Hi @schwac! I’m really excited to chat about this topic!
You are correct that Bristlemouth uses two connectors, each with only one conductor. Although it may seem frustrating to have to plug two connectors in instead of one, this design allows each connector to be built extremely reliably which in our experience is the single most important factor for marine connector design. For a myriad of reasons (which I ought to post about sometime), this allows the connector to be much more robust and reliable in the field, and also removes failure risks in the manufacturing phase.
We’ve been using Bristlemouth connectors internally at Sofar for several years and depend on the design for our entire fleet of thousands of buoys and Bristlemouth devices that plug into the Spotter Smart Mooring ecosystem. At this point the modern connector design has gone through several million accumulated hours of in-ocean use time and we have experienced zero (!) failures from the connector itself.
We currently build a device called a “Bristlemouth Mote” at Sofar, which translates Bristlemouth into other protocols (I2C, RS232, etc.) and breaks out power output from the 24v bus voltage to the voltage needed. Right now, the Mote is limited to around 10 Mbps, but we’re exploring designs for higher speeds since standards exist for 100 Mbps or more over two wires.
The protocol being used (Single Pair Ethernet) is pretty robust against messy wiring. Speaking at least for the 10Base-T1L we use, none of that has seemed to matter for the situations we’ve used it in.
The intention of the Bristlemouth standard is to allow 3rd parties to make the hardware for it as well. Since Sofar is the biggest user of the standard at this point, it’s made sense to lead the charge in manufacturing that hardware, but it would be great to see it start to be available from others. The standard is open, however to keep a quality standard maintained, there will likely be some technical approval process for things to be “Bristlemouth Certified” much like how USB or Bluetooth devices need to go through some process and rigor to display those logos. The details of this process are still being worked out.
I appreciate your suggestion about supporting 48V systems. It’s a great idea, especially with the trend toward that voltage in automotive applications. As I’m sure you’re aware (just saying this for anyone else who’s reading) 48v is about the highest one can go without being considered dangerous, and with that higher voltage, more power could be delivered with the same electrical current limits. That being said, it presents challenges with regulation efficiency and higher susceptibility to connection failure. Like higher bandwidth connections, I think this something worth exploring more in the future, epically as components that readily support 48v become more ubiquitous.
Thanks for your thoughtful questions and suggestions - this is one of my favorite things to talk about so I hope we can keep the conversation going!
Eric