt-hour, which is voltage-neutral.