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A4000-24V LTO High Output Alternator

A4000-24V LTO High Output Alternator

Price range: $1,427.80 through $1,505.90

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Status: Instock

The ARCO Zeus A4000-24V alternator turns on at lower RPMs, runs cooler and provides more power than older designs that are larger and heavier. The newest generation of 24V performance has arrived.

Sale Price
Price range: $1,427.80 through $1,505.90
Total Price
Price range: $1,427.80 through $1,505.90

Ships to the lower 48 US states · Shipping details →

If Optimal Charging at Low Speed is Important to You, This is the Perfect Alternator for You

High Output / High Amperage Alternator: The Highest Power Output in Its Class

Note: if top-end cruising output matters more than charging at idle, see the ARCO Zeus A7000-24V.

24V Advantage – Low Turn On (LTO)

The ARCO Zeus A4000-24V LTO alternator turns on at lower RPMs, runs cooler and provides more power than older designs that are larger and heavier. This alternator continuously generates over 1.4kW (51 Amps) at just under 1,500 RPM, and almost 2.4kW (87 Amps) at 2,000 Alternator RPM. Put in real world terms, a marine diesel engine idling at 750 RPM with a 2:1 pulley ratio is generating over 1.5kW (55 Amps), and a Mercedes Sprinter at 750 RPM with a 3.21:1 ratio is generating over 2.5kW (91 Amps)!

Best-in-Class Performance

The ARCO Zeus A4000-24V alternator turns on at lower RPMs, runs cooler and provides more power than older designs that are larger and heavier. The newest generation of 24V performance has arrived.

True 24V Alternators

Competitor’s 24V alternators utilize a 12V rotor and field current which is less efficient and limits output at all RPMs. ARCO utilizes a native 24V rotor and field current. This results in our 24V alternator running cooler than competitor’s 24V alternators, having a direct impact on alternator lifespan.

ARCO Zeus 24V High Amperage Alternators, A4000-24V LTO or A7000-24V: Which One’s Right for You?

Choose A4000-24V LTO if:

  • You prioritize charging at idle (at campsite or anchor)
  • You need to limit power take-off i.e. smaller engine
  • You are willing to trade some top-end output for increased output
    at low RPMs

If these do not apply to you, see the A7000-24V.

  • Replace your noisy generator!
  • Engineered for high energy production.
  • Suitable for marine, RV, military, and commercial applications.
  • Rapidly charges large battery banks.
  • Coolest operating temperatures for increased performance:
    • Heat shedding coatings
    • Rectifier located on housing exterior
    • Dual cooling fans
    • OEM components
  • Optimized for performance at cruising speeds.
  • Reduces the need for a generator by creating additional power with your engine.
  • Unleash peak performance with E-Coat/Cerakote, keeping the high amp alternator cooler for sustained amperage output.
  • For maximum performance or lithium battery charging, use the ARCO Zeus Bluetooth Alternator Regulator.
  • Mercedes requires the use of a clutch pulley on secondary alternators used on all Sprinter vans. For Mercedes Sprinter, please use the N62 option with a clutch pulley.
  • SAE J1171 Certified.
  • Proudly made in the U.S.A.
Optimize your alternator’s output with the ARCO Zeus Bluetooth Alternator Regulator.

Voltage24V
Field TypeP
Rotor Poles16
Rotator Source Voltage24V
Stator Size138mm
Frame SizeLarge
Weight of heaviest option (N62 with clutch pulley)15.89 lbs / 7.2 kg
RegulationExternal Only (EX)
Finish(Black) E-coating
Cut-In RPM1,072 Alternator RPM
Maximum Alt RPM19,000
Battery PostM8 Thread Post, Side Mount
Standard Pulley49K6 (6-groove, 49mm)
Pulley Mount17mm diameter shaft, 25mm long, threaded M17 x 1.5
Pulley HardwareM17 x 1.5 x 24mm nut, w/ 18mm ID x 29mm OD washer (Included)
Diodes6 positive, 6 negative, 50A Rated, Avalanche
Max Output (Cold, 9,000 RPM) at 27.5V144 Amps – 3,960 Watts – 5.7Kw PTO
Sustained Cruising Output
(Hot, 6,000 RPM) at 27.5V
130 Amps – 3,575 Watts – 5.1Kw PTO
Sustained Idle Output
(Hot, 3,000 RPM) at 27.5V
108 Amps – 2,970 Watts – 4.2kW PTO
Max Continuous Operating Temperature100°C / 212°F



MountingARCO Part NumberApplication
1-2” Single Foot4405Replaces most domestic styles using a single 1” or 2” mounting foot (e.g., Motorola, Prestolite).
3.15” J180 Saddle4401Replaces most small case styles using a 3.15″ J180 saddle style mount (e.g., Hitachi, Lucas, Mitsubishi) Most Yanmars.
3.15″R Saddle Mount, Rear Exit B+4402Must Be used on Yanmar Common Rail Engines introduced after 2013 (JH-CR, 3JH40, 4JH45, 4JH57, 4JH80, 4JH110).
4” J180 Saddle4403Replaces most Volvo Penta alternators using a 4” J180 saddle style mount.
Vortec/GM4406Replaces Mando type alternators using Vortec/GM pad mounting feet. (Found on many Mercruiser and Volvo Penta 3.0GLM, 3.0GLP, 4.3GXi, 5.7GiL, 5.7GXiL Marine Engines).
N62 (Clutch Pulley)4404Replaces factory dual alternator on many Sprinter RVs, including Roadtrek, Thor, Winnebago, and others.
For all Mercedes Sprinter applications with N62 option.
Meets current Mercedes Upfitter weight and PTO requirements.

Isolated ground only for marine units.

External Only (EX): These units will come with a terminal block and a P-Type harness. They will only work with an external regulator, such as an ARCO Zeus Bluetooth alternator regulator.

To measure sustained output, the alternator is run at 3,000 RPMs for 60 minutes with a plexiglass shield covering the units. Testing shows that after 60 minutes in these conditions, alternators reach their maximum operating temperature, or the conditions under which the unit will produce the least output.

It is under these harsh conditions where we measure the “hot” output of the units at various RPMs.

Note: The “hot” conditions are much less favorable than the conditions typically used in the industry. The temperature of the stator during our “hot” test was 305 °F. Incumbents measure the power curve at an ambient temperature of 140 °F. “Cold” testing was done at 71° F.

ARCO Zeus 24V 4Kw LTOAPSMechmanBalmar
4401, 4402360HSB1H652S9E4––
440342I-270-14JEXT/STA––
4404360HN621H652S9CE4––
4405–––
4406–––



VoltageMaximum
Output (Amps)
Sustained Idle
Output (Amps)
HousingRegulationPulleyUnit Part #
24V144108Vortec (GM)External Only49mm K64406
24V1441081″-2″ Single FootExternal Only49mm K64405
24V144108N62 Clutch PulleyExternal Only50mm K6 Clutch Pulley4404
24V1441083.15″ J180External Only49mm K64401
24V1441083.15″ J180 Common RailExternal Only49mm K64402
24V1441084″ J180External Only49mm K64403



Ask us for the ARCO Zeus datasheet and wiring instructions – call (410) 216-2907 or email aps@apsoffgrid.com.

Product details

The ARCO Zeus A4000-24V LTO is a 24V high-output alternator built to charge well at low engine speed. LTO stands for Low Turn On: it starts producing power at lower RPM than a conventional high-output unit. That suits boats and vehicles that spend long periods idling or at low revs, and installations where belt load has to stay modest.

What it delivers

Ratings are at 27.5V and at the alternator shaft (engine RPM × pulley ratio):

Peak, cold (9,000 alt RPM) 144 A (about 3.96 kW)
Sustained hot, cruising (6,000 alt RPM) 130 A (about 3.58 kW)
Sustained hot, idle (3,000 alt RPM) 108 A (about 2.97 kW)
At 2,000 alt RPM about 87 A (2.4 kW)
Just under 1,500 alt RPM about 51 A (1.4 kW), continuous
Starts charging at about 1,070 alt RPM
Max continuous operating temperature 212°F (100°C)

As a worked example from ARCO: a marine diesel idling at 750 RPM with a 2:1 pulley ratio still gets over 1.5 kW from this alternator.

Regulation

This is an external-regulation alternator. It uses a native 24V rotor and needs an external regulator such as the ARCO Zeus regulator, which is also what lets it charge lithium correctly. Background: Can my alternator charge lithium batteries? and 24V vs 48V: which is right?

Which mount do I need?

Choose the housing that matches the alternator you are replacing:

1–2″ single foot Most domestic single-foot alternators (e.g. Motorola, Prestolite).
3.15″ J180 saddle Most small-case saddle alternators (e.g. Hitachi, Lucas, Mitsubishi) and most Yanmars.
3.15″ saddle, rear-exit B+ (common rail) Required on Yanmar common-rail engines after 2013.
4″ J180 saddle Most Volvo Penta 4″ J180 mounts, and many larger industrial-based engines.
Vortec / GM pad Mando-type alternators with Vortec/GM feet (many MerCruiser and Volvo Penta gas engines).
N62 with clutch pulley The factory second alternator on many Sprinter-based RVs.

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.

Planning a 24V system? Call us on (410) 216-2907 or start with the Power Guide.

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