05/08/2016 at 01:34 •
UPDATE: 05/30/2016- I'll have to scrap the 18650 battery pack idea. The best way to build battery packs is to find a battery supplier in which you can customize packaging and chemistry of the cells. This is too specific for my DIY system and I'm getting lost in the details. Building a battery pack has taken more time and energy (get it?) than converting the motorcycle. I'm stepping back from the custom pack idea and designing the rest of the system to be more versatile and battery agnostic.
Choosing a battery system
Over at the elMoto.net forum, I contemplated battery options. CALB-style LiFeO4 prismatic batteries were all the rage 4 - 6 years ago but in the past 2 - 3 years it's been all about Nissan Leaf battery modules. HybridAutoCenter.com has a great article on these modules and they can be acquired relatively cheaply compared to other chemistry. While the Nissan Leaf module may be the bees knees in terms of cost, quantity, price per kWh it does rely directly on Nissan (and usually wrecked vehicles) as a supplier of these cells.
18650 Lithium Ion cells
18650 cells are usually 3.7v 2500mAh batteries that can be configured into series packs for more output voltage and parallel for a higher current rate. I have recently negotiated a deal for 1,650 cells from battery packs built by Tesla Motors. This is approximately 15,675 Wh of energy in 170lbs of cells. Compare this to the 5,760 Wh of energy I currently have using 174lbs of lead-acid batteries. Because the individual cells are self-contained and smaller it will be easier to build battery packs of different shapes to fit the curves of the motorcycle build
I envision standard modules of 3p16s cells arranged in "Bricks". Each brick is approximately a 12v 40Ah module with an integrated BMS, temp sensor, and etc. This will allow me to configure larger packs easily from smaller bricks. Once I get the EV Box DisplayBox integrated (speed, voltage, and amp functions for now) I will work on the details of the Brick architecture.---------- more ----------
- Each "half-brick" will have a self-contained BMS (qty 3), pack fuse, temp sensors, etc.
- To make a whole brick we parallel a special half brick w/o a BMS. Each brick is essentially a 12v 40Ah battery equivalent.
- Each brick in self-contained enclosure that can snap/bolt in place. (Like a bottle enclosure)
- Motorcycle: 6 "half-brick" slots.
- Lawn mower (push): 3 half-brick slots.
- Lawn mower (ride): 4 brick
- Go-Kart: 2 half bricks
- Car Conversion: 12 whole bricks (or more)
Build a battery cage assembly that resembles mail slots. The slots are already prewired for the series/parallel configurations needed on each brick. All we have to do is insert brick into slot and secure it. DIY Tesla PowerWall? Batteries for camping trip? e-Bike batteries for a quick trail run? Snap some bricks in and/or easily carry a few extras.
Actual Tesla-built batteries
I purchased a set of 5 battery packs designed and built by Tesla Motors for an electric smart car. There are 330 2700mAh cells in each pack configured for 15S22P configuration. The gamble was that the cells are mounted in the packs loosely without any adhesive. After communicating with the vendor he tore open a pack and it looked clear and easy to disassemble.
Once the packs were in hand, however, the were securely epoxied in at the top and bottom of the casing. The case appeared to have a seam that could be parted, but the tops and bottoms of each cell was attached with a hard black epoxy to the outer casing. These cells are next to impossible to separate without damage. It's back to the drawing board.
UPDATE: 05/30/2016- I'll have to scrap the 18650 battery pack idea. The best way to build battery packs is to find a battery supplier in which you can customize packaging and chemistry. This is too specific for my DIY system and I'm getting lost in the details. Building a battery pack has taken more time and energy (get it?) than converting the motorcycle. I'm stepping back from the custom pack idea and designing the rest of the system to be more versatile and battery agnostic.
TODO: Rewrite and add more formal details of the battery packs.
TODO: Get the details of the vehicle they were removed from.
TODO: Decide to keep or scrap the modular features. Link Zero motorcycle webcast as reference. If scrap, spinoff modular idea in a separte log for future revision.
TODO: Link photos to the Google Photos album.
TODO: Edit uploaded photos with labels and arrows (and unicorns)
TODO: Add purpose (or objective) section as top header of page.
05/02/2016 at 19:34 •
Bright and Sunny
...was not the weather forecast today. It was supposed to rain until Tuesday. The past 6 days it has been cold, cloudy, rainy, and miserable. Today was supposed to be yesterday's cousin, but somehow the sun has reared it's head.
Today's objective was to catch up on documentation and updates for the motorcycle conversion project. I have tons of pictures and envelope drawings, video snippets here and there. I wanted to use this site to capture that data as I move and then maybe migrate to my own website? Company blog? :)
I can't sit in my wife's book nook drinking Spring hot chocolate (just like regular hot chocolate except you also ponder deeply why it's so cold in Spring) while coding and updating what feels like "the paperwork". The sun (and awful humidity) is staring at me right now saying, "build".
Time to ride.
05/02/2016 at 16:41 •
Current development work has begun on the EVBox and the code is progressing along. It has been cold and raining all week so code developement indoors was the best move. The electric motorcycle still needs the following items complete:
- Construct upper battery cage
- insulate battery terminals
- Battery cablling
- Circuit protection (no fuses are installed anywhere, yikes!)
- Install DisplayBox mounts
I have accidentally shorted the battery terminals twice now. The second time if boiled the solder in the 2AWG copper lug and sprayed it. This was only 24v and it was highly dangerous so circuit protection and insulation is my FIRST priority.
There is a chance I am in the market to upgrade to Lithium chemistry for my battery pack. Not to count my eggs before they hatch, I'll just say that Nissan Leaf cells or a custom Tesla 18650 battery pack is currently in the works.
Next, there are three things to be tackled this week:
- Update bike wiring
- Update battery vendors for chemistry upgrade
- Complete TestBox
- Complete DashBox