What kind of fuse to use to connect between charger/converter and battery?

[jbeard4]

Hello,


I ordered a new 100Ah LiFePO4 battery, a 60A Progressive Dynamics converter/charger, and a 4 AWG copper wire cable to connect the charger/converter to the battery, all from Battleborn. I was wondering if I should add a fuse inline between the converter/charger and the battery? If so, what kind of fuse should I use?


Battleborn sells a 300A fuse kit, but an article and chart on their site seems to indicate that this is too much fuse for a 60A circuit:




I would appreciate any insight anyone can share on this. Thank you for your help,



Jake

[richard5933]

The Progressive Dynamics has fuses onboard and I don't see any mention of adding additional inline fuses in their manual.

However, adding fuses between the batteries and the system is a good idea. I've seen these called 'catastrophic' fuses before, with the main goal to protect things if there is a dead short somewhere. With lithium batteries this is even more important in my book since they have a potential for very high current on a dead short.

My understanding is that the ideal fuse is a class T since it will blow quickly and cleanly. This fuse should be close to the battery bank. Sizing the fuse depends on how big your largest load on the batteries will be, not the size of your converter. In your case with one battery, you still might have a load larger than your converter if you use an inverter, so check to see what your largest combined load might be when sizing the fuse.

There are class T fuses made in sizes less than 300 amps. There are a few size categories, along with a few different physical sizes for the fuses. I've got a Blue Sea fuse holder in my trailer, and there holders are sized to hold either 110a-200a fuses or 225a-400a fuses. In your situation, you could likely be fine with the smaller Blue Sea fuse holder.

https://www.bluesea.com/products/cat..._T_Fuse_Blocks

Using one of their smaller fuse holders would allow you to put a 110a fuse in to protect the system.

Another option is using ANL fuses, which are available in a wider variety of sizes.

[Dingo Girl]

I know zip about lithium batteries.
But this is what I used with my AGM lifeline battery.
Available thru VTS.
The following is their description :

This 50 amp DC circuit breaker features a cycling automatic reset. They are used in many applications, but in a properly wired 12v system, one should be installed on the line running between the positive terminal of your battery and your DC fuse box, within 18" of your battery. You will probably be using one with your breakaway switch too.

[Tasml]

I used a Blue Sea terminal mount double MRBF fuse block. Fuse (1) is 100a for my main DC system (factory 6 gage) including a Progressive Dynamics 60a converter. Fuse (2) is also 100a for my 1000 watt WFCO inverter circuit (factory 4 gage). WFCO documentation recommends a 100a fuse here even though the original factory Airstream setup had none. I went this way because the setup fits quite nicely in my system, however, it is not Class T. My current draw, even under heavy electrical usage, has always been significantly below 100a.