A demanding UL 2054 short-circuit test shows how even LiFePO4 batteries can go wrong when the BMS fails—especially when a fuse is missing or ineffective. Videos by Will Prowse highlight units that pass by blowing fuses, alongside batteries that fail in ways th
When the battery management system (BMS) fails and creates a direct short, the difference between “safe” and “catastrophic” can come down to a single component: the fuse.
That’s the tension running through a recent set of videos by Will Prowse. focused on LiFePO4—often called LFP—batteries. LFP chemistry is generally described as safe and stable, but the tests still assume that something can go wrong. In this case, the failure scenario is specific and severe: a BMS developing a direct short.
The short-circuit test Prowse demonstrates is one of the requirements tied to UL 2054. the standard that targets household and portable battery safety. It’s not enough for a battery to have basic protection. The failure has to be detected immediately, and some fail-safe mechanism—like a fuse—has to take over right away.
In the first two commercial batteries shown, the test outcome matches the expectation: both pass by blowing their fuse. The result is what the certification is designed to prove—when things go bad, the battery doesn’t keep feeding the fault.
The second unit is also notable in a different way. It isn’t even UL-listed, yet it still includes multiple layers of safety that allow it to get through this particular short-circuit challenge.
Then the video turns sharper. The third unit is a “Li Time” LFP battery, the kind of product a buyer might pick up from an online retailer. It has a basic BMS and a typical battery configuration, but it’s missing a prominently placed, chunky fuse. LiTime also claims UL 2054 certification.
The problem, according to the demonstration, is straightforward: there’s no fuse in place to prevent a thermal runaway event if the BMS were to short. Without that immediate interrupt, the protection story doesn’t hold up under the same demanding condition UL 2054 is meant to cover.
The final battery tested is made by Battle Born. Here, the issue is described as the battery catching fire because its purported thermal safety does extremely little to interrupt the current. In other words, the “thermal” protection isn’t stopping the fault from continuing long enough to matter.
Taken together, the demonstration pushes a clear message for anyone buying or building systems powered by LFP batteries. Look for safety features such as internal fuses. It can also be wise to add terminal fuses to batteries. specifically so dangerous currents can be interrupted at the points where they’re most likely to turn an electrical problem into a physical hazard.
Prowse’s videos end on a simple, hard-learned priority: it’s better to replace a blown fuse than to deal with an out-of-control inferno—and the potential for violent hydrogen detonation—when protection fails to do its job in the moment it’s needed.
LiFePO4 LFP batteries UL 2054 BMS failure fuse safety short circuit test battery safety Will Prowse LiTime Battle Born
So if the fuse is missing it just… explodes? Glad they’re testing this stuff.
I don’t get how a battery can be “safe” but still fail UL stuff. If it’s LiFePO4 why does it even need all these extra layers? Sounds like marketing tbh.
Wait I thought LFP was basically foolproof? Like my cousin uses one for his solar and it’s fine. But if the BMS shorted and the fuse blew, isn’t that still the battery doing what it’s supposed to? Or is the problem that it’s not UL-listed but still claiming it is…
This is why I don’t trust anything I buy online labeled UL anything. Also the title says “fuse gaps” like it’s a design flaw and not just the tester being picky. I mean, batteries always have issues right? Just put the fuse in and stop pretending. LiTime sounds like the kind of company that says it’s certified then leaves out the one thing that matters.