Prototyper of the Week

Flo Labs Breaks Down a Problem

Every week, we recognize the Highway1 team that was most active in the lab with the prestigious Prototyper of the Week award.

This week’s winner is Flo Labs and their impressively rigorous approach to identifying and working through a potential problem. We thought it would be instructive to get the lowdown from Flo Labs CEO and co-founder West Askew:

We found that our inductive charging module was heating to a point that we thought might affect battery life or cause some sort of failure. So we went through a series of different processes to understand the actual risk of overheating, using a methodology called Design Failure Modes and Effects Analysis (DFMEA), something I have some experience with from working on medical devices. Most of the time, it takes the form of a document you have to give the FDA that captures every component of your design: what are the failure modes and the resulting effects? You list every possible outcome and rate each based on severity of the effect, and based on those factors, you come up with mitigating actions. When we’re doing less-rigorous benchtop troubleshooting, that’s what I’ve got going through my head: a DFMEA.

For example, with this battery, it wasn’t necessarily an issue of “How is this device functioning?” more than “What are the potential problems if it gets too hot?” We looked at the spec sheet for the inductive charging module and found that ours was hotter than the spec by 10°, so we looked at the module and the things around it: what would happen if they got hot?

  • Was the circuitry on the module itself going to function properly? We found that it did.
  • Was the housing going to warp or deflect? We looked into the material properties of the housing and did some simulations, and found it wasn’t going to warp at those temperatures.
  • Were any of the surrounding adhesives going to be affected? We found out they wouldn’t.
  • What about the battery itself: was the battery life going to be affected? The number of charge cycles the battery could go through, or its charge rate, or its ability to hold a charge? In all cases, no.


We also did some benchtop tests to make sure there wasn’t a problem with the charger that we were using. We tested the module we intended to use along with a certified, known development module; we put an inductive charger on both of them for a side-by-side comparison to see if one got significantly hotter than the other. It turned out they didn’t: they were within 2-3° of each other. In the end, having gone through a bunch of different steps and consulted with the Highway1 electrical engineering staff, we determined it wasn’t going to be an issue for the purposes of our beta program.

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