High Output Alternator Performance Testing

Testing Performed by ARCO Marine Updated: 5/10/2024

•   Background and Overview 3
•   Testing Procedures and Results 4
-   Testing Equipment 4
-   Units Tested 5
-   Cold Power Curve 6
-   Low RPM Endurance Test 9
-   Hot Power Curve 10
-   High RPM Endurance Test 13
-   Warm Power Curve 14
•   Data Summary Table 16
•   Appendix 17

 

Background and overview

Testing Protocol:

ARCO internally developed tests to assess components for its high output alternator line. These tests are designed to identify the highest performing components, replicating real-world conditions for accuracy.

Comparative Analysis:

ARCO applies the same testing procedures to compare its new alternators with popular market models, ensuring a comprehensive evaluation of performance.

In-House Testing:

ARCO conducts all tests in-house, maintaining full control over the evaluation process.

Quality Assurance Measures:

ARCO takes all reasonable measures to minimize errors and biases, though the possibility of honest mistakes is acknowledged.

Transparency and Consistency:

Enhancing transparency and consistency in alternator testing benefits customers by highlighting the highest performing products.

Strategic Sampling:

Unable to test every alternator on the market, ARCO selects representative examples for comparison, all of which are new units.

 

ARCO Testing Equipment

Units Tested

•    ARCO Zeus A275L-12V
•    ARCO Zeus A225s-12V
•    Balmar XT250
•    Balmar XT170
•    Nations XP280
•    Mechman 250

 

Cold Power Curve Overview

Testing Procedure:

Alternator output is tested at 7 RPM speeds using a Motoplat CV-623A Alternator Tester.

Consistency Assurance: 

Tests are repeated on 3 separate days with overlapping RPM intervals to ensure data consistency.

Standardization Efforts:

Where possible, a uniform 44mm, 6-groove pulley is used to reduce variables, 
although variations exist in shaft diameter and pulley nut thread pitch. Where lack of compatibility prevented the installation of the 44mm pulley, the manufacturer’s original pulley was measured, used, and input into the tester to ensure accuracy of results.

Outlier Handling:

Clear outliers from the power curve data are removed for accuracy.

Controlled Environment:

Tests are conducted in a climate-controlled building with an ambient temperature of 
19-24°C, ensuring consistent conditions.  It is worth noting that minor discrepancies in ambient temperature can make minor impacts on “Cold” curves, while any such ambient temperature discrepancies make zero tangible impacts on “Hot” curves.

 

Cold Power Curve Results LARGE FRAME

ARCO A275L-12 at Idle:
The ARCO A275L-12V exhibited the highest amperage output at idle speeds.

 

Cold Power Curve Results SMALL FRAME

ARCO A225S-12 Outperforms:

The ARCO A225s-12V significantly outperforms similarly sized alternators across all speeds.

 

Operational Conditions: 

Alternators were run at 3,000 RPMs for 60 minutes beneath a plexiglass shield to simulate engine compartment conditions. During the 60-minute test, alternators typically reached 100°C, with temperatures inside the shield hitting 60°C.

Performance Trend:  

All alternators exhibited a significant output drop within the first 10 minutes, followed by a gradual decline over the next 20 minutes, stabilizing for the remaining 30 minutes.

ARCO A275L-12V Performance: 

The ARCO A275L-12V demonstrated the highest amp production at idle speeds. While initially matching the ARCO A275L's performance, the Balmar XT250 experienced a more pronounced output decline as it heated up.

Low RPM Endurance Tests		Amps
Time	ALT RPM	ARCO A275L	ARCO A225S	Balmar XT250	Mechman 250	Balmar XT170	Nations XP280
0	3,000	256	205	256	210	163	225
5	3,000	223	171	214	187	136	200
10	3,000	207	160	197	175	126	189
15	3,000	196	151	187	169	122	181
20	3,000	193	149	183	165	119	178
30	3,000	190	146	180	162	118	174
40	3,000	191	143	179	161	116	172
50	3,000	190	143	178	160	116	172
60	3,000	190	142	178	159	116	172

 

 

Hot Power Curve Overview

Simulation of Extended Idle Conditions:

The alternator undergoes a 60-minute test at 3,000 RPMs under a plexiglass shield, replicating prolonged idle speed conditions.

Power Curve Analysis: 

Immediately post-endurance test, the machine conducts 3 overlapping and redundant power curve tests, charting output at various RPMs.

Data Refinement:  

Overlaying the 3 power curves allows for outlier identification, with any clear outliers removed for accuracy. The resulting curve reflects the expected alternator output during extended periods at a given speed.

 

Hot Power Curve Results LARGE FRAME

Heat Build-Up:

Extended idle operation leads to significant alternator heating without adequate fan cooling, resulting in reduced performance.

ARCO A275L-12 Dominance:

The ARCO A275L-12V demonstrated superior performance, surpassing all alternators below 3,500 RPMs.

 

Hot Power Curve Results SMALL FRAME

Product Comparison:

The smaller ARCO unit, A225s-12V, was compared against a popular unit of
the same size, the Balmar XT170.

Performance Differential:

The ARCO A225s-12V boasts approximately 30% more power output compared
to the similarly sized Balmar XT170.

 

High RPM endurance test Overview

High-Speed Evaluation:

Each alternator underwent a 60-minute test at 9,000 alternator RPMs, catering to
those focused on performance at extreme speeds.

Enhanced Performance at High RPM's:

Higher RPMs result in increased alternator output, fan speed, improved air circulation,
and cooler alternator temperatures compared to idle speeds.

Performance Rankings:

For those prioritizing high RPM performance, the ARCO A275L-12V emerged as the top
performer.

 

High RPM Endurance Tests		Amps
Time	ALT RPM	ARCO A275L	ARCO A225S	Balmar XT250	Mechman 250	Balmar XT170	Nations XP280
0	9,000	312	245	295	260	185	265
5	9,000	252	208	243	224	164	236
10	9,000	248	198	235	216	158	229
15	9,000	247	196	234	214	156	227
20	9,000	247	195	231	213	156	226
30	9,000	245	194	231	212	154	225
40	9,000	244	194	130	212	153	225
50	9,000	244	194	228	212	152	225
60	9,000	244	193	228	211	152	225

Warm Power Curve Overview

Testing Performance:

Immediately after the high RPM Endurance test, which runs the alternator at 9,000
RPMs for 60 minutes, alternator output is evaluated at various RPMs.

Standard Effort:

All alternators are tested with a uniform 44mm, 6-groove pulley to eliminate
variables. Where lack of compatibility prevented the installation of the 44mm pulley,
the manufacturer’s original pulley was measured, used, and input into the tester to
ensure accuracy of results.

Data Refinement:

Three power curve tests are conducted, and the resulting curves are overlaid to
identify and remove outlier data points.

 

Warm Power Curve Results

Consistent Performance:

Performance across all units showed slight improvement but remained very similar to the results after an hour of running at low RPMs.

Low RPM Dominance:

The ARCO A275L-12V demonstrated the highest output at low RPMs.

 

Test Results Summary Table

	ARCO A275L	ARCO A225S	Balmar XT250	Mechman 250	Balmar XT170	Nations XP280
Max Cold Output	311	254	298	264	190	270
Max Warm Output (After High RPM Endurance Test)	246	197	232	213	152	200
Max Hot Output (After Low RPM Endurance Test)	239	189	217	199	145	216
1 Hour Idle Output (At 3,000 Alt RPMs)	198	151	188	167	122	180
1 Hour Cruising Output (At 9,000 RPMs)	249	198	218	216	156	228
Alternator Weight	15.27 Lbs.	12.45 Lbs. **Prototype	14.79 Lbs.	15.249 Lbs.	12.45 Lbs.	16.03 Lbs.
Turn on RPMs	1080	1196	1077	1268	1170	2432

 

Performance Comparison:

ARCO alternators outperformed units of similar size, delivering the highest
amperage at lower RPMs. The Nations XP280 required the highest RPMs for activation.

Appendix: Power Curve Samples

These results are from the second test of each alternator, referencing the original
test conducted on a different day for the same alternator.

Appendix: Power Curve Samples

Results were compared to the original test to confirm the absence of significant deviations. The second test served solely to validate the original test, utilizing data from the initial assessment.

Appendix: Testing Extreme RPM Ranges

Speed Range Extension:

The CV-623, originally set to test 7 data points from 1,800 to 6,000 alternator RPMs, was adapted with a false pulley ratio setting to capture more data across a wider speed spectrum.

Result Adjustment:

Following testing, the results were exported to Excel and recalibrated to align with the actual alternator speeds. The example below are cold power curves from an ARCO A275L-12V.

Appendix: Combining Data

The data from the previous page was converted into actual RPM values to ensure accuracy in analysis. Overlaying three distinct power curves, covering different yet overlapping RPM ranges, facilitates comprehensive result validation and aids in outlier detection.

Appendix: Power Curve Protocols

The three separate datasets are merged and sorted based on alternator RPMs,
streamlining the analysis process. Outlier points are systematically identified and
removed from the dataset to ensure data integrity.

Example:
The data point indicating 279 amps at 3,463 RPMs was eliminated as it was identified
as an outlier, despite being a positive outlier for ARCO.