What Is a Battery Inverter Cable Size?
As an Amazon Associate we earn from qualifying purchases.
A battery inverter cable size is the cross-sectional area of the cable that connects an inverter’s DC terminals to its battery bank, usually written in square millimetres (mm²). For the Victron Inverter Smart models, the Victron installation page gives a recommended cable cross-section for each model, split by cable run: 0 to 5 metres and 5 to 10 metres. The figure is only meaningful when you read it against your exact model and your actual cable length.
Quick answer
- Cable size is the conductor area in mm². A larger number means a larger conductor for the same run.
- Victron’s table lists one cable per battery connection for most rows, and two cables for some 3000 VA and 5000 VA rows in the 5 to 10 metre column.
- Some rows are marked “Not recommended” for the 5 to 10 metre run. Treat that cell as a limit, not a suggestion.
- The chassis-to-ground conductor should be at least half the cross-section of the battery cables.
- Read the cable size together with the fuse rating and the battery capacity range for the same model row.
What the cross-section figure means
Cross-section describes how much conductor area the cable has when you cut it straight across. In the Victron table it is written as a number followed by mm², for example 1 x 70mm². The figure tells you the conductor size. It does not tell you the cable’s insulation, its conductor material, its temperature rating or its voltage rating. The three Victron pages used for this post do not state those properties for any cable, so do not assume them from the table.
The table is also a minimum guide from the manufacturer for the Inverter Smart range. It is not a general rule for every inverter, and it does not replace the local installation rules that the same page tells you to follow.
How the Victron table is laid out
The installation page gives one row per model with five columns: the cable cross-section for a run of 0 to 5 metres, the cable cross-section for a run of 5 to 10 metres, the recommended fuse rating, and the battery capacity range. The table below restates those figures in our own layout. The numbers come from the Victron installation page, copyright 2025, opened 2026-10-27.
| Inverter model | Cable, 0 to 5 m | Cable, 5 to 10 m | Fuse rating | Battery capacity |
|---|---|---|---|---|
| 12/1600 | 1 x 70 mm² | Not recommended | 250 A | 300 to 800 Ah |
| 24/1600 | 1 x 35 mm² | 1 x 70 mm² | 125 A | 150 to 400 Ah |
| 48/1600 | 1 x 16 mm² | 1 x 25 mm² | 60 A | 75 to 200 Ah |
| 12/2000 | 1 x 70 mm² | Not recommended | 300 A | 350 to 1000 Ah |
| 24/2000 | 1 x 50 mm² | 1 x 95 mm² | 150 A | 200 to 500 Ah |
| 48/2000 | 1 x 25 mm² | 1 x 50 mm² | 80 A | 100 to 250 Ah |
| 12/3000 | 1 x 90 mm² | 2 x 70 mm² (*) | 400 A | 400 to 1200 Ah |
| 24/3000 | 1 x 50 mm² | 2 x 50 mm² (*) | 250 A | 200 to 700 Ah |
| 48/3000 | 1 x 35 mm² | 2 x 35 mm² (*) | 125 A | 100 to 400 Ah |
| 24/5000 | 1 x 90 mm² | 2 x 95 mm² (*) | 400 A | 300 to 1500 Ah |
| 48/5000 | 1 x 70 mm² | 2 x 70 mm² (*) | 200 A | 150 to 700 Ah |
The model label has two numbers. The specification page lists battery connection options at 12 V, 24 V and 48 V, and continuous output ratings of 1600 VA, 2000 VA, 3000 VA and 5000 VA. The first number in each label appears to match the battery voltage and the second matches the VA rating. The pages do not spell out the naming rule, so treat the label as an identifier for the row rather than a calculated value.
Why cable run length changes the answer
The Victron installation page advises keeping the distance between the inverter and the battery as short as practical, because longer cable runs lose more voltage. That is the reason the table has two columns. The same model can need a thicker cable once the run passes 5 metres.
Take a 24/1600 with a 7 metre run. The 0 to 5 metre column says 1 x 35 mm², but 7 metres is outside that band. The 5 to 10 metre column gives 1 x 70 mm², so that is the row to use. A 12/1600 with the same 7 metre run is a different case: the table says “Not recommended” for the 5 to 10 metre band, and the page does not offer a replacement cable size for that cell. In that situation the table is telling you to change the design, not to buy a bigger cable and hope.
The rule of thumb in plain words is simple. Measure the actual run, not the straight-line distance on a drawing. Add the slack you will route through the enclosure. Then pick the column that contains your number.
The two-cable rows and the rated fuse current
Five rows in the 5 to 10 metre column show two cables per battery connection and carry an asterisk. These are the 12/3000, 24/3000, 48/3000, 24/5000 and 48/5000 models. The note under the table says one of the cables must be sized to carry the rated fuse current without overheating. That is a sizing requirement, and it means the pair of cables is not a way to reduce the size of each cable below the figure printed in the table.
Some readers ask whether two smaller cables can replace one larger cable in a row that shows only one cable. The Victron pages do not say that. For single-cable rows, use the printed size. For two-cable rows, use the printed sizes and keep the note in mind.
The chassis-to-ground conductor
The installation page says the earth conductor running from the earth lug on the chassis to ground should have at least half the cross-section of the conductors used for the battery connection. On these models the earth lug on the chassis is an M6 bolt. As arithmetic from that rule, a 1 x 70 mm² battery cable pairs with an earth conductor of at least 35 mm². A 1 x 35 mm² battery cable pairs with at least 17.5 mm². This is our calculation from the page’s rule, not a separate figure from Victron.
Battery capacity and cable size work together
The technical specifications page and the installation page both say that the inverter needs a battery with sufficient capacity and battery cables with sufficient cross-section to make full use of the inverter’s output. The table gives a battery capacity range for each model. A row with a large inverter and a small battery bank is outside what the table describes, even when the cable size looks correct.
The pages do not explain the physical reason behind each range. They also do not say how the ranges were chosen. What you can do with the information is check that your battery bank falls inside the range for your model before you choose the cable.
Installation rules printed with the table
- Do not run battery cables inside a closed conduit.
- Follow local installation rules. The Victron page says so directly.
- Avoid shorting the battery cables. Use an insulated box spanner when you tighten the battery connections.
- The maximum torque for the battery terminals is 11 Nm. Tighten to that figure and not beyond.
- Connect the red cable to the positive terminal and the black cable to the negative terminal.
- Reverse polarity connection will damage the inverter, so check both ends before you power anything.
- Keep the distance between the inverter and the battery as short as practical.
How to use the table, step by step
Follow these steps in order. Each one maps to a figure the Victron pages print, so you do not need to guess.
- Find the row that matches your inverter model exactly. A 24/2000 row does not apply to a 24/1600.
- Measure the cable run from the inverter battery terminal to the battery terminal, and decide whether it falls in the 0 to 5 metre band or the 5 to 10 metre band.
- Read the cable cross-section for that band. If the cell says “Not recommended”, stop and rethink the layout or the model.
- If the row shows two cables, use the printed size for each and keep the rated fuse current note in mind.
- Check that your battery bank sits inside the battery capacity range for that row.
- Size the chassis-to-ground conductor at no less than half the battery cable cross-section.
- Read the fuse rating for the same row before you choose the fuse, because the cable and the fuse are specified together.
The Victron pages do not give you a voltage drop calculation or a maximum current for each cable product. If you need one, get it from the cable supplier and the local wiring rules, not from this table.
How we chose these sources
We used three Victron Energy pages from the Inverter Smart manual. The installation page holds the cable table and the battery connection rules. The technical specifications page holds the model list and the battery connection specifications. The safety instructions page covers the warnings that apply to battery connections. Each page shows a copyright year of 2025 and no revision date, which is why the source date in this post is the copyright year. We opened all three on 2026-10-27. We did not use the Sun Inverter or MultiPlus-II pages for this post, because they describe other models and the Inverter Smart table does not map to them.
What we could not verify
- The sources do not state insulation type, conductor material or temperature rating for any cable.
- The sources give no voltage drop percentage and no formula for one.
- The sources do not explain how the battery capacity ranges or the cable sizes were chosen.
- The sources do not say which commercial cable products meet the printed cross-sections.
- The sources cover Inverter Smart models only. They say nothing about other inverter brands.
- The sources do not explain what to do in a “Not recommended” cell beyond the cell itself.
Mistakes to avoid
- Reading a row for a different model. The 12/1600 row and the 24/1600 row give different sizes for the same run.
- Choosing the 0 to 5 metre column for a run that is longer than 5 metres.
- Ignoring a “Not recommended” cell because the cable looks thick enough.
- Skipping the chassis-to-ground conductor, which the page treats as a separate sizing rule.
- Running battery cables through a closed conduit.
- Reversing polarity at the battery terminals, which the page says will damage the inverter.
- Choosing a battery bank outside the capacity range for the model.
FAQ
What does 1 x 70 mm² mean on the Victron table?
It means one cable with a cross-section of 70 square millimetres for that battery connection. The table prints it for the row and the run length shown in the same line.
Can I use two smaller cables instead of one larger cable?
The table shows two-cable rows only for some 3000 VA and 5000 VA models in the 5 to 10 metre column, and the note requires one cable to carry the rated fuse current. The Victron pages do not say that two smaller cables can replace a single larger cable in other rows.
Why is 5 to 10 metres “Not recommended” for the 12/1600?
The table prints the cell without a reason. The installation page does say that keeping the distance short reduces cable voltage losses, which is the general concern behind any run-length limit. Beyond that, the sources do not explain the cell.
How big does the chassis earth cable need to be?
The installation page says at least half the cross-section of the battery conductors. For a 1 x 70 mm² battery cable, that is at least 35 mm² by the page’s rule.
Does this table cover solar charge controller cables?
No. The table covers the battery connection to the Inverter Smart. Other cables in a solar system are outside the scope of these three pages.
Bottom line
Use the row for your exact model, the column for your real cable run, and the printed cross-section for that cell. Treat “Not recommended” as a stop sign, and check the fuse rating and the battery capacity range before you buy any cable.
Related guides
- How to check a fuse with a multimeter covers the fuse side of the same circuit.
- How do you use a multimeter step by step is a starting point if the meter is new to you.
- Best multimeters for solar panel work lists meter types for solar wiring checks.
Sources
- Victron Energy, Inverter Smart manual, “Installation” page. https://www.victronenergy.com/media/pg/Inverter_Smart/en/installation.html. Copyright 2025 Victron Energy, no revision date shown. Opened 2026-10-27.
- Victron Energy, Inverter Smart manual, “Technical specifications” page. https://www.victronenergy.com/media/pg/Inverter_Smart/en/technical-specifications.html. Copyright 2025 Victron Energy. Opened 2026-10-27.
- Victron Energy, Inverter Smart manual, “Safety instructions” page. https://www.victronenergy.com/media/pg/Inverter_Smart/en/safety-instructions.html. Copyright 2025 Victron Energy. Opened 2026-10-27.
