Sapphire Energy
4 AWG Battery Cables (21mm²)
4 AWG Battery Cables (21mm²)
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4 AWG Battery Cable with Ring Terminals
Build clean, dependable high-current connections with a ready-to-install 4 AWG battery cable. Each cable uses a heavy-duty 21 mm² ultra-fine-strand oxygen-free copper (OFC) conductor with a durable PVC jacket and tinned copper ring terminals installed on each end.
Choose the colour, cable length and lug size required for your installation. These cables are well suited to batteries, inverters, busbars, disconnect switches, fuse holders and other high-current DC equipment.
Each quantity includes one cable in the selected colour, length and lug size. Order one red and one black cable if you need a conventional positive-and-negative cable pair.
Why You’ll Love It
- Ready to install — ring terminals are already fitted to both ends
- Heavy-duty 21 mm² OFC conductor — closely matches standard 4 AWG
- Ultra-fine-strand construction — flexible and easier to route through tight installations
- Choose your length — get precisely what you want
- M8 lug terminals — sized for common 5/16″ battery, fuse holder and busbar studs
- Red or black jacket — clearly identify positive and negative wiring
- Individual cable ordering — purchase only the exact cables you need
The stocked cables in this listing have M8 lugs on both ends. M8 fits an approximately 5/16″ stud. Need M10 or different lug sizes at each end? Contact us about another configuration.
Suggested Applications
- Battery-to-inverter connections
- Battery-to-busbar connections
- Battery disconnect switches
- Class T, ANL and MEGA fuse holders
- Short high-current equipment jumpers
- Battery-bank series or parallel interconnections
- RV, van, marine and off-grid electrical systems
- Backup power and mobile equipment installations
Specifications
| Nominal Cable Size | 21 mm² |
|---|---|
| Approximate AWG Equivalent | 4 AWG |
| Conductor Material | Oxygen-free copper (OFC / pure copper) |
| Stranding | Ultra-fine strand |
| Insulation | PVC |
| Lug Material | Tinned copper |
| Lug Options | M8 (5/16″) |
A positive cable connected to a battery should normally be protected by an appropriately rated DC fuse installed as close to the battery as practical. The correct fuse type and rating depend on the cable application, connected equipment and available battery fault current.
What’s Included
- 1 × 4 AWG / 21 mm² battery cable at your selected length and colour
Frequently Asked
Is this listing for one cable or a red-and-black pair?
This listing is for one individual cable. Select red or black when ordering. Add one of each colour to your cart if you need a conventional positive-and-negative pair.
Is 21 mm² exactly the same as 4 AWG?
They are effectively equivalent for product selection. Standard 4 AWG has a conductor area of approximately 21.2 mm², while this cable is specified as 21 mm².
What is OFC cable?
OFC stands for oxygen-free copper. It is pure copper cable rather than copper-clad aluminum, providing excellent conductivity for high-current battery and inverter connections.
What does ultra-fine strand mean?
Instead of using a small number of thick copper strands, the conductor is made from many very fine strands. This makes the cable more flexible and easier to route around batteries, inverters, fuse holders and other equipment.
How do I choose the lug size?
The stocked 4 AWG / 21 mm² cables use M8 lugs on both ends. M8 is approximately 5/16″. Contact us if you require M10 or mixed lug sizes.
Do both ends have the same lug size?
Yes. The stocked cables in this listing use M8 lugs on both ends. Contact us if you require M10 or different lug sizes at each end.
Why is only M8 currently listed?
The stocked 4 AWG / 21 mm² assortment currently uses M8 lugs in 15, 30, 60 and 90 cm lengths. Contact us if you need an M10 or mixed-lug cable.
Are red and black cables electrically different?
No. Cables with the same conductor size, length and lug configuration are electrically equivalent. The jacket colour is used to identify polarity and make the installation easier to inspect and service.
Can I use this cable with a lithium battery?
Yes, provided 4 AWG / 21 mm² cable is appropriately sized for the system current, circuit length and installation conditions. These cables can also be used with other battery chemistries when properly selected and protected.
What size inverter can I connect with 4 AWG cable?
Cable suitability cannot be determined from inverter wattage alone. Battery voltage, maximum DC current, total positive-and-negative circuit length, ambient temperature and installation method must all be considered. Follow the inverter manufacturer’s cable and fuse requirements.
Do I need a fuse?
Usually yes. Positive battery wiring should normally be protected by a properly selected DC fuse located close to the battery. The fuse is intended to protect the cable if a short circuit occurs. Always verify the required fuse type and rating for your equipment and battery system.
Can you supply a custom length or mixed lug configuration?
Yes. Sapphire Energy can build other cable lengths and lug combinations. Include the required cable size, finished length, colour and lug size for each end when contacting us.
Tell us your battery voltage, equipment model, maximum current, required cable length and connection stud sizes. We can help you select suitable cable and fuse protection for the installation.
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