What Size Victron Shunt Do I Need? 300A vs 500A vs 1000A

What size Victron shunt you need depends on the highest current that will flow in or out of your battery. Victron sells the SmartShunt in IP21 and IP65 versions in 300A, 500A, 1000A and 2000A. Pick a shunt rated above your biggest continuous current, usually set by your inverter, and you’re done.

Mobile Solar Consulting: which Victron shunt is best for you.

What Size Victron Shunt: Step by Step

Find your largest load. In most systems it’s the inverter.
Convert watts to battery amps: inverter watts ÷ battery voltage ÷ efficiency. A 2,400W inverter on 12V at 90% efficiency pulls roughly 2,400 ÷ 12 ÷ 0.9 ≈ 222A. Estimate.
Add simultaneous DC loads that don’t go through the inverter.
Check charging current. Chargers flow through the shunt too, but they’re usually lower than the inverter draw.
Choose the next size up.

Example Systems (Estimates)

System	Biggest current (est.)	Shunt size
12V van, Phoenix 12/800 + DC loads	about 80–100A	300A
12V RV, MultiPlus-II 12/3000	about 220A+	500A
12V RV, MultiPlus-II 12/4k	about 315A+	500A
24V or 48V cabin, two inverters	depends on total	1000A, or a Lynx Shunt

All currents are our estimates from inverter watts ÷ battery voltage ÷ 0.9.

Accuracy Doesn’t Change Much

Victron’s datasheet lists current resolution of ±0.01A and current-measurement accuracy of ±0.4%, so a bigger shunt won’t make small readings useless. The 500A is the most common pick in the van and RV videos we analyzed.

SmartShunt vs Lynx Shunt

If you already use Victron’s Lynx busbar system, Victron also makes a Lynx Shunt VE.Can module that combines battery monitoring with the main fuse.

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Buy: Victron SmartShunt 500A on Amazon, SmartShunt IP65 500A on Amazon

Want the source figures? The SmartShunt page on Victron’s site has the datasheet.

Worked Example: Sizing for a 24V and a 48V System

Higher battery voltage means less current for the same inverter, which often lets you use a smaller shunt.

Inverter	12V current (est.)	24V current (est.)	48V current (est.)
1,200W	≈ 111A	≈ 56A	≈ 28A
3,000W	≈ 278A	≈ 139A	≈ 69A
5,000W	≈ 463A	≈ 231A	≈ 116A
8,000W	≈ 741A	≈ 370A	≈ 185A

Estimates: watts ÷ voltage ÷ 0.9 efficiency. A 3,000W inverter needs a 300A shunt on 12V only if there’s nothing else drawing at the same time, so a 500A gives sensible headroom. The same inverter on 24V fits comfortably on a 300A.

Worked Example: A Typical Van Build

A 12V van with a 2,000W inverter, a 30A DC-DC charger, a 30A solar controller and about 20A of DC loads (fridge, fan, lights):

Discharge peak: inverter ≈ 185A (2,000 ÷ 12 ÷ 0.9) plus 20A of DC loads ≈ 205A.
Charge peak: DC-DC 30A + solar 30A ≈ 60A, or more if a shore charger runs too.

The biggest number is about 205A, so a 300A shunt covers it. Many builders still choose the 500A for room to grow, such as a larger inverter later. Estimates.

Worked Example: A Home Backup Bank on 48V

A 48V bank feeding two 5,000W inverters in parallel draws roughly 231A combined (10,000 ÷ 48 ÷ 0.9, estimate). A 500A SmartShunt works; a Lynx Shunt VE.Can is the alternative if you’re building around Lynx busbars and want the main fuse in the same unit.

Don’t Forget Surge

Inverters can briefly draw much more than their continuous rating when a motor or compressor starts. Those surges last seconds and a SmartShunt measures through them; the rating that matters for choosing is the continuous current. Your fuse and cables are what must handle the surge, so size them from the inverter’s manual.

What the SmartShunt Measures

Battery voltage, current and power
State of charge and time remaining, from the Ah counted in and out
History such as deepest discharge, number of cycles and total Ah drawn
An auxiliary input you can use for a starter battery voltage, midpoint voltage on a bank, or a temperature sensor

All of that shows in VictronConnect over Bluetooth, and on a GX device and VRM through the VE.Direct port.

Installation Steps

Turn off all loads and chargers and disconnect the battery negative.
Mount the shunt close to the battery and connect the battery negative to the shunt’s battery side.
Move every other negative connection (inverter, chargers, DC loads) to the shunt’s system side. Nothing except the shunt should connect to the battery negative.
Connect the small red power wire, with its inline fuse, to the battery positive.
Open VictronConnect, enter the battery capacity in Ah and the charged voltage, and let the battery reach full charge once so the state of charge synchronises.

Lithium vs Lead-Acid Settings

For lithium, set Peukert exponent close to 1.05 and charge efficiency near 99%, per common Victron guidance for LiFePO4. Lead-acid batteries use the defaults (Peukert 1.25, charge efficiency 95%). The charged-voltage setting should sit a little below your charger’s absorption voltage so the shunt recognises when the battery is full.

FAQ

Can I use a 500A shunt on a small system?

Yes. It works fine on small systems, and it leaves headroom for later.

IP21 or IP65?

IP65 versions are dust-tight and water-resistant for wet or exposed locations; IP21 suits dry interiors.

Does the shunt size limit my inverter?

The shunt’s rating is a measurement limit. Cables and fuses must still be sized for your current.

Do I need a bigger shunt if I add solar?

Usually not. Solar charge current is normally far below inverter draw. Add up the largest charge and discharge currents and size for whichever is higher.

Can one shunt monitor two battery banks?

It measures the current of one bank. The auxiliary input can show the voltage of a second battery, such as the starter battery, but not its state of charge.

Where should the shunt go?

On the negative side, between the battery and everything else, as close to the battery as practical.

Sources: Victron SmartShunt product page and SmartShunt datasheet (victronenergy.com); Mobile Solar Consulting, “Which Victron Shunt is BEST For You??”.