Editable DC examples
12 V dual battery wiring diagrams
Follow the starter battery’s charging path to a separate auxiliary or leisure bank, then its protected load circuits. Choose an Orion XS B2B layout or a REDARC BCDC1240D example for a 4WD dual battery setup.
Orion XS B2B charging
6 components · 10 conductors · 12 V house system
Solid red = positive · dashed dark = return. Shared routes show both styles. Cable IDs match the schedule. Only connected terminals are drawn; crossings are not junctions. Scroll the drawing sideways on a small screen. Read the assumptions before adapting it.
Protection is unfinished. The shown fuse ratings do not select an exact protective device or locate it at the battery. Battery-end placement and unspecified-fuse warnings remain in Crimp. All charging and load currents below are design allowances, not measured operating currents.
Current engine findings
The blade-fuse interrupt check uses the engine’s chemistry-based fault-current assumption. This is not measured fault current. Resolve the bank and protection design before installation.
Check the exact fuse, holder and battery evidence →- critical: ATC fuse can't interrupt this battery's fault current (C3)
- critical: ATC fuse can't interrupt this battery's fault current (C5)
- warning: Fuse on House / auxiliary bank+ is too far from the battery (C1, C9)
- warning: Fuse on AGM starter bank+ is too far from the battery (C7)
- warning: House / auxiliary bank (LFP) has no fuse on the positive post (system)
- warning: 2 fused runs don't say which type of fuse (C1, C9)
Cable table — every displayed connection
Each length is one way. Drop is the engine’s run estimate including return, not a measured end-to-end system result; shared legs can have different conservative design-current bounds. “Pinned” marks a manufacturer-based example choice to review after edits. AWG is approximate; retain the stated conductor area when selecting actual wire.
| Circuit / endpoints | One-way length | Conductor | Design current | Fuse | Drop / allowance |
|---|---|---|---|---|---|
| C1 · House / auxiliary bank + ↔ Blue Sea 5026 ST Blade Fuse Block IN + | One-way length1 m3.3 ft | Conductor4 mm²AWG 11 · 45 A table | Design current10 A | Fuse15 A | Drop / allowance0.73% / 3% |
| C2 · House / auxiliary bank − ↔ Blue Sea 5026 ST Blade Fuse Block IN − | One-way length1 m3.3 ft | Conductor4 mm²AWG 11 · 45 A table | Design current10 A | FuseUnfused return | Drop / allowance0.73% / 3% |
| C3 · Blue Sea 5026 ST Blade Fuse Block 1 + ↔ Cabin lights + | One-way length3 m9.8 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current2 A | Fuse3 A | Drop / allowance1.17% / 10% |
| C4 · Blue Sea 5026 ST Blade Fuse Block 1 − ↔ Cabin lights − | One-way length3 m9.8 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current2 A | FuseUnfused return | Drop / allowance1.17% / 10% |
| C5 · Blue Sea 5026 ST Blade Fuse Block 2 + ↔ Auxiliary DC load + | One-way length2 m6.6 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current8 A | Fuse10 A | Drop / allowance1.87% / 3% |
| C6 · Blue Sea 5026 ST Blade Fuse Block 2 − ↔ Auxiliary DC load − | One-way length2 m6.6 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current8 A | FuseUnfused return | Drop / allowance1.87% / 3% |
| C7 · AGM starter bank + ↔ Orion XS 12/12-50A IN + | One-way length3 m10 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current50 A | Fuse60 A | Drop / allowance2.78% / 3% |
| C8 · AGM starter bank − ↔ Orion XS 12/12-50A IN − | One-way length3 m10 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current50 A | FuseUnfused return | Drop / allowance2.78% / 3% |
| C9 · Orion XS 12/12-50A OUT + ↔ House / auxiliary bank + | One-way length1 m3.3 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current50 A | Fuse60 A | Drop / allowance0.91% / 3% |
| C10 · Orion XS 12/12-50A OUT − ↔ House / auxiliary bank − | One-way length1 m3.3 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current50 A | FuseUnfused return | Drop / allowance0.91% / 3% |
Component table and exact example assumptions
| Component | Ratings, role and assumptions |
|---|---|
| House / auxiliary bankPlanning placeholder | 12 V · 200 Ah 12 V, 200 Ah planning placeholder. Select an actual bank, compatible BMS, charge/discharge limits and battery-end protection. Ah does not select the fuse. Planning example, not installation approval. Batteries, the PV array and unnamed loads are placeholders. Battery acceptance, BMS controls, low-temperature charging, short-circuit current and runtime have not been verified. Fuse ratings are preliminary cable protection or stated manufacturer choices. Exact fuse/holder, DC voltage, interrupt rating and battery-end placement still need verification. Cable fuses have no physical placement here; the editor retains its battery-protection warnings. Lengths are physical one-way conductor runs. Voltage drop includes a return; shared paths use the engine’s conservative current bounds, not a prediction of simultaneous power flow. The calculation does not verify unequal shared-return lengths as one complete circuit. AWG labels are approximate table counterparts to metric conductors, not identical cross-sectional areas. Sizing uses Crimp’s ABYC-based tables for 105°C copper outside engine spaces, with no additional heat or bundling derating in these examples. Explicit 3% circuit targets and 10% cabin-light allowances are planning choices; terminals on placeholders carry generic planning limits, not verified connector ratings. US RV, UK campervan and Australian 4WD wording does not establish UK or AS/NZS installation compliance. |
| Blue Sea 5026 ST Blade Fuse Block5026 | Blue Sea 5026: 12 ATO/ATC branches, 100 A maximum block total, 30 A maximum per branch, 32 V DC. Only two branches used. Input feed protection is separate; fuses are sold separately. Source: Blue Sea 5026 product page and wiring schematic, checked 2026-09-11. |
| Cabin lightsPlanning placeholder | 12 V · 2 A load allowance 2 A continuous planning allowance. No measured duty cycle or energy budget. |
| Auxiliary DC loadPlanning placeholder | 12 V · 8 A load allowance 8 A continuous placeholder; replace with the actual appliance and its startup requirements. |
| AGM starter bankPlanning placeholder | 12 V · 80 Ah 12 V AGM source placeholder. Engine cranking and alternator are outside this drawing. No vehicle input headroom, idle output or factory wiring has been verified. Dedicated logical return: use the vehicle’s designated ground point where required by battery current sensing. |
| Orion XS 12/12-50AOrion XS 12/12-50A | 50 A rated / planning output Non-isolated Orion XS 12/12-50A, rev 11 (06/2026). Logical IN− and OUT− represent its single physical GND terminal. Input/output limits are each up to 50 A; full output is not guaranteed at low input voltage. 60 A battery fuses and 16 mm² conductors are pinned choices. Remote/BMS control, charge profile, engine detection and alternator headroom require review. |
REDARC BCDC1240D 4WD setup
6 components · 10 conductors · 12 V house system
Solid red = positive · dashed dark = return. Shared routes show both styles. Cable IDs match the schedule. Only connected terminals are drawn; crossings are not junctions. Scroll the drawing sideways on a small screen. Read the assumptions before adapting it.
Protection is unfinished. The shown fuse ratings do not select an exact protective device or locate it at the battery. Battery-end placement and unspecified-fuse warnings remain in Crimp. All charging and load currents below are design allowances, not measured operating currents.
Both battery returns join at the modeled BATT− connection, representing the common black ground lead; PV− is unused. This is a logical connection, not a physical harness pinout. The engine’s generic input estimate does not verify REDARC’s voltage conversion or vehicle headroom.
Current engine findings
The blade-fuse interrupt check uses the engine’s chemistry-based fault-current assumption. This is not measured fault current. Resolve the bank and protection design before installation.
Check the exact fuse, holder and battery evidence →- critical: ATC fuse can't interrupt this battery's fault current (C3)
- critical: ATC fuse can't interrupt this battery's fault current (C5)
- warning: Fuse on House / auxiliary bank+ is too far from the battery (C1, C9)
- warning: Fuse on AGM starter bank+ is too far from the battery (C7)
- warning: House / auxiliary bank (LFP) has no fuse on the positive post (system)
- warning: 2 fused runs don't say which type of fuse (C1, C9)
Cable table — every displayed connection
Each length is one way. Drop is the engine’s run estimate including return, not a measured end-to-end system result; shared legs can have different conservative design-current bounds. “Pinned” marks a manufacturer-based example choice to review after edits. AWG is approximate; retain the stated conductor area when selecting actual wire.
| Circuit / endpoints | One-way length | Conductor | Design current | Fuse | Drop / allowance |
|---|---|---|---|---|---|
| C1 · House / auxiliary bank + ↔ Blue Sea 5026 ST Blade Fuse Block IN + | One-way length1 m3.3 ft | Conductor4 mm²AWG 11 · 45 A table | Design current10 A | Fuse15 A | Drop / allowance0.73% / 3% |
| C2 · House / auxiliary bank − ↔ Blue Sea 5026 ST Blade Fuse Block IN − | One-way length1 m3.3 ft | Conductor4 mm²AWG 11 · 45 A table | Design current10 A | FuseUnfused return | Drop / allowance0.73% / 3% |
| C3 · Blue Sea 5026 ST Blade Fuse Block 1 + ↔ Cabin lights + | One-way length3 m9.8 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current2 A | Fuse3 A | Drop / allowance1.17% / 10% |
| C4 · Blue Sea 5026 ST Blade Fuse Block 1 − ↔ Cabin lights − | One-way length3 m9.8 ft | Conductor1.5 mm²AWG 16 · 25 A table | Design current2 A | FuseUnfused return | Drop / allowance1.17% / 10% |
| C5 · Blue Sea 5026 ST Blade Fuse Block 2 + ↔ Auxiliary DC load + | One-way length2 m6.6 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current8 A | Fuse10 A | Drop / allowance1.87% / 3% |
| C6 · Blue Sea 5026 ST Blade Fuse Block 2 − ↔ Auxiliary DC load − | One-way length2 m6.6 ft | Conductor2.5 mm²AWG 13 · 35 A table | Design current8 A | FuseUnfused return | Drop / allowance1.87% / 3% |
| C7 · AGM starter bank + ↔ BCDC1240D Classic40 ALT + | One-way length3 m10 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current40 A | Fuse60 A | Drop / allowance2.22% / 3% |
| C8 · AGM starter bank − ↔ BCDC1240D Classic40 BATT − | One-way length3 m10 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current40 A | FuseUnfused return | Drop / allowance2.22% / 3% |
| C9 · BCDC1240D Classic40 BATT + ↔ House / auxiliary bank + | One-way length80 cm2.6 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current40 A | Fuse60 A | Drop / allowance0.58% / 3% |
| C10 · BCDC1240D Classic40 BATT − ↔ House / auxiliary bank − | One-way length80 cm2.6 ft | Conductor16 mm²AWG 6 · 120 A tablePinned choice | Design current40 A | FuseUnfused return | Drop / allowance0.58% / 3% |
Component table and exact example assumptions
| Component | Ratings, role and assumptions |
|---|---|
| House / auxiliary bankPlanning placeholder | 12 V · 200 Ah 12 V, 200 Ah planning placeholder. Select an actual bank, compatible BMS, charge/discharge limits and battery-end protection. Ah does not select the fuse. Planning example, not installation approval. Batteries, the PV array and unnamed loads are placeholders. Battery acceptance, BMS controls, low-temperature charging, short-circuit current and runtime have not been verified. Fuse ratings are preliminary cable protection or stated manufacturer choices. Exact fuse/holder, DC voltage, interrupt rating and battery-end placement still need verification. Cable fuses have no physical placement here; the editor retains its battery-protection warnings. Lengths are physical one-way conductor runs. Voltage drop includes a return; shared paths use the engine’s conservative current bounds, not a prediction of simultaneous power flow. The calculation does not verify unequal shared-return lengths as one complete circuit. AWG labels are approximate table counterparts to metric conductors, not identical cross-sectional areas. Sizing uses Crimp’s ABYC-based tables for 105°C copper outside engine spaces, with no additional heat or bundling derating in these examples. Explicit 3% circuit targets and 10% cabin-light allowances are planning choices; terminals on placeholders carry generic planning limits, not verified connector ratings. US RV, UK campervan and Australian 4WD wording does not establish UK or AS/NZS installation compliance. |
| Blue Sea 5026 ST Blade Fuse Block5026 | Blue Sea 5026: 12 ATO/ATC branches, 100 A maximum block total, 30 A maximum per branch, 32 V DC. Only two branches used. Input feed protection is separate; fuses are sold separately. Source: Blue Sea 5026 product page and wiring schematic, checked 2026-09-11. |
| Cabin lightsPlanning placeholder | 12 V · 2 A load allowance 2 A continuous planning allowance. No measured duty cycle or energy budget. |
| Auxiliary DC loadPlanning placeholder | 12 V · 8 A load allowance 8 A continuous placeholder; replace with the actual appliance and its startup requirements. |
| AGM starter bankPlanning placeholder | 12 V · 80 Ah 12 V AGM source placeholder. Engine cranking and alternator are outside this drawing. No vehicle input headroom, idle output or factory wiring has been verified. Dedicated logical return: use the vehicle’s designated ground point where required by battery current sensing. |
| BCDC1240D Classic40BCDC1240D | 40 A rated / planning output BCDC1240D / Classic40 only, INST173-3 EN. Red vehicle input, brown auxiliary output, shared black negative. Solar, blue trigger and orange profile wires are not drawn. 60 A battery fuses and 16 mm² conductors are pinned example choices, with 0.8 m auxiliary run. Generic input estimate does not model conversion efficiency, solar sharing or vehicle headroom. PV-negative is unused; the banks share a common return. |
Before adapting an example
What these drawings assume
The vehicle examples represent a fixed auxiliary bank with a logical common return. Follow the vehicle manufacturer’s designated ground point, especially around starter-battery current sensors. For a boat, use the distinct starter/house example on the boat page. A removable canopy, camper trailer or caravan needs its own connector, return path, longer-run sizing and protection design; these are not towing layouts or factory vehicle schematics.
- Planning example, not installation approval. Batteries, the PV array and unnamed loads are placeholders. Battery acceptance, BMS controls, low-temperature charging, short-circuit current and runtime have not been verified.
- Fuse ratings are preliminary cable protection or stated manufacturer choices. Exact fuse/holder, DC voltage, interrupt rating and battery-end placement still need verification. Cable fuses have no physical placement here; the editor retains its battery-protection warnings.
- Lengths are physical one-way conductor runs. Voltage drop includes a return; shared paths use the engine’s conservative current bounds, not a prediction of simultaneous power flow. The calculation does not verify unequal shared-return lengths as one complete circuit. AWG labels are approximate table counterparts to metric conductors, not identical cross-sectional areas.
- Sizing uses Crimp’s ABYC-based tables for 105°C copper outside engine spaces, with no additional heat or bundling derating in these examples. Explicit 3% circuit targets and 10% cabin-light allowances are planning choices; terminals on placeholders carry generic planning limits, not verified connector ratings. US RV, UK campervan and Australian 4WD wording does not establish UK or AS/NZS installation compliance.
Adding monitoring or larger distribution changes the current paths. Read the SmartShunt return-path example and Lynx Distributor example, including their conservative series-current bounds and unresolved protection. The model pages keep those limitations visible.
Manufacturer evidence
Exact models and manuals
Checked 11 September 2026. Component notes identify the source-backed ratings and the choices made for this example.
Victron EnergyOrion XS 12/12-50A installation and cable/fuse tableRev. 11 — 06/2026, §3.3 and charger-mode connections; checked 11 September 2026. Single physical GND and external battery protection.Victron EnergyOrion XS 12/12-50A exact-model technical dataThe 50 A model’s input and output setting limits. These do not establish available vehicle power.Blue Sea SystemsBlue Sea 5026 product specifications and wiring schematic5026 with negative bus: 100 A block total, 30 A per branch, 32 V DC; fuses sold separately. Product page and linked schematic checked 11 September 2026; no revision stated.REDARCBCDC Classic Dual Input manualINST173-3 EN, BCDC1240D column, pp. 6 and 12–18. 60 A input/output fuses, minimum cable area and short auxiliary run; checked 11 September 2026.REDARCBCDC common-ground and detachable-battery wiringVehicle current sensing may require a chassis return. The separate detachable-battery illustration explains why a towing installation needs another layout.