A team I’m working with has a need for more energy than the spotter can provide. We need about 5W continuous and even though we can probably draw enough power, the application could not run for very long as we would deplete the spotter battery and solar production quickly. We are thinking of connecting a 24V battery and solar directly to the surface float node of the smart mooring. If we just applied 24V across the connectors without a mote would there be any unforeseen issues? I get that a smarter system with a mote could communicate state of charge, etc but we need something simple for a project that gets put in the water in March.
The most simple way to do this is is to hook-up your power source to one side of a mote, and the network to the other side. Each port on a Mote has a PoDL circuit at its interface and are separated. This would be the block diagram:
This may not be ideal if you want to put power at the first node with the surface float but also another Bristlemouth enabled node downstream.
OPTION B – HARD WAY
Adding power to a node this way is not a straightforward thing to do but it is possible with the caveat that we haven’t tested anything like this and you may damage the board.
If you’re inclined to try it:
Power should be provided into the network through the PoDL sub-circuit in order to prevent the power source from interfering with the data transmission. This might not be strictly necessary depending on your power source, but probably will be.
There are two test pads on the bottom of the BM Mote that can be used for this. Separate the Mote from the Bristlemouth Dev Board and find the two test pads TP22 [VBUS] and TP23 [GND]. Shown in red circles on the schematic which is found here.
Any power source should be limited to 1A to avoid damaging Motes in the case of a short condition on the bus.
We have added a feature request to create a BM battery/power supply adapter module. This would be a small simple sub-circuit that has a PoDL and an adjustable current limiting switch to make it easy to plug in any power supply into a BM network.
One thing that would be helpful is to see a diagram of the deployment you plan on with what payload you plan on using. This could help us make specific recommendations.
