Our technicians at Battle Born Batteries have recently spoken with many customers reporting a heat build-up at their fuse and fuse holders. We wanted to take a moment to share the importance of using high-quality fuses and fuse holders in your system. 

What is a Fuse? 

A fuse is an electrical safety device built around a conductive strip that is designed to melt and separate in the event of excessive current. Fuses are always connected in series with the component(s) to be protected from overcurrent so that when the fuse blows (opens) it will open the entire circuit and stop current through the component(s). 

Customer safety is our top priority and that is exactly why we recommend higher quality fuses. These fuse holders not only keep you safe, but also protects your Battle Born Batteries. We know our batteries are an investment, and fuses are a cost-effective way to help protect them if there were to be an over current.  

Fuse Ratings 

Fuses are primarily rated in terms of maximum current, in addition to terms of how much voltage drop they will safely withstand after interrupting a circuit. Their operation depends on the self-generation of heat under conditions of excessive current, by means of the fuse’s own electrical resistance. Fuses are engineered to contribute extra resistance to the circuits they protect. Fuses can be designed to blow fast, slow, or anywhere in between for the same maximum level of current. 

Just as a normal wire, the ampacity (the maximum amount of current that a wire or cable can safely carry) is not related to its length. A fuse wire of certain material and gauge will blow at a certain current no matter how long it is. Since length is not a factor in current rating, the shorter it can be made, the less resistance the fuse wire will have end-to-end. 

However, the fuse designer must also consider what happens after a fuse blows. The melted ends of the once-continuous wire will be separated by an air gap, with full supply voltage between the ends. If the fuse isn’t made long enough on a high-voltage circuit, a spark may be able to jump from one of the melted wire ends to the other, completing the circuit again. 

Why Go with the More Expensive Option? 

Some of our customers have contacted us about the heat build-up in their fuses. These issues have been directly connected to lower cost ANL fuse and fuse holders, typically bought from online retailers like Amazon. 

These less-expensive fuse holders feature a clear, plastic base using very minimal metal to act as a heat sink. While these fuse holders will work great for car audio systems, they will more than likely get too hot for mobile power systems. Some of our customers have used a heat gun to record temperatures between 175- and 200-degrees F at the fuse and holder in their mobile power systems! 

Finding a more cost-effective solution for your fuses sounds great initially. However, buying the wrong or inefficient supporting components can create a potential hazard in your lithium battery system. 

When it comes to fuses, it is worth investing in a higher quality product. We sell three fuse kits in our shop: a 300 A Fuse Kit, 400 A Fuse Kit, and 500 A Fuse Kit. All three of our fuse kits are priced at $35. These fuses are more costly upfront than a traditional glass fuse, as they are ceramic and contain a significant amount of metal. Ceramic fuses are more reliable and durable during high-current events as they contain sand, which extinguishes any arcs that appear when the fuse blows.   

Our recommended fuse holders have a high amount of metal built into the base, which acts as a heat sink and allows for a more consistent operating temperature at the fuse and cable under high loads. Using a higher quality fuse holder held one of our customer’s temperature under 95 degrees F while running an 1800 watt load for an extended period! 

I Have the Fuses, Now What? 

Proper assembly of the fuse holder, cables and fuse is necessary to protect your investment. Making sure the hardware is properly installed and torqued is the final step to ensuring proper function of your fuse in the system. Correct orientation of the cable and fuse is as follows, listed from top to bottom. 

Directions for fuse replacement: 

1. Remove cover 
2.  Remove nut, spring washer and flat washer.  
3. Replace fuse 
4. Replace (in order) flat washer, spring washer, and nut  
5. Fastener torque:  
6. 5/16’-18 144 in/lbs. [16.2 Nm] 
7. 3/8’-16 180 in/lbs. [20.3 Nm] 
8. M10 x 1.5 180 IN/LBS. -20.3 NM] 
9. Replace protective cover 

Battle Born Batteries recommends you run, not walk, away from cheap fuses when top quality fuses are relatively inexpensive. It’s a small price to pay to help protect your investment in Battle Born Batteries and keep everyone safe in regards to your electrical system. 

Also, Battle Born partner Nate Yarbrough from Explorist.life is a master at fuse installation. There are many blogs and diagrams like the one above on his website. For more in-depth reading, check out Nate’s blog called “What size fuses to use for a DIY camper electrical setup.”  He also has a very helpful fuse size calculator.  

For questions on fuse sizing, install or other technical questions, please call Battle Born Batteries at (855)-292-2831 or email us at [email protected] to speak with one of our sales technicians.