Stuff I Could have Learned...

Today you woke up on time for school and ready to work on the project! You went to Nick's house after dropping your brother off for school and sat in a chair for a while. After reading up on different things for the project you went upstairs to make sure Nick was alive....

At Nick's you ordered a half-sphere for the submersible and decided what to do with the oversized batteries (oversized for our 8in float). You also thought you figured out how to measure the battery voltage of the batteries, but were mistaken (as you found out later that evening).

After finished up at Nick's, both you and Nick went back to your house. While at your house you ordered the final HobbyKing motors and ESCs. Unfortunately for you, they were out of the ESCs we had been using, but it ended up working out as the slightly stronger ESCs would still work for our thrusters.

You also tested running processes in Python using Threads (which worked very nicely). The software for the sub and float is finally coming together.

Around 12:00 you and Nick stopped by the bank and then headed over for the AP Physics test...

After the test you went to Frisbee practice (which you thought was sweltering hot) and then you went to swimming. After swimming you ate 3 hamburgers and a big bowl of pasta. Around 20:15 Jessica came over after her softball game and Nick came to drop off his gear for Model UN.

At 22:15 you drove Jess home and then started working on the voltage divider you thought would work to measure the voltage of the battery on the float. Using this simple formula (below) it was supposed to be easy to step down the voltage of a system. By stepping down the system you could then read the analog output from the battery easily through the ADC on the BeagleBone Black.

But sadly nothing is easy...it seems that the 1/4 Watt resistors didn't have a large enough power rating to handle the current (although nothing was being drawn...). You proffer this using Joule's Law (below):

In conclusion you will need to purchase larger resistors (maybe 10W?) to handle to current running through the resistors. Once you're able to read the stepped down voltage you will be able to easily translate that to % battery life for the LiFePO4 batteries on the float.

Physics and Packing

You had an overall good day today. You woke up and Travis came over around 0830. You bought some things, looked into depth mapping, and contemplated fitting batteries in the float.

You then headed to Travis's around 1000 and bought some more things, and continued work on the things in the above listing.

You then went to the Community Library to take the Physics test, which was a little bit easier than you expected. You felt pretty good on the long answer and a good portion of the multiple choice, but you are not holding your breath as it probably wont be a 5.

You then went to frisbee. It was a very hot practice but you and the team learned a couple plays, worked on handling and scrimmaged a bit.

Finally you went home to pack and prepare for Model UN over the next couple of days. And, once done packing, you sat down to the Bruin's game which unfortunately was not a good game (for the Bruins anyway). You are looking forward to the next few days at Model UN and hope to bring home best delegation with the rest of the US.