1.1.2 Alternator¶

Specifications¶

• Output: 270A continuous
• Voltage: 12V (standard automotive)
• Application: Cummins R2.8 engines
• Type: High-output welding alternator
• SKU: HO-C28

System Configuration¶

Primary Function: Charges START battery and powers vehicle electrical systems

Output Capacity: 270A continuous (exceeds system maximum draw of ~326A with margin)

Mounting: Direct bolt-on replacement for Cummins R2.8

Wiring¶

Ground Path: Alternator case → Engine block → Engine bay ground bus → START battery- (driver rear wheel well)

See START Battery Distribution for complete wire specifications (gauge, distance, voltage drop calculations).

Load Analysis¶

Alternator Capacity: 270A continuous

Worst Realistic Load: 218A (offroad scenario) = 52A margin (19% headroom)

The alternator supplies START battery loads plus BCDC charging. AUX battery loads (SwitchPros, ARB compressor, winch) do NOT draw from alternator.

See START Battery Load Analysis for complete scenario details.

Outstanding Items¶

• Determine alternator positive output terminal size (for 1/0 AWG lug selection) — see Vendor Inquiry below
• Verify alternator voltage regulator set point (14.2–14.4V is the correct AGM target;¹ confirm the HO-C28 actually regulates there) — see Vendor Inquiry below

Vendor Inquiry — Premier Power Welder (draft)¶

Both open items above are answered by one email to Premier Power Welder:

Subject: HO-C28 (Cummins R2.8 270A) — output stud size & regulator set point

Hi Premier Power Welder,

I'm wiring the HO-C28 270A alternator (Cummins R2.8) into a dual-battery
truck and need two specs to finish the install:

1. Output terminal: what is the thread/stud size of the positive output
   post? I'm sizing a ring lug for 1/0 AWG cable and want the correct
   stud diameter (e.g. 1/4"-20, 5/16"-18, M8, etc.).

2. Voltage regulation: what is the regulator set point, and is it
   suitable for AGM batteries (target ~14.2-14.4V at the battery)? Is the
   regulator internal and fixed, or adjustable? My START battery is AGM.

Application: HO-C28 on a Cummins R2.8 Repower, charging an AGM start
battery (~850 CCA).

Thanks,
[name]

Related Documentation¶

• Batteries - START battery specifications (850 CCA)
• START battery Distribution - Alternator charging destination
• Grounding Architecture - Alternator ground path
• Wire Distance Reference - Alternator to battery routing distance