SparkFun Buck-Boost converter failing with 14.5v or higher

Components & Accessories Power
1

Hey guys, we are building some devices for vehicles, and using the Buck-Boost converter (COM-15208) to step down power from 12v-14V switched battery power to 5V to power a Raspberry Pi Zero.

This unit is rated to accept up to 16V, but we have seen some Buck-Boost board failures in this application where the boards get physically burned and fails. It happens around 14.5V when we bench test them.

The units always seem find when connected to 5v USB power, but the battery power is sometimes a problem. We are not exceeding 16V at any time.

Can anyone from SparkFun help? I have a couple hundred of these boards on the shelf. Any other customers experience this?

Thank you!

2

So, I went poking through the datasheet and pages 4 and 14 in there make me think it’s only recommended for 34.5% duty cycle at 14.5v in and 5v out
VOUT = 5V: D = 5/14.5 = **34.5%
**
At 5v output and 14.5 input the device has to dump more energy as heat waste (because the ratio is high). The charts for efficiency above 12v aren’t plotted either, but 12v is the least efficient and you’d expect more would be worse based on the ones that are plotted :-/