Batteries by size
100Ah Lithium Boat Batteries: 12V Capacity and Runtime
These examples allow 80 Ah usable from a 100Ah battery using an 80% planning allowance. This is a reserve assumption, not a universal battery limit. Everything below is worked from 80 Ah, not from the number on the label.
On a single charge
100Ah battery runtime by appliance
Run times if that load were the only thing on the boat. Real boats run several at once, which is why the calculator sums them rather than letting you read a single row.
| Load | Draw | Run time on 80 Ah |
|---|---|---|
| VHF + AIS on standby | 0.9 A | 4 days |
| Fans | 1.2 A | 3 days |
| Cabin + nav lights | 2.0 A | 40.0 hours |
| Instruments + chartplotter | 2.2 A | 36.4 hours |
| Laptops, phones, tablets | 3.5 A | 22.9 hours |
| Freezer | 4.0 A | 20.0 hours |
| Autopilot (passage days) | 4.5 A | 17.8 hours |
| 12 V fridge (45% duty) | 5.0 A | 16.0 hours |
| Freshwater + shower pump | 7.0 A | 11.4 hours |
| Watermaker | 25.0 A | 3.2 hours |
Against real boats
Example overnight loads and battery bank capacity
| Hull | Daily draw | Nights on one 100 Ah | Cases for one night |
|---|---|---|---|
| 12 ft tinnie | 14 Ah | 5.7 | 1 case |
| Bowrider | 50 Ah | 1.6 | 1 case |
| Half cabin | 75 Ah | 1.1 | 1 case |
| Offshore centre console | 110 Ah | under one | 2 cases |
| Trailer sailer | 55 Ah | 1.5 | 1 case |
| 38 ft cruising yacht | 149 Ah | under one | 2 cases |
| Cruising catamaran | 260 Ah | under one | 4 cases |
| Houseboat | 320 Ah | under one | 4 cases |
| Liveaboard | 220 Ah | under one | 3 cases |
Daily draw is the load profile published on each hull page, quoted in 12 V amp-hours. Cases are the number of 100 Ah batteries needed to cover one night with nothing coming back in — before solar, and before the reserve you should be holding for weather.
The options
Compare listed 12V 100Ah lithium batteries
| Battery | Price band | Per usable Ah | Weight | Warranty | Bench |
|---|---|---|---|---|---|
| iTechworld 12 V 100 Ah | $450–$650 | $6.88 | 11.5 kg | 3 yr | claimed |
| KickAss 12 V 100 Ah | $550–$780 | $8.31 | 11.5 kg | 3 yr | claimed |
| Renogy AU 12 V 100 Ah | $600–$850 | $9.06 | 11.5 kg | 5 yr | claimed |
| Amptron 12 V 100 Ah | $680–$950 | $10.19 | 11.5 kg | 5 yr | claimed |
| Revolution 12 V 100 Ah | $700–$950 | $10.31 | 11.5 kg | 4 yr | claimed |
| Invicta 12 V 100 Ah | $900–$1,250 | $13.44 | 11.5 kg | 5 yr | claimed |
| Enerdrive 12 V 100 Ah | $950–$1,300 | $14.06 | 11.5 kg | 5 yr | claimed |
Pricing is indicative and not yet independently verified. Bands are compiled from published market pricing, not from quotes we obtained. No brand has paid to appear or be ranked.
At 24 V
A 24 V 100 Ah case holds twice the energy of the 12 V cases above, so it costs roughly twice as much and is not an alternative to them. It belongs on a boat already wired for 24 V.
| Battery | Usable energy | Price band | Warranty |
|---|---|---|---|
| Renogy AU 24 V 100 Ah | 2.05 kWh | $1,250–$1,700 | 5 yr |
| Invicta 24 V 100 Ah | 2.05 kWh | $1,850–$2,450 | 5 yr |
| Enerdrive 24 V 100 Ah | 2.05 kWh | $1,900–$2,500 | 5 yr |
Asked most
How long will a 100 Ah lithium battery last?
A 100 Ah LiFePO4 gives about 80 Ah usable using this site’s 80% depth-of-discharge planning allowance. On a boat drawing 3 A continuously that is roughly a day. The honest answer depends entirely on your loads, which is what the calculator is for.
Is 100 Ah enough for my boat?
On its own, 100 Ah covers a night at anchor for 4 of the nine hull types we publish load profiles for, including a 12 ft tinnie. Bigger boats need it multiplied: size the bank from your own loads rather than from a capacity you have already picked.
What does a 100 Ah lithium battery cost in Australia?
Indicatively $450–$650 at the budget end and up to $950–$1,300 for the marine-specific brands. Those bands are compiled from published pricing and are not quotes; confirm with the retailer.