Dual-Gun DC Fast Charger Power Allocation: Fleet Operator Guide

Direct answer: A dual-gun DC fast charger has one power cabinet feeding two output connectors. Vendors ship three different power-sharing models under the same “dual-gun” label, and the choice drives throughput and session time. Static Split fixes 50% per gun regardless of demand. Dynamic Allocation reshuffles current in real time by EV-reported maximum (needs ISO 15118 + OCPP 2.0.1J Smart Charging v2). Sequential Priority gives one gun 100% until taper, then shifts. HG Power’s Aurora Split 180 kW–2.6 MW and Genesis Integrated 40–480 kW support all three modes, firmware-switchable per order.

1. What is dual-gun power allocation and why fleets lose money on the wrong model

A dual-gun DC fast charger is a single power cabinet (the rectifier + control stack) feeding two physically separate output connectors — typically one CCS2 + one CCS2, or CCS2 + GB/T, or CCS1 + NACS depending on region. The cabinet’s rated power (120 kW, 180 kW, 240 kW, 360 kW, 480 kW, 720 kW etc.) is the maximum simultaneous power across both guns combined, not per gun.

How the cabinet divides that rated power between the two guns is the power allocation model. There are three canonical models in production use, and the choice determines three things fleet buyers actually pay for: average session time, kWh throughput per cabinet per day, and whether a single-vehicle session gets degraded by the hardware for no reason.

2. The three allocation models side-by-side

Each model uses the same hardware. The difference is firmware configuration plus — for Dynamic Allocation — the control loop between EV, charger, and CSMS. A buyer selecting the wrong model for the site profile overpays on cabinet count or underdelivers on session time.

3. Dynamic Allocation: how the current actually gets reshuffled

Dynamic Allocation is the model most fleet operators think they are buying when a vendor says “dual-gun 480 kW.” It works only when three signals are available every ~1 second:

1. EV-reported maximum current — the vehicle advertises its instantaneous current ceiling via CCS communication (ISO 15118-2 or DIN SPEC 70121). This ceiling drops as the battery warms, as SoC climbs past the taper knee (typically 55–80% SoC on a modern LFP or NMC pack), and when the BMS imposes thermal derating.
2. Charger-side current limit per gun — the hardware ceiling, set by the output cables (liquid-cooled 500 A vs air-cooled 200 A) and the connector rating (CCS2 500 A, MCS 3000 A).
3. CSMS-pushed charging profile — if the operator wants to cap total site power during a grid-signal event, the CSMS sends an OCPP 2.0.1J SetChargingProfile which bounds the cabinet-level allocator.

The cabinet controller takes the three inputs every control cycle and solves a straight constrained-minimum: deliver each gun the lesser of (EV max current, hardware limit, remaining headroom under the CSMS cap). Any power the EV is not pulling on Gun A is immediately shifted to Gun B.

4. Sequential Priority: the depot-charging dark horse

Sequential Priority gives 100% of cabinet power to the first-plugged vehicle until that vehicle tapers below a configurable threshold (typically 50% of cabinet rated power), then releases the headroom to the second gun. For a depot operator charging 10–20 trucks overnight on 5 cabinets, Sequential Priority delivers faster first-vehicle completion and a predictable staircase of session finishes, which simplifies dispatch.

Sequential is worse than Dynamic on sites with short-dwell random arrivals (public highway stop): the second car waits for the first to taper before getting meaningful power. Sequential is better than Static on depot sites because the first vehicle finishes 30–40% faster in the common case where only one gun is in use at a time.

5. The arithmetic: what fleet buyers actually get per cabinet per day

Below is an illustrative comparison for a 480 kW dual-gun cabinet under three allocation models. Assumptions: 50% light-duty vehicles with 150 kW peak accept, 30% medium-duty with 250 kW, 20% heavy-duty with 350 kW; 20 sessions per day distributed across both guns; 60 kWh energy target per vehicle; taper modelled at a typical 60–80% SoC knee. Actual site figures depend on vehicle mix, arrival distribution, and ambient temperature — site-specific modelling available on request.

The illustrative ~20% throughput gap between Static and Dynamic is the single largest hidden spec in the dual-gun purchase. On a 20-cabinet site over a 10-year operating window, a gap of this order compounds into either a measurable revenue delta or additional cabinets required to hit the same daily throughput target. Fleet operators should request vendor-run modelling against their actual vehicle mix before cabinet count is finalised.

6. OCPP 2.0.1J and ISO 15118 hooks that make Dynamic Allocation real

Dynamic Allocation is a communications feature, not just a power-electronics feature. The cabinet needs to know, every second, what each EV can accept and what the site operator wants to cap. That requires:

A cabinet shipped on OCPP 1.6J can run Static Split cleanly and Sequential Priority adequately, but Dynamic Allocation on 1.6J relies on vendor-proprietary extensions. The industry baseline for new builds is OCPP 2.0.1J + ISO 15118-2 — see our full OCPP 2.0.1 vs 1.6J procurement guide for the certification language to put in a tender.

7. Five dual-gun RFQ clauses to paste into every tender

8. HG Power dual-gun product matrix

HG Power manufactures 30–720 kW DC fast chargers and AC wallboxes with CE, TUV CB, UKCA, Australia RCM, ETL and ENERGY STAR certifications for regional distributors, fleet integrators and OEM buyers in developed markets. Dual-gun support is implemented in-house on a single firmware base; the active allocation model is agreed per order and switchable via OTA.

For a split-cabinet deployment with multiple dispensers off one Reactor (Aurora Split 720 kW and above), the Reactor’s shared power pool enables Dynamic Allocation at the dispenser-group level: headroom unused at one dispenser is available to others drawing from the same Reactor, subject to per-dispenser hardware limits. This is the configuration we recommend for highway and heavy-duty hubs. For broader market context see our pillar on how to vet an EV charger manufacturer in China, and the MCS megawatt platform overview for 1 MW+ dispenser-level deployments.

9. Reference deployment: 240 kW DC dual-gun at a Jordan commercial site

HG Power’s reference deployments include a 240 kW DC fast charger with dual-gun configuration at a commercial center in Jordan. The site serves a mixed vehicle profile (light-duty passenger vehicles and commercial sedans) at a retail destination. Specific session telemetry, cabinet model variant, and the active allocation model configuration are provided on request under NDA; publicly, the deployment demonstrates HG Power’s dual-gun DC capability in a developed-market retail charging context.

For deployment inquiries matching similar profiles — including allocation-model selection, CSMS integration, and OTA firmware support — see partner with HG Power.

10. References

11. FAQ

Does a “dual-gun 480 kW” charger always deliver 240 kW per gun?

No. 480 kW is the cabinet rating. Per-gun delivery depends on the allocation model and the EV-reported maximum current. Under Static Split both guns are capped at 240 kW even if one is idle; under Dynamic Allocation a solo vehicle can pull the full 480 kW limited only by its own BMS and the connector rating. Always ask the vendor which model is active and whether it can be switched by firmware.

Can I switch allocation models after the cabinet is installed?

On HG Power Genesis, Aurora, Deepsea, and Glacier platforms, yes — the model is a firmware configuration and can be switched via OTA with the operator’s CSMS. On some older cabinets built around a fixed controller the model may be set at manufacture; verify switchability in the RFQ before purchase.

Which model is best for a highway hub with mixed-vehicle random arrivals?

Dynamic Allocation. Random short-dwell arrivals mean the second car cannot wait for the first to taper (which Sequential requires), and Static wastes power whenever only one gun is in use. Dynamic delivers the highest cabinet kWh/day and the shortest average session for mixed traffic.

Which model is best for an overnight depot?

Sequential Priority. Depot operators care about predictable finish times for dispatch planning. Sequential gets the first truck done fastest, releases the headroom to the next, and avoids the ISO 15118 complexity if the fleet mix is uniform. Dynamic is also fine and gives marginal gains if arrivals are staggered.

Does Dynamic Allocation require ISO 15118 or will DIN SPEC 70121 work?

DIN SPEC 70121 reports current demand so the basic Dynamic loop works. The gains from predictive reallocation (anticipating the taper before it hits) and from CSMS-pushed site caps are only available on ISO 15118-2 + OCPP 2.0.1J. For new builds in 2026, specify the modern stack; DIN SPEC 70121 is a legacy fallback.

Can two different vehicle types (e.g. CCS2 and GB/T) share one HG Power dual-gun cabinet?

Yes, HG Power Genesis and Stellar DC regional variants ship with mixed connector configurations (CCS2 + GB/T common in Middle East and Southeast Asia). Dynamic Allocation works across different connector types because the allocation logic operates on current, not connector protocol.

What happens if the EV reports an unrealistic max current?

The cabinet enforces its own hardware ceiling: the lesser of EV-reported, connector rating, and cable rating. An EV requesting 1000 A on a 500 A connector gets 500 A. Any properly implemented ISO 15118-2 stack will not accept the mismatch and will negotiate down.

Reviewed by: Marvin Zhou, Head of International Marketing, Shenzhen Hongjiali New Energy Co., Ltd. · Last reviewed 2026-10-21 · References: OCPP 2.0.1 Specification (OCA, Edition 3, 2022-12); ISO 15118-2:2014; DIN SPEC 70121:2014-12; IEC 61851-23:2023; HG Power 2026 Product Selection Manual and 2026-09 Company Profile.