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The new J2601-5 hydrogen refuelling standard

Updated: 22 hours ago

In February 2024, SAE (Society of Automotive Engineers) published a new global fueling standard for heavy-duty hydrogen fueling. This standard, J2601-5, augments the existing J2601-1 standard with a set of fueling protocols that allow for safe and fast filling of heavy-duty vehicles such as buses and trucks. All hydrogen vehicles and refueling systems are universally designed to be compliant with the J2601 standards.


A fueling protocol such as J2601-5 defines how a dispenser must control hydrogen pressures and temperatures over the course of a refueling event. The fueling protocol specifies that hydrogen must be cooled to a specific temperature range during fueling, dependant on the specific protocol and the design of the dispenser. The fueling protocol considers environmental conditions, vehicle characteristics and other inputs in stipulating the fueling variables. The protocol also dictates operational limits, fault handling and other modes of operation such as slower fill rates, and incorporates real-time communication between the vehicle and the hydrogen dispenser when communication hardware is available.

The general fueling modes defined in the J2601-5 standard are as follows:

Fuel Pressure (bar)

Fuel Flow Rate Limit (grams/second)

Hydrogen Temperature Range (Celcius)



-40 to +20 (6 temperature categories)

700 - lookup table method

60 or 90

-40 to -17.5 (3 temperature categories)

700 - MC method

60, 90 or 300

-40 to 0 (5 temperature categories)

Note that the 300 grams per second flow rate will require newer dispensing components which are still in development.


This new “dash 5” protocol has two modes of controlling fueling: using a set of lookup tables to select a fixed pressure ramp rate and pressure target, or using a set of calculations (the “MC Method”) to calculate a dynamic pressure ramp rate and pressure target. The MC Method allows the fueling rate to increase dynamically if the dispenser is properly controlling the hydrogen temperature, thus allowing for faster fills. Conversely, if there are any issues with the system such that the hydrogen temperature is higher than normal, the MC Method automatically adjusts to a slower fill rate that allows the fueling process to continue uninterrupted while keeping the fill safe.

At Hyfluence, we have implemented both versions of this fueling protocol, to give the customer maximum flexibility in fueling options.


An interesting development that will affect the way fleets fuel their first few hydrogen vehicles is that according to the “dash 5” protocol, refueling vehicles using passive (non-cooled) mobile refuelers is no longer standard-compliant at publicly-accessible locations, and can only be used at a controlled private facility by a trained operator.

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