Battery-Electric vs Hydrogen Fuel-Cell Transit Bus Charging, Judged by Duty Cycle

If a hydrogen bus refuels in six minutes, why is anyone still ordering battery-electric transit buses? Because six minutes and several hours of charging are not the same measurement. One is a refueling window at a hydrogen dispenser. The other is a full charge on a depot plug, and each figure arrives with footnotes that decide where it applies.

This comparison stays with two named examples from New Flyer: the Xcelsior CHARGE FC, a hydrogen fuel-cell transit bus, and the Xcelsior CHARGE NG, a battery-electric transit bus. Every number below is a manufacturer statement about those specific models, not an independent test and not a specification for the whole category. Configuration, duty cycle and site conditions travel with each figure, and on a real procurement they move the answer more than the headline numbers do.

What the 370-Mile Fuel-Cell Range Actually Covers

New Flyer states that the Xcelsior CHARGE FC delivers up to 370 miles of range on a single refueling without off-board electric recharging, and attaches two asterisks to that sentence. The first says the range is achieved with a combination of normal fuel cell energy generation and battery-only mode. A fuel cell makes electricity onboard from hydrogen; battery-only mode means stretches of the route run off the pack with the fuel cell contributing nothing. The figure is a blended number for a hybrid powertrain, not a tank-to-empty result for a fuel cell alone.

The second asterisk narrows it further: the 370 miles is quoted when running a typical transit duty cycle with speeds below 50 mph. Duty cycle is the repeating pattern a bus actually works — how often it stops, how fast it runs between stops, how loaded it is, how long it idles and how long it sits at layovers. It is the transit equivalent of a driving schedule, and it is the only basis on which the published range is stated.

Read those qualifications as a perimeter. A block that stays on arterials and makes frequent stops sits inside it. A commuter express block holding highway speed mile after mile does not, and the cited material does not say what the range becomes there. Treat any highway-heavy assignment as outside the stated basis until the manufacturer restates the figure for that speed profile, and do not quietly discount the number to cover the gap.

The same page describes a large battery energy storage system that lets the fuel cell run under steadier conditions, helping reduce wear and hold consistent performance. Energy storage system, or ESS, is the onboard battery pack — the component that absorbs peaks and fills gaps so the fuel cell is not asked to follow every acceleration. Whether steadier operation actually extends stack life is the manufacturer's claim and is not independently measured here. What the description does establish is the architecture: a fuel cell sized for average load, a battery sized for peaks, and a range that depends on both.

Reading the 4.9-Hour Depot Charge for a 660 kWh Pack

On the battery-electric side the published anchor is different in kind. Depot charging for a full charge requires 4.9 hours for a 660 kWh ESS, according to New Flyer's material for the Xcelsior CHARGE NG. That 660 kWh is pack capacity: the total energy the onboard battery holds. A full charge means filling that pack from the state the figure was measured against, not topping up whatever is left when the bus rolls in at the end of a block.

A footnote under that line cites a 200A depot charger, notes that charging time varies by charger size, and prints 150kWh in the slot where a charger power rating would normally sit. Kilowatt-hours measure energy, not power, so that parenthetical cannot be read as a verified charger output and should not be converted into one. What survives the footnote is the useful part: the charger, not the bus alone, sets the clock.

Put those two statements together and the 4.9 hours becomes conditional in a way buyers need to hear. Feed the same 660 kWh pack from a smaller charger and the night stretches; feed it from a larger one and it shrinks, within whatever the pack will accept. Anyone quoting 4.9 hours as an inherent property of the bus is quoting a charger configuration along with it.

The figure is also a full-charge number, which makes it a dwell requirement rather than a layover option. A bus that needs the pack filled has to be parked roughly that long at that charger size. Anything short of that, where only partial replenishment is needed, is a different calculation the published material does not cover, and it should not be estimated from the 4.9 hours by simple proportion — the cited figures do not describe how charge acceptance changes across the pack.

Configuration matters as well. The 4.9 hours is stated for the cited model's pack and is configuration-specific data, not a fleet-wide constant. Build a schedule on the quoted figure and you have built it on one configuration; if the ordered configuration differs, the number has to be re-obtained rather than assumed.

Six to Twenty Minutes Against a Full Depot Charge

For the fuel-cell example, the refueling window is 6–20 minutes depending on the model and operating conditions, and the bus requires no overnight plug-in electrical recharging. That spread is wider than the headline suggests: the fast end and the slow end of the bracket are a scheduling variable, not a rounding error, and the manufacturer's own wording ties the window to model and conditions rather than to one guaranteed time.

Suppose a fleet runs two blocks a day with a forty-minute layover at a transit center, and suppose the refueling equipment sits at that center; a 6–20 minute refueling event then fits inside the layover with room for the driver's break. Nothing is gained from the window if the dispenser is at the garage instead; the bus still has to come home, and refueling becomes part of the overnight routine rather than the midday one.

Now suppose the opposite pattern: buses return once, in the evening, and sit for eight to ten hours before the morning pull-out. At that site the 4.9-hour full charge for a 660 kWh pack fits inside the dwell with hours to spare, and refueling speed has nothing to win. The pack refills while nobody waits for it.

The comparison people make — minutes against hours — is real but misapplied. The trade-off is where the refill time sits, not how many minutes it takes. Hydrogen's advantage lands in service, mid-day, at a dispenser. Depot charging's cost lands overnight, at a plug, when the bus earns nothing anyway. A fleet with long dwell and one pull-out a day is buying a capability it will not use; a fleet with tight midday turnarounds is buying the one thing it cannot do without.

The Depot Constraint That Decides Before the Bus Does

Before either powertrain is settled, the yard has to be settled. The first requirement that moves is the energy path into the site, not the vehicle: the cited fuel-cell example takes its energy as hydrogen, which has to be delivered and dispensed on site, while the cited battery-electric example takes it through a depot charger of the size behind its 4.9-hour figure. Those are different demands on the same piece of real estate, and they are not interchangeable.

Two questions follow, and they are the buyer's to answer because no datasheet contains them. Is there a refueling path the fleet can hold for the service life of the bus — hydrogen supplied and dispensed on site, at the rate the depot needs? And can the yard's electrical service carry the charging the depot schedule requires at the charger size quoted? Neither answer is in the cited material, and neither should be guessed from it. Utility capacity, hydrogen pricing, upgrade cost and construction timelines are site facts.

Sequencing is the part that trips procurements. A charger installation and a hydrogen supply arrangement both take time to put in place, and both sit upstream of the first bus arriving. Order the vehicles ahead of the energy decision and the fleet owns assets it cannot fuel. The published figures say what the bus can accept; they say nothing about what your site can deliver or when.

There is a boundary here that is easy to cross. Neither route is settled by a vehicle specification alone, because a specification describes the vehicle's interface, not the site's capability. A fleet can read every number on both sheets and still be unable to say which one it can operate, because the constraints that decide it live in the substation and the fuel contract.

Four Conditions That Decide It at the Depot Gate

Four conditions separate these two examples cleanly enough to act on, and each one carries the condition that makes it true.

If your blocks stay inside a typical transit duty cycle below 50 mph and a single refueling covers the day, that refueling window is doing real work for you. The condition is the range basis itself: the moment a block runs sustained speeds above 50 mph, the 370-mile figure no longer describes your service, and the conclusion has to be re-derived rather than carried over.

If your buses come back to a yard with hours of dwell and the charger on site matches the duty behind the 4.9-hour full charge, go with depot charging. That preference is conditional on the charger, not just the yard: the same pack on a smaller charger is a longer night, and a schedule that leaves no margin around the charge window is exposed by the first late return.

Skip the fuel-cell option if you cannot secure a refueling path. A refueling window is only an advantage where there is something to refuel from; without a supply arrangement on site, the six-minute number has no dispenser behind it.

Depot charging only closes if some bus in the fleet can sit through a full charge at the charger size behind the 4.9-hour figure. A full recharge cannot be compressed into a layover, and a fleet that never gives a bus that long at the plug has not bought the 4.9-hour capability; it has bought a bus that lives on partial charge.

In each of those four, the trade-off is commitment as much as timing: hydrogen commits the depot to a fuel supply relationship that has to keep working all year, and depot charging commits it to electrical capacity and to a timetable with enough dwell in it. Those are the two bills, and they are paid in different departments.

Different readers should weigh different parts of that. Schedule planners should weigh placement — whether the refill fits an existing layover or demands new dwell the timetable does not have. Buyers should weigh which site condition they can meet first, because one of the two energy paths will be ready sooner and the bus order follows it. Maintenance readers should weigh which system their shop can support with people, parts and diagnostic capability, since a fuel cell stack with hydrogen plumbing and a large battery pack with charging equipment are separate support problems, not two versions of one.

Questions to Put to the OEM Before Signing

Put these on the OEM question list in writing, because each published figure is quoted against conditions your route has to match. Ask for the range restated under your own speed profile, since the 370 miles is tied to a typical transit duty cycle below 50 mph, and ask what the number becomes on your express block.

Ask which charger size and which starting state produced the 4.9-hour full charge, and ask for the charger's power in consistent units, because the 150kWh parenthetical cannot be read as a power rating. A charger specification in kilowatts is the number an electrical engineer can design against.

Ask which models and operating conditions bracket the 6–20 minute refueling window, and what dispensing rate the ends of the bracket assume. A bracket that wide changes how a layover gets written, and a layover written on the optimistic end is a schedule that breaks.

Ask, finally, for both answers in the units your operation runs in: miles per block and hours per night, not miles per refueling in the abstract. A vendor who can restate both figures against your timetable has told you something no brochure does.

Fleets with neither a hydrogen supply path they can hold nor headroom in the yard's electrical service cannot close this comparison, and should not try to close it from either datasheet — neither sheet carries the deciding facts. Teams that already know how long their buses sit at the yard and how often a bus could be refilled can settle it at the depot gate, because the only question left is which refill window their own schedule can actually reach.