The premise
The Victron Lynx Shunt is around €300. The Smart Shunt does the same measurement job for around €80. Robbert has read enough comments to know the Lynx unit gives plenty of people grief, while the Smart Shunt is reliable. He wants the Lynx form factor for his three-phase Victron build, but not the Lynx price. So he builds his own.
The result is a 3D-printed Lynx-sized housing with a Smart Shunt inside, optionally combined with a 500 A battery switch and a precharge button. Total saving lands around €200 on the shunt alone, with features the original does not offer.
Two build options
Option 1: passthrough busbar. A solid copper busbar runs across the top of the housing carrying the full battery current. The Smart Shunt sits underneath. This is the simplest version, designed for setups with heavy loads (Robbert's three 5 kVA Multiplus units fit here).
Option 2: switch and shunt. The Smart Shunt sits below, a 500 A battery switch sits above. Battery current enters one switch terminal and leaves through the other, then heads to the distributor. There's no top busbar in this version, which makes it best for smaller packs where the current stays modest.
Option 2 unlocks the soft-start trick (more on that below). Option 1 can additionally accept a Class T fuse as a bridge in the top busbar slot, using an extra 3D-printed insert that keeps everything at the right height.
Parts and costs
| Part | Cost |
|---|---|
| Victron Smart Shunt | €89 |
| 3D-printed housing parts | around €3 in plastic |
| Copper bar, 30 × 8 mm, 15 cm long | €28 |
| Class T fuse (optional) | €50 |
| 500 A battery switch (optional) | €10 to €30 |
| Cell connectors | around €10 |
Build costs depending on configuration:
- Passthrough busbar, no fuse: around €148. Saves €197 vs original.
- Passthrough busbar, with Class T fuse: around €198. Saves €147 and adds a proper main fuse.
- Switch and shunt option: around €150. Saves €195 and adds a battery disconnect plus the option to wire a soft-start bypass.
The soft-start bypass
This is the feature the Lynx Shunt does not have at any price.
When the Multiplus is first connected to a fully-charged battery, the inverter's input capacitors are empty. A large pulse of current rushes from the battery into the caps the instant the switch closes. The pulse is hard on the capacitors and can stress the BMS. It also burns the contact surface of the main switch over time, increasing resistance.
The bypass solves it with a momentary push-button and a 24 V lamp wired across the main switch.
- The main switch is open. Battery and load are isolated.
- Press and hold the bypass button. Current flows from the battery through the lamp, which acts as a resistor, slowly charging the Multiplus capacitors.
- The lamp glows brightly at first, then fades. When the lamp is out, the capacitors are full.
- Close the main switch. No spark, no contact damage.
This works only on the switch-and-shunt build because the lamp needs to bridge an actual switch. The passthrough busbar version cannot do it; on that one you'd need to hold a lamp in line by hand before connecting cables.
Building it
Robbert uses a 3D-printed Lynx-style housing, originally Victron RAL 7012 grey. His own prints are RAL 7015 (close but not identical; he later paints them with Crop RAL 7012 spray to match the real Lynx Power In).
For the switch option, he uses a 500 A battery switch. The factory mounting feet get cut off at 20 mm so the switch sits flat against the three raised mounting bosses inside the lid. Three screws hold it in place. The Smart Shunt mounts directly underneath. It's a tight fit but it goes.
The copper busbars are cut from 30 × 8 mm copper flat bar. For the passthrough version, one full-length bar runs across the top. For the switch version, two shorter pieces connect the unit's terminals to the switch. The full length of the original Lynx Power In has a hanging point that gets in the way of the busbar on the switch build, so an alternative 3D model without that mount is provided.
Where the Class T fuse goes, an additional 3D insert raises the fuse terminals to match the distributor's connection height. The fuse becomes a removable bridge in the top busbar path.
Finishing touches
The Lynx Power In has two protruding busbar pins on its left side, which look unfinished. Robbert adds a small printed cover that snaps onto them. It seals the open ends and gives a little extra mounting space for accessories.
For the labels: when the housing is mounted upside-down (cables exiting upward), a sticker from the Lynx Power In packaging can be used to keep the markings readable on top of the busbar.
Where this fits
If you're already paying Victron prices for the Multiplus units, the Lynx accessories add up fast. Replacing the Lynx Shunt with a Smart Shunt in a Lynx-shaped housing keeps the visual consistency and the Cerbo integration, but cuts about €200 off the cost. Adding the switch-and-precharge variant on top of that gives you the kind of battery isolation and soft-start the off-the-shelf parts only sort of cover.
Takeaways
- The Smart Shunt does the same metering job as the Lynx Shunt for roughly a quarter of the price.
- A 3D-printed Lynx-style housing keeps the Victron aesthetic and the Cerbo integration.
- The passthrough busbar version handles heavy current; the switch version is for smaller setups.
- The precharge bypass is a feature the original Lynx Shunt does not offer at any price.
- Total saving lands around €195 to €200 per shunt, depending on options.
