Marine starting battery comparison
Century Marine Pro 780 vs Dual Force+ 31X MF
Dual Force+ 31X MF lists higher CCA and reserve capacity than Marine Pro 780, with the same 100Ah rating. It is an AGM model with a larger, heavier case. Compatibility, charging requirements and the intended cycling duty should determine whether that change suits your boat.
Specification-based comparison. We have not bench-tested these models. Prices are dated observations, not live offers. Read the manufacturer sources and editorial policy.
Which battery should you shortlist?
Option 1
Century Marine Pro 780
N70ZM MF / 133102
Consider the Marine Pro 780 when it meets the existing starting and accessory requirements and its case suits the installation.
Option 2
Century Dual Force+ 31X MF
31X MF / 148118
Consider 31X MF when its AGM characteristics and published ratings fit the application, with compatible charging and enough space for the larger case.
Battery specifications compared
Manufacturer-published figures, checked 2 October 2026. Missing or contradictory details are identified explicitly.
| Specification | Century Marine Pro 780 | Century Dual Force+ 31X MF |
|---|---|---|
| Exact model | N70ZM MF / 133102 | 31X MF / 148118 |
| Application | Starting and semi-cycling | AGM starting and shallow cycling |
| Rated voltage | 12V | 12V |
| Rated capacity | 100Ah at the 20-hour rate | 100Ah at the 20-hour rate |
| CCA at −18°C | 780A | 950A |
| MCA at 0°C | 1000A | Not stated in the cited table |
| Published reserve capacity | 180 minutes | 200 minutes |
| Dimensions (L × W × H) | 305 × 171 × 202mm; 225mm total height | 332 × 172 × 210mm; 232mm total height |
| Weight | 25.1kg | 28.5kg |
| Terminals | Twin; polarity D in manufacturer diagram | Standard / wing nut; check diagram |
| Published warranty | 24 months; conditions apply | Brochure lists 24/12 months by application; confirm terms |
Century Marine Pro 780: The brochure gives starting and semi-cycling specifications. Check the engine maker's battery requirements and the actual tray, restraints and terminal orientation; engine horsepower alone is not a fitment approval. Check manufacturer details ↗
Century Dual Force+ 31X MF: The website headlines 24 months; the marine brochure lists 24/12 months for starting/cycling applications. Confirm which warranty applies to your intended use. This model is included in Century's marine brochure even though its product page sits in the 4WD category. Check manufacturer details ↗
Australian prices and quote checks
Century Marine Pro 780
Current price not verified
The manufacturer brochure does not provide a retail price. Request a quote for the exact item number, including delivery and any fitting charge.
Check price source ↗Century Dual Force+ 31X MF
Current price not verified
Ask for a current quote for item 148118, including installation if required. No assumed price band is used.
Check price source ↗Source links on this page are direct references, not affiliate tracking links. Compare delivered prices on the same day and obtain a separate scope for installation, charging changes and protection.
Equal Ah does not make these identical batteries
Both list 100Ah, but their starting ratings and reserve figures differ. Capacity, starting current and reserve minutes describe different aspects of performance. Check the rating requested by the engine manufacturer rather than choosing whichever number looks largest.
The 31X MF is identified as AGM. A change in battery construction should trigger a review of the applicable charging instructions. Do not infer that any charger labelled for lead-acid is automatically configured appropriately for every lead-acid model.
Check the mounting and the extra mass
The 31X MF is longer and heavier than the 780. An apparently similar battery-box footprint can conceal a hold-down or access problem. Compare the actual tray and restraint to the supplied case and terminal orientation.
Reserve minutes are a laboratory rating, not a direct forecast of how long the boat's accessories can run. Preserve the required starting reserve and assess the actual duty cycle before relying on a single dual-purpose battery for repeated overnight use.
Warranty wording needs an application check
The 31X MF product page headlines 24 months, while the marine brochure lists different starting and cycling terms. Ask for the warranty statement applicable to the use being quoted. A headline warranty number is not the whole contract.
No current retail price is verified here. Compare supplied-and-fitted quotes, including any changes needed to the restraint or charging configuration. A brochure cycle-life claim is not an independent service-life comparison between these two models.
Common battery comparison questions
Is the 31X MF an AGM battery?
Yes. Century identifies Dual Force+ 31X MF as AGM in its product specifications.
Does its advertised 24-month warranty cover every use?
Confirm the application-specific terms. The marine brochure lists 24/12 months for starting/cycling, while the product page headlines 24 months.
Sources and comparison method
We matched the exact model codes to the manufacturer documents below on 2 October 2026. The selection advice is our interpretation of those specifications. We have not measured capacity, durability, waterproofing or service quality. We do not turn manufacturer cycle claims into a tested lifespan ranking.
Specifications, offers and warranty terms can change. Match the supplied unit to its current manual before purchase. Report a correction with the model code and source.