Sunday, January 19, 2014

Batteries, A Lack of Aluminum, and Mystery Boxes

Last time on ScooterQuest™(or rather, what I did during winter break), I finished assembling the 10S2P pack. 

HDPE on the work area helps prevent accidental shorts.

Recycled from two 6S2P packs floating around MITERS, it was originally wrapped in some forearm-sized heatshrink that was at one point cut in two and then rewrapped in electrical tape. Welp. 

Of course, the whole idea of having an uninsulated pack of LiFEPO4 cells crossed my mind well before I started, so I opted to heatshrink the thing in PET. 

The cheapest source being my preferred $0.99 beverage above. Note that the 20 oz. variety appears to be the perfect size for 2P packs. Further, starting with plastic that's already near diameter of your pack will yield the best results.

It's also important to heat the plastic evenly and to assume shrinkage at the edges by at least 1cm as to avoid gaps in your insulation. 

Following the advice of Charles, I made sure to route the balance leads on the side of the pack as to avoid a burny death. 

A wheel well-type object was folded then attached to the bottom panel of the scooter to keep debris from flying into the electronics. Given that it isn't a structural feature, it was made out of sheet aluminum and attached with screws to the bottom panel. 

Speaking of missing components, I quickly realized that I needed more aluminum to build the caddy assembly. 

Since the entire thing would have to be milled, I opted to save myself the trouble and do it on the CNC. This meant modeling the parts in solidworks.

The hella switch and battery connection have been integrated into the front panel for easy access. 

In other news, I recently came across this on kickstarter. 

Their instructable revealed the inner workings.

An ATtiny that turns on a few LEDs and plays noises when activated by a crude, but effective capacitive touch plate.

Oh, and it's powered by a USB wall charger with wires soldered to the AC prongs.


Don't get me wrong: it's a fairly nice object, but there were a few key design qualms that kept me from purchasing said object:
  • Several box joints are used to keep the lid and bottom together, which, in the event that the joint fails, would cause the thing to plop out of its enclosure and expose an uninsulated AC line. 
  • It's too small to be a hanging lamp, yet too large to sit on a desk without taking up too much space.
  • It's too dim a light source to justify as a functional lamp
  • Aesthetically, the joint construction lends itself to having jagged lines. 
  • The silkscreen only looks good when the thing is on. 
  • For what's inside, $49.95 is ridiculous. 
And so, I spent the following evening sourcing parts and making a model in solidworks.

The question mark spaces will be filled with black or smoky acrylic. 

The current cube configuration is 3' to a side, making it a little bigger than a tree ornament (heck, it could probably be one too). 

Its purpose is to comfortably fit on a desk as an ornament providing a bit of extra light when needed.

To be continued...

No comments:

Post a Comment