Captain’s Log 06/20 – 06/26
June 20, 2021 – Three weeks (well sorta)!
LoCARB has been having trouble charging these past two days because there’s major cloud cover over where it’s located. I’ve turned the motor off but even still, the voltage drops below what it needs to keep the Arduino companion computer powered and it goes dark for a few hours during night time before the solar panel can recharge the batteries again. I think it will do it again tonight/tomorrow since voltage is below 11v.
Overall health of the boat is functional, but in “low performance mode” (it was never high performance ha!). The propeller connected (or disconnected now) to the primary motor is non-functional, so LoCARB is running on its backup thruster. This thruster is less power efficient than the primary one, so it runs a little slower when on. The boat motor pod humidity still climbs a tiny bit, and I’m surprised the electronics (battery, BMS, charge converter) still functions decently enough. Will it last another week? A month? A year!?
The boat is currently adrift since the motor is off waiting for a full battery charge, but its so far away from the coast of Mexico I’m not worried about it. I wonder what its like out there…
4:57 pm: Motor off and update interval changed to 4 hours between each update.
June 22, 2021
Some thoughts going through my head. Why is the boat voltage despite being charged for the past two days never moving past 12v? Has one of the parallel cell rows gone bad due to water ingress? I have a 4S10P 18650 battery pack. This effectively means 4 rows of 10 batteries x 4.2v = 16.8v. If one row of batteries happens to die, this would equal only 3 x 4.2v = 12.6v. The way the batteries are wired make this unlikely, however, if the battery management system circuit board has been damaged by water ingress, it could potentially keep the 4th row of batteries from charging. They will get some charge since they are connected by tin strips to the adjacent rows, but they would effectively be charged in an unbalanced way and potentially cause the row it is soldered to to lose its charge as well.
Ultimately, I wont know till I see clear skies with no clouds. If I get a day with this and the voltage remains below 13v, ill know water ingress has caused damage to the power system.
Despite this, I’m really enjoying the journey LoCARB has taken. I wonder what kind of encounters with curious sea creatures it’s had, and how many birds have rested on its solar panel. Are barnacles growing on it? When we launched the boat last, we saw a sea lion swim up to the boat to check it out. I wonder if any sharks have done the same…is that why the propeller is no longer functional?
June 26, 2021
4:56 pm: LoCARB sent a message with bad coordinates and voltage readings which means the autopilot has lost GPS lock. Just to be sure its not the Pixhawk freezing up, I power cycled both Arduino and Pixhawk, sent a new waypoint, and turned off the motor again. Lets see what happens.
On a more positive note, these past few days LoCARB has miraculously drifted back in the right direction.
And is 530 miles from the coast of Baja California