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Diagnostics reference

Every check Crimp runs on a 12 V drawing

Crimp runs 83 checks on your drawing: wiring faults, cable and fuse sizing, charging compatibility, battery banks and energy use. Here is how to read the findings, what still needs verification, and the complete list of checks.

Checked Oct 8, 2026 · 12 V DC planning · your manual wins

Two makers review a plan beside enclosed electrical equipment, a multimeter and a cable coil.

From a finding to a decision

Read, correct, then check again.

Open a finding to read its explanation and focus on the affected parts of the drawing. Start with critical issues, then work through warnings and notes.

  1. Draw and enter the facts

    Connect the components and enter cable lengths and equipment data. Missing or estimated inputs need review too.

  2. Locate and understand

    Open the finding. Read what triggered it, which parts it affects and what the suggested change would do.

  3. Update and recheck

    Apply an offered fix when appropriate, or edit the drawing. Confirm equipment details in the manual where the model cannot verify them.

The review loop: a modeled fault can clear after a correction; verification notes can still require evidence from outside the drawing.

Reading the findings

Critical
Don't build this as drawn
Warning
Resolve or verify before installation
Note
Confirm the information or equipment detail the note calls out

Before you rely on a result

What the drawing cannot establish.

The checks depend on the connections and values you enter. Review unverified inputs and the exact equipment manuals before using a result to choose parts.

The physical installation
Cable routing, temperature, conduit, workmanship and the exact equipment limits still need review. The drawing cannot inspect the installation or establish compliance with your local requirements.
Fault current and fuse evidence
Conductor impedance is not modeled. Installed fuse interrupt ratings and coordination between fuses in series need product evidence; a fuse family name alone does not establish that protection.
AC behavior inside equipment
AC checks cover drawn grounding paths and selected earth-leakage protection arrangements. They do not verify internal bonding relays, transfer modes or breaker operation. AC sizing uses the inlet rating.
BMS controls and unverified inputs
BMS control wiring and disconnect ratings need manufacturer verification. Confirm estimated component data, selected parts and relevant cable lengths; a provisional result remains dependent on those inputs.

The complete reference

Find a check by topic.

All 83 checks are listed below. The severity shown is the most serious level each check can raise; your drawing determines which findings appear.

21 checks

Fuses and protection

Whether conductors have suitable fuse protection, manufacturer limits are met, and supported solar inputs have a drawn disconnection path.

  • Warning

    A supported solar controller cannot be disconnected from its array

    An array conductor still reaches the controller after the reviewed PV disconnect paths are opened. The supported controller's manual requires PV disconnection; bypasses and the required poles must be checked.

  • Critical

    A positive run with no fuse anywhere on the path

    A short on this cable melts it before anything trips. Every positive conductor leaving a battery needs a fuse; ABYC E-11 exempts only the engine cranking conductor.

  • Critical

    A charging source's positive output reaches the battery unfused

    The output cable of an alternator, a solar controller or a charger is a battery conductor too. A chafe anywhere on it dumps the bank's full short-circuit current with nothing to stop it.

  • Critical

    A charger's positive output reaches the battery unfused

    Same fault as above, called out separately because the charger's manual usually shows the fuse and the drawing forgot it. ABYC E-11 wants the fuse within 7 in of the battery.

  • Critical

    The feed cable into a fuse block is itself unfused

    The slot fuses protect each branch, not the trunk that feeds them. If that trunk chafes on the way to the block, nothing opens.

  • Critical

    A fuse-block slot is carrying a load with no rating picked

    Until a rating is chosen the slot is a straight connection. The branch cable behind it can melt before anything trips.

  • Warning

    A lithium battery has no fuse on its positive post

    A lithium bank can deliver five to ten thousand amps into a short. With the first fuse further than 175 mm from the post, that conductor carries all of it until something else gives way.

  • Warning

    The first fuse sits too far from the battery

    ABYC E-11 wants the fuse within 175 mm along the conductor from the positive post. Everything before the fuse is unprotected cable.

  • Critical

    A fuse rated above what its wire can carry

    The fuse lets that current flow indefinitely, but the conductor's continuous ampacity is lower. The insulation cooks before the fuse opens. Fit a smaller fuse or a fatter wire.

  • Critical

    A branch is relying on the battery's main fuse to protect a thin wire

    The terminal fuse is sized for the bank's worst-case fault, not for a 25 A branch. That branch needs its own fuse near the load, not a fatter wire to suit a 300 A MRBF.

  • Warning

    A fuse rating below the modeled demand on its run

    A sustained load above the installed rating needs review. Brief starting loads and provisional current estimates require the installed fuse's time-current data, rather than a definite trip prediction or an automatic replacement.

  • Warning

    Fuse interruption and coordination need product evidence

    One bank-level warning identifies missing fault-current data, installed fuse ratings and maximum DC voltage. Family reference values cannot verify an installed fuse, and an upstream fuse alone cannot establish a tested series combination.

  • Warning

    Cable and device declarations disagree about a fuse

    A cable rating differs from its attached holder or battery-post fuse. Confirm the physical fuse locations and ratings before treating these declarations as the same device or as separate protection.

  • Warning

    A fuse rating outside the selected family's supported range

    Compares the declared rating with the selected family's reference current range. Exact product availability, voltage rating, interrupt capacity and coordination still require verification; a family name alone does not establish a suitable protective device.

  • Critical

    Lynx branch fuses add up to more than the module allows

    Victron limits the total of the circuit fuses on a Lynx chain to the lowest-rated module in it. Above that, the bus bar itself is the weak point.

  • Warning

    Windlass protection differs from its specified breaker rating

    The declared supply protection does not include the exact supported windlass model’s manufacturer breaker rating on every modeled path. Feeder protection and the equipment breaker can serve different purposes.

  • Warning

    A CRX supply fuse below the documented rating

    Exact catalog CRX-50/65 models specify 15 A at 12 V or 7.5 A at 24 V. Lower declared positive-path ratings need review. Automatic advice applies only to dedicated positive leads; this check does not establish a universal maximum across variants, exact fuse identity or interrupt capacity.

  • Warning

    A fuse outside the manufacturer's permitted range

    The battery-side fuse must protect the connected equipment as well as the conductor. Increasing the wire size does not permit a fuse above the model's documented maximum.

  • Warning

    An upstream fuse exceeds the supplied lead's documented rating

    A manufacturer-supplied conductor has its own documented ampacity. A larger extension cable does not increase that rating. Protect the supplied lead at its source; this check does not claim a terminal-contact or total-panel rating.

  • Warning

    A fuse rated above the switch or terminal it feeds

    ABYC E-11.10.1.1 wants the fuse to protect the equipment as well as the wire. A 400 A fuse ahead of a 15 A switch leaves the contact carrying anything under 400 A with nothing to trip — the wire was sized to host the fuse, the device was not.

  • Critical

    A solar string fuse above a panel’s maximum series-fuse rating

    Compares each individual string fuse with the explicit manufacturer limit of its series modules. A shared combiner trunk is checked separately from string protection. Panels without a declared limit are not assigned an assumed maximum.

10 checks

Wire, terminals and voltage drop

Whether each run and the stud it lands on can carry the current for as long as it flows, and whether the load at the end still sees enough volts.

  • Warning

    Starting cable voltage drop needs verification

    The drawn starter loop exceeds the planner's conservative starting voltage-drop target, even with its calculated or pinned cables. Verify starting-current data and the fitted engine's installation requirements before relying on the sizing.

  • Warning

    Incomplete current calculations require verification

    A complete signed calculation is unavailable for these current paths or component definitions. Estimates from fuse or terminal ratings and missing active-device data remain provisional; verify component roles, actual loads, current sharing and wire sizes.

  • Warning

    Branch-current bounds depend on source selection or sharing

    Sizing keeps conservative current bounds across possible source routes. One grouped warning identifies branches whose actual current allocation needs verification before concluding that a wire, terminal or fuse is overloaded.

  • Warning

    A cable below the manufacturer's installation minimum

    A manually selected power lead is smaller than the model's documented minimum. Generic ampacity and voltage drop alone do not satisfy that installation requirement.

  • Warning

    A wire too thin for the continuous current on it

    ABYC E-11 wants conductor ampacity above the continuous load with headroom. This run falls short, and without a fuse at or below its ampacity the conductor can overheat before anything trips.

  • Warning

    Too much voltage lost between the battery and a load

    Each cable on its own may pass, but the whole path from battery to load adds up. The threshold is that circuit's own ABYC E-11 allowance, 3 % on critical circuits and 10 % on general lighting, not one fixed number.

  • Warning

    Too much voltage lost between the solar array and controller

    Supported solar strings include all feed, return and series conductors, with shared trunks carrying the combined current. Their complete-loop loss is compared with the selected planning target and stricter cable overrides; this target is not a universal PV standard.

  • Warning

    Charging-source loop exceeds its voltage-drop target

    The complete positive and return path is checked together at the design current. Supported exact models use their documented manufacturer allowance; other chargers and direct DC sources use the chosen sizing target. Manual wire sizes remain unchanged, and uncertain current routing remains conditional.

  • Critical

    A cable carrying more than the stud it lands on is rated for

    The conductor was sized for the current; the switch contact or bus stud was not. It heats at the lug and can fail long before any fuse notices.

  • Note

    Two cables between the same parts with very different lengths

    Cables between the same pair of components normally share a route, so a big difference is usually a typo. The longer length is the one voltage drop should be judged on.

11 checks

Charging sources

Whether the alternator, the DC-DC, the shore charger and the solar controller are matched to each other and to the bank they feed.

  • Critical

    A DC-DC charger pulling more than the alternator can supply

    Above half the alternator's continuous rating it runs hot at idle; past three quarters it will eventually cook. Only chargers whose input actually reaches the alternator are counted.

  • Critical

    A DC-DC charger fed straight from the alternator with no battery on that bus

    Nothing clamps the charger's input and nothing absorbs the alternator's load-dump transient. The first start without the start battery online takes out the regulator or the charger.

  • Warning

    Charging capacity exceeds the battery charge threshold

    Compares sources with paired battery paths against declared thresholds, manufacturer recommendations, catalog planning thresholds or chemistry estimates. The notice identifies the basis; verify battery/BMS limits and simultaneous charger settings. Rated capacity is not measured charging current.

  • Critical

    An inverter that can draw more than the bank can deliver

    The inverter's full-load current is above the bank's continuous discharge limit. Expect voltage sag under load and a BMS that cuts out mid-cycle.

  • Warning

    A connected solar input without a complete array circuit

    Checks both PV conductors and series paths at each intended input. Unused optional inputs stay quiet, including a shared battery negative. Switch positions and sunlight do not change this physical wiring check.

  • Critical

    A solar string whose cold-morning open-circuit voltage exceeds the controller's limit

    Panel voltage rises as temperature falls. The longest string is checked at −25 °C using the NEC 690.7 correction; above the controller's maximum PV input, the first cold sunrise fries it.

  • Warning

    A charger fed from the engine's starter terminal instead of the alternator output

    That cable is sized for cranking surge and won't show alternator current when the engine runs. Charging devices belong on the alternator's B+ output.

  • Critical

    A DC-DC charger's output landed on the same bus its input draws from

    As drawn, the charger is trying to top up the battery that powers it. Its output belongs on the separate house bank.

  • Critical

    A charger's input and output both reach the same battery

    The charger would be charging the bank whose current feeds it. It refuses to run, or cycles losses through itself. The output belongs on a different battery.

  • Warning

    A source has no complete return to its battery bank

    A source's positive connection does not establish a charging circuit. Verify its negative or case-ground path back to the same bank, including explicitly declared internal connections.

  • Warning

    A charger whose negative never reaches the battery

    The positive is wired but the return isn't, or lands on something that goes nowhere. Without a path back the charger can't deliver a single amp.

17 checks

Wiring mistakes

The drawing errors that would be a dead short, a shock hazard or a device that never turns on.

  • Warning

    A documented floating-neutral source feeds an earth-leakage panel

    A supported source has a floating neutral in its factory configuration, and no source-side neutral/PE bond is drawn for the supported earth-leakage panel. Verify the installation-specific arrangement; do not add a bond by assumption.

  • Critical

    A conductor path shorts a battery or cell

    Positive and negative on the same battery are joined by the drawn conductors, including shared monitor terminals. Separate sensing inputs must stay separate; a fuse does not make a direct short safe.

  • Critical

    A positive terminal wired straight to a negative

    Energising it is a dead short. Cables vaporise before any fuse can react.

  • Critical

    An AC line or neutral connected to a DC rail

    Traces AC-to-DC paths through cables, shared posts and internal ties, including fuses. These connections can cause shock or fire; verify custom terminals against the manual. Protective-earth paths belong to separate grounding checks, and converter power stages are not copper bonds.

  • Critical

    A device rated for one voltage sitting on a rail of another

    A 12 V device on a 48 V rail is destroyed instantly; a 48 V device on 12 V never starts. It needs a converter on the correct rail.

  • Critical

    Two different voltage rails bonded together with no converter

    Everything on the lower-voltage side sees the higher voltage the moment the system is switched on.

  • Warning

    A protective-earth or chassis terminal has no continuous grounding path

    The drawn ground conductor does not reach a modeled grounding reference, such as battery-bank negative or a supported shore protective-earth terminal. A floating ground island or a wire ending on another case does not establish a fault-current path.

  • Warning

    A load with no path to either battery terminal

    It is on the drawing but not in the circuit, so it won't power on and nothing has been sized for it.

  • Warning

    A load whose negative is wired but whose positive never reaches a battery

    Half a circuit. The load stays dark until the positive side is closed. When the branch is confirmed to have no source, sharing a negative connection does not add its rated current to a working circuit.

  • Warning

    A load whose positive is wired but whose negative never gets back

    The other half. Current has nowhere to return, so the load stays dark.

  • Warning

    A load fed through a converter that isn't itself wired to a battery

    The load is connected correctly to the converter, but the converter has no supply yet, so neither does the load.

  • Critical

    A voltage-sense lead being used as a bus

    A monitor's sense terminal only measures. Two cables on it, or two battery positives joined only through it, means real current through a wire rated for one amp, unfused and unsized.

  • Warning

    Verify the battery monitor’s power and fused lead

    Supported SmartShunts require a complete Vbatt+ supply and paired negative return. Missing or unverified lead protection needs attention; the optional AUX input cannot supply the monitor. Fuse identity, supply voltage and installation still need verification.

  • Warning

    A return bypasses the battery monitor's shunt

    A load or charger returns to the monitored battery without crossing its shunt, so the monitor misses current and can report an incorrect state of charge. This check assumes whole-bank monitoring; it does not model a shunt configured as a separate DC energy meter.

  • Warning

    A cable marked as a series link between things that aren't like cells

    Series jumpers make sense between batteries or between solar panels. Anywhere else, positive to negative is still a short.

  • Warning

    More than one cable between the same two terminals

    Almost always left over from editing. The duplicates carry no extra current and clutter the schedule.

  • Critical

    A cable ending on a terminal the part doesn't have

    Usually from a part that was swapped or a file that was edited by hand. It is drawn but connects nothing, so whatever it feeds is missing from every number.

9 checks

Battery banks

Whether batteries form a compatible bank and supported models have the external BMS protection they require, without a bypass around its disconnect.

  • Critical

    A supported battery has no connected external BMS

    Selected Victron Smart and NG batteries require an external BMS. No compatible controller is connected to the battery supply in the drawing. Internal-BMS and unknown batteries are not assumed to need a separate controller.

  • Critical

    A connected BMS excludes this battery family

    The controller's declared compatibility excludes a connected battery model. Similar voltage or current ratings do not make Smart and NG controllers interchangeable.

  • Critical

    A conductor bypasses the BMS disconnect

    A drawn conductor path joins the battery and system posts around a supported BMS. Its built-in disconnect cannot interrupt that bypass.

  • Critical

    Connected demand exceeds declared battery discharge ratings

    Adds known sustained demand on complete battery circuits. Parallel ratings form an aggregate bound; series levels retain their limits. Optional charging is not subtracted. Missing current, incomplete routes and unspecified ratings remain unverified; verify the actual battery and BMS ratings.

  • Warning

    Parallel batteries with unequal cable lengths

    When the interconnects differ by more than 20 %, the battery on the shorter run hogs the charge and the discharge. It ages first and the bank's capacity follows it down.

  • Warning

    Lithium and lead-acid batteries in parallel

    They rest at different voltages and follow different curves, so one dumps current into the other whenever the system is idle. The lead bank wears out fast and the lithium cells see charge profiles they weren't designed for.

  • Warning

    Series-stacked batteries with different voltages

    The smaller cell discharges into the larger one every cycle, sags below its floor and eventually reverses. Series strings need matched cells.

  • Warning

    A battery rail above the 60 V DC touch-safe limit

    Ordinary tinned marine cable and most distribution blocks are not rated for hot-touch above 60 V. If the stack was meant to be that tall it needs special insulation and lockout; if it wasn't, drop some cells.

  • Note

    A battery with no chemistry set

    Its fault current and charge acceptance are unknown, which is not the same as zero. The interrupt-capacity and acceptance checks skip this bank until a chemistry is chosen.

3 checks

Energy budget

Whether the bank lasts the day on what the loads draw and the sources put back.

  • Note

    No battery in the system yet

    Without one there is no runtime, autonomy or charging time to estimate.

  • Note

    Battery capacity is missing

    Battery symbols are present, but their definitions do not establish usable capacity. Enter the batteries' nominal amp-hours before relying on runtime, autonomy or charging-time estimates.

  • Warning

    Loads with nothing putting energy back

    The budget shows what the loads take per day and how many days the bank lasts with no source at all.

12 checks

Things left to confirm

Specifications, control wiring and protection details the drawing cannot establish, including BMS shutdown controls, service isolation and internal AC bonding.

  • Warning

    BMS sensing and shutdown controls need verification

    Power connections do not verify the battery data chain, charge/load controls or compatible disconnect equipment. One grouped warning identifies external BMS installations whose complete protection chain still needs manufacturer verification.

  • Note

    Solar array disconnection needs verification

    The drawing cannot establish a suitable means of disconnecting the PV conductors. Unknown switch capabilities, ratings and manufacturer requirements need verification; a fuse or remote control does not establish service isolation.

  • Note

    Inverter DC disconnection needs verification

    The inverter cannot be shown disconnected from every DC supply by reviewed switch paths. Confirm the service procedure in its manual; a shared upstream disconnect may suffice, and an external switch is not universally mandatory.

  • Warning

    AC neutral bonding and earth-leakage protection need verification

    The source paths, internal neutral/PE bonds or transfer relays for a supported earth-leakage panel are unresolved. Verify every supply mode, grounding path and protective device against the manuals.

  • Warning

    Charging through a battery isolator needs separate verification

    The isolator's battery outputs stay separate. Charging through the one-way device is not modeled: affected cable sizes are provisional and its charging contribution is excluded from the energy budget. Verify the complete installation against manufacturer instructions.

  • Warning

    A connected consumer has no operating-current specification

    Loads and powered monitor inputs with missing operating current leave their branches and shared feeders unverified. Wire, fuse, consumption and runtime calculations remain incomplete; terminal and fuse ratings cannot substitute for verified operating current.

  • Warning

    Verify the manufacturer-specified circuit breaker

    Exact supported windlass models specify a circuit breaker, not merely an ampere rating. Confirm its identity and trip curve; a generic fuse with the same rating does not establish equivalent protection.

  • Warning

    Verify the CRX manufacturer wire chart

    CRX-50/65 wire sizing needs verification for modified identity, unresolved full feed/return paths, unknown voltage, 24 V, or 12 V runs beyond 8 m. Supported 12 V sizing uses the longer full leg, including shared trunks. Modified identities inherit no numerical manufacturer rules.

  • Warning

    A custom part whose declared currents can't describe a real device

    A surge below the continuous draw, or an engine whose surge is so far above its draw that the two look swapped. These numbers feed every sizing decision, so they are checked before anything is sized from them.

  • Note

    Parts whose specs were recalled by the assistant, not read off a datasheet

    Everything downstream is computed from those figures, so a wrong nameplate number gives a wrong answer that still looks checked. One note lists them all.

  • Note

    Parts the assistant picked because you didn't name one

    The specs are the catalog's, but they describe the part it chose, which may not be the one you're buying. Swap in yours and the note clears itself.

  • Note

    Guessed run lengths that actually decide a wire size

    Only the runs where the length picked the gauge are listed. A short bus jumper's guess can't change a number, so it isn't in the way.

Where the rules come from

Check the basis for the numbers.

Sized against ABYC E-11. Boats built to EU rules answer to ISO 13297 — check these figures against it before you build.

Victron EnergyWiring Unlimited: DC wiringThe plain-language reasoning behind fusing every battery conductor, keeping parallel interconnects equal, and why a DC-DC belongs behind a battery.Blue Sea SystemsSelect a fuse and fuse holder for your DC product installationWhere the 7 in rule comes from in practice, and how a fuse's interrupt rating is matched to the battery that feeds it.LittelfuseFuseology selection guideInterrupt ratings and the ampere ranges each fuse family is made in, which is what the interrupt and availability checks are built on.American Boat & Yacht CouncilStandards Update, Supplement 65ABYC's own notice of the current E-11 revision. The standard itself is sold, not published, so this is the public pointer to the edition the checks follow.Victron EnergyLithium Battery Smart: system design and BMS selectionCompatible external BMS models, the battery data chain, and the controls that shut down loads and chargers.Victron EnergyLithium NG: system design and BMS selectionThe separate NG controller family and its required battery sensing and shutdown connections.Victron EnergySmartSolar MPPT 75/10–100/20: installationSection 4.3 requires a means of disconnecting the current-carrying PV conductors; a drawn fuse alone does not establish that arrangement.Victron EnergyMultiPlus-II: operation and shutdownThe shutdown procedure includes DC disconnection; installation disconnect requirements still depend on the exact model and manual.Victron EnergyMultiPlus-II: installation and groundingSection 4.4 describes uninterrupted casing grounding and the mode-dependent neutral-to-chassis relay.HondaEU2200i owner's manualPrinted page 54 documents the generator's floating factory neutral; its use with earth-leakage protection needs installation-specific review.Blue Sea Systems8100 ELCI Main 30A Double PoleIdentifies the leakage-protection panel covered by the source-bonding checks. A generic panel name is not evidence that an RCD is fitted.
Keep goingSee how the numbers are madeWhich ampacity table, which voltage-drop allowance and which fuse ladder the wire and fuse sizing follows, and the limits of each.Keep goingReview your own drawingAdd your components, connections and cable lengths, then open the findings to work through the checks that apply.

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