The highest power output alternator in its size/class - high output / high amperage alternator. A275L.
Ships to the lower 48 US states · Shipping details →
The ARCO Zeus A275L is a 12V high-output alternator that puts out up to about 310 amps. It is the upgrade for boats, vans and RVs whose lithium house bank needs far more charge current than the factory alternator can give.
ARCO’s ratings are at the alternator shaft, which spins faster than the engine (typically 2–3× through the belt):
| Peak, cold (9,000 alt RPM) | about 310 A |
|---|---|
| Sustained hot, cruising (6,000 alt RPM) | about 230 A |
| Sustained hot, idle (3,000 alt RPM) | 198 A |
| Starts charging at | about 1,060–1,080 alt RPM |
| Max continuous operating temperature | 230°F (110°C) |
| Weight | about 15 lb |
The hot numbers are the ones to plan around: an alternator always loses output as it warms up, and ARCO publishes its one-hour hot results rather than only the cold peak.
Sold here as External Only: it has no regulator of its own and will not charge until it is paired with an external regulator. To charge lithium safely and get full output, pair it with the ARCO Zeus regulator, which handles lithium charge profiles and battery temperature sensing. Read Can my alternator charge lithium batteries? before you choose.
Choose the housing that matches the alternator you are replacing:
| 1–2″ single foot | Most domestic single-foot alternators (e.g. Motorola, Prestolite). Needs a double-V or serpentine belt. |
|---|---|
| 3.15″ saddle | Most small-case saddle alternators (e.g. Hitachi, Lucas, Mitsubishi) and most Yanmars. Needs a serpentine belt. |
| 3.15″ saddle, rear-exit B+ (common rail) | Required on Yanmar common-rail engines after 2013 (JH-CR, 3JH40, 4JH45, 4JH57, 4JH80, 4JH110). |
| 4″ J180 saddle | Most Volvo Penta alternators with a 4″ J180 saddle. |
| N62 with clutch pulley | Mercedes Sprinter 1999–2006, and the factory second alternator on 2007-on Sprinters. |
Not sure? Send us a photo of your current alternator’s mounting feet and we will match it.
Like every Zeus alternator it is built in the USA by ARCO Marine of Pensacola, Florida, and is SAE J1171 certified (ignition-protected for marine engine rooms). Inside: a 16-pole rotor, a large-frame 138 mm stator, dual cooling fans and avalanche-rated diodes, with the rectifier outside the housing to keep heat away from it.
For a whole charging system rather than one part, see the Marine Charging Upgrade Kit, compare with a DC-DC charger, or ask the Power Guide. Call us on (410) 216-2907 with your engine model and we will confirm fit.
