Hurricane? Yes. Postal Service? No.

A project log for Turtle Sense

Cell phones for Sea Turtles and beyond -- creating an extremely low powered remote data recorder and sensor for monitoring wildlife, etc...

Samuel WantmanSamuel Wantman 08/06/2014 at 07:040 Comments

So, we got through Hurricane Arthur without a problem, and we decided to send some more Communications Units into the field. We sent them out via the USPS Priority Mail. The units are housed in schedule 40 PVC pipe, which is really, really strong, so we thought that there wouldn't be a problem in the mail. We were wrong. It turns out that we planned for everything except for the abuse that the units would receive in transit.

Most everything in the device is soldered together, but there are a few connections that are not. The cell phone board is plugged into headers. There are several boards available from the manufacturer that work with different telecoms. The boards could be soldered in, but we wanted to be able to swap in a different board for different carriers if need be. With 49 pins holding it in, it takes quite a bit of effort and wiggling to get it out and seemed very, very secure. But not secure enough for the USPS! Similarly, the eight AA batteries are secured in a battery pack, and the pack can be unplugged with a standard 9 volt battery clip. These take quite a bit of force to put on and take off, but the trip cross country in the mail was enough to shake it loose. None of the units in our last shipment was working by the time they made it from California to North Carolina.

The repair for these problems is very simple, and in retrospect we might have anticipated this issue. To secure the board and the battery clip, we tightened cable ties around them. There is no way to get them loose without cutting the ties off.

So the moral of the story is, when you are designing a product, don't worry about making it hurricane proof. Make sure it can make it through the post office.