Kohler Decision-Maker 3500 — Mobile Paralleling Controller

Name: Kohler Decision-Maker 3500 Controller
Brand: Kohler
SKU: decision-maker-3500

Overview#

The Decision-Maker 3500 is Kohler's paralleling controller for mobile and mid-range commercial diesel generators. It brings multi-unit paralleling capability to towable Tier 4 Final platforms, allowing field crews to combine smaller units for larger loads or build N+1 redundancy at temporary facilities.

Generator compatibility#

Generator	Power	Application
35REOZT4	30 kW	Mobile trailer, Tier 4 Final
45REOZT4	40 kW	Mobile trailer, Tier 4 Final
55REOZT4	47 kW	Mobile trailer, Tier 4 Final
90REOZT4	85 kW	Mobile trailer, Tier 4 Final
145REOZT4	130 kW	Mobile trailer, Tier 4 Final
175REOZT4	150 kW	Mobile trailer, Tier 4 Final

Key capabilities#

Paralleling: Up to 8 units on isolated bus with automatic synchronization
Load sharing: Isochronous mode for proportional load distribution
Tier 4 integration: DEF level monitoring, SCR temperature, DPF regen status
LCD display: Runtime data, fault codes, and maintenance intervals
Modbus RTU: Serial communication for external monitoring or SCADA integration

OnPoint service notes#

On mobile trailer units, the Decision-Maker 3500 is the primary interface for technician diagnostics. Our crews verify synchronization timing and load share calibration during annual service. For paralleled deployments, we recommend commissioning verification whenever units are combined on a job site for the first time — synchronization timing and voltage matching must be confirmed under load.

Frequently Asked Questions

Which Kohler generators use the Decision-Maker 3500?

The Decision-Maker 3500 is standard on Kohler Tier 4 Final mobile trailer generators: 35REOZT4 (30 kW), 45REOZT4 (40 kW), 55REOZT4 (47 kW), 90REOZT4 (85 kW), 145REOZT4 (130 kW), and 175REOZT4 (150 kW). These are towable diesel units designed for temporary power, construction sites, and emergency deployment.

Can the Decision-Maker 3500 parallel multiple mobile units on a job site?

Yes. The DM3500 supports paralleling up to 8 units on an isolated bus with isochronous load sharing. This is commonly used on construction sites and emergency deployments where multiple smaller units combine to serve a larger load, or for N+1 redundancy at temporary facilities.

Does the Decision-Maker 3500 manage DEF systems on Tier 4 units?

Yes. The controller integrates with the Tier 4 Final aftertreatment system, monitoring DEF tank level, SCR catalyst temperature, and DPF regeneration status. It triggers alerts when DEF levels are low or when regeneration is required.

Key Terms

Tier 4 Final

The most stringent EPA emissions standard for off-road diesel engines, requiring near-zero particulate matter and NOx. Achieved through SCR (selective catalytic reduction) with DEF (diesel exhaust fluid) and DPF (diesel particulate filter) aftertreatment.

Isolated bus paralleling

A configuration where multiple generators synchronize and share load on a bus that is electrically isolated from the utility, allowing portable units to combine capacity on a job site.