power

It's best to use either a true bench-top power supply or batteries. Either way, supply can be between 7V and 28V, with negative on the outside of the barrel. Power consumption is up to 0.75W (with something like 2/3 of that going to to the MicroSquid). Note that there is no "sleep" or power-down mode: the squid is powered up as long as it is connected and the freebird has power.

A new set of 6 CR123 cells will last for a long day of sampling, designed for roughly 18 hours in 10degC water.

Power Details

The MicroSquid-C takes 0.5W at 4-32V (it has two internal DC-DC converters).

The Teensy is a constant 20mA at 5V, and with the external DC-DC converters I think that came out to 16mA at 9V, or 0.14W. While the SD card during writes can draw a lot more than this, it's sufficiently short-lived that the average power is still around 0.14W.

Since CR123 (3V lithium camera batteries) are easy to find and also fit RBR loggers, they're a good choice for powering the freebird. A typical CR123 is rated for maybe 3.8 Wh at room temp, and something like 3Wh when cold but not freezing cold.

With total freebird power consumption around 0.64W, a 16 hour work day comes out to 10.24 Wh or 3.4 batteries.
Could get by with 4 CR123, but to be safe, it holds 6. Since the logger and the microsquid-c are rated for a wide range of supply voltages, it could be run from 4 cells with shunts in the remaining slots. 3 cells may be pushing it, since the voltage may droop below 7V sooner than the power capacity implies.

Exhausting the batteries, in limited tests, has proven not to be catastrophic. Data is sync'd to the SD card quite often (seconds, not minutes). There is not any explicit brownout detection, but the fact that the MicroSquid remains connected and will continue drawing current even after the logger shuts down reduces the danger of low-voltage cycling (otherwise, it could get into a loop where voltage drops, it shuts down, the no-load situation allows the battery voltage to recover, it boots up, voltage drops, repeat...)