Thursday, April 30, 2009


It's been a while since my last post, but it's not for a lack of working. After painting the battery tray, I reassembled the bike and started in on the wiring. With so many batteries, this is a huge undertaking. The picture above shows all of the ancillary bits that connect between the battery pack and the motor. At the top is a high current, keyed switch. I added this switch in after deciding the contactor by itself was insufficient. The contactor is to the right of the switch, with the metal band around it. It is an electrical switch, or solenoid, that is actuated by the motorcycle's ignition switch. As recommended, there is a 1000 ohm resistor across the main contacts. I found that this resistor got hot when the contactor is open (whenever the bike is turned off). To the right of the contactor is the main fuse. Below all that is the controller, an Alltrax AXE-7234. This controller is pretty sophisti-ma-cated, allowing you to program a number of parameters on your computer.

Thursday, April 16, 2009

Lead Junkie

A typical electric motorcycle has 4 to 8 batteries. My bike has 18 batteries! The battery pack that I am building is probably less efficient in size, weight, and capacity than a similar pack with fewer cells, but what I lose in efficiency, I gain in its ability to fit into small spaces.
When postimg on , I need a name for my bike so I've decided to call this bike Lead Junkie. You know, because the batteries are made of lead, and it can't seem to get enough of them. Pretty clever, right?

Without giving it much thought, my plan was to connect the batteries in a series-parallel layout, which is shown in the image below.

After doing some reading on the Internet, I've decided that a Parallel-Series connection is more desirable. The resulting battery pack is the same (72V, 68Ahr), but the effect on individual batteries is different. I'll try to explain.

One issue with connecting batteries in series is that the voltage of a single battery can drop, dropping the entire pack voltage and putting a higher load on the other 5 batteries. If the batteries are paralleled first, then the other two paralleled batteries can maintain the pack voltage, while only increasing the load on 2 batteries.
Perpabst I'm not explaining this very well, so suffice it to say that I think the latter configuration is better, and this is how I will test my pack. From a physical wiring perspective, this config requires more wire and more connections. I have increased the gauge of my wire to 8 AWG for the parallel connections and 4 AWG for the series.

Monday, April 13, 2009

Another Day, Another Tray

This tray holds 4 of the smaller B&B batteries. It will be mounted underneath the seat where the engine's airbox and battery box were originally located. When installed, there's just enough room on top of this tray to hold the DC to DC converter (see below). This converter takes the 72 Volts from the battery pack and converts it to the 12 Volts that is required to run the motorcycle's accessories.

Sunday, April 12, 2009

Paint Shop

Today, I added a second battery tray to the to the upper front of my main tray. I also put in diagonal supports in the bottom front corners. Previously, I wrote about adding lateral stiffeners, but I did not put these in. If I find that I need them, I'll add them in later.

Saturday, April 11, 2009

Major Milestone

I felt like I finally made some progress last night, when I completed enough of the battery tray to mount it with batteries on the bike. This image shows how the 6 Optima batteries are arranged around the motor. As an unexpected bonus, there is enough space above the front stack to position 2 of the B&B batteries. Very cool.
The battery tray feels stiff when in place, except in the lateral direction. I am going to weld some cross members diagonally across the front face of the tray to stiffen it up in this direction. Also. I'm concerned about fatigue under the vibration environment of the motorcycle. I think regular inspection of the weld joints is my only solution to know if fatigue becomes an issue. The quality of some I my weld joints is suspect, so I'll be going over them again.

Friday, April 10, 2009

I Put Some Gas in my Car and I'm Ready to Go Go Go

I had previously done some work on the gas tank before I was writing on my blog. The tank is obviously no longer needed to hold gas, but has to remain on the bike for aesthetics. Inside of the tank is a lot of wasted space, so I cut it in half to put stuff inside. On my particular bike, the tank is partially covered by the front fairing. This produces a recess in the bottom half of the tank and was the perfect place to make the cut.
The first picture shows the bottom half of the tank sitting in position, with 4 batteries stored inside. The top half of the tank is sitting where the seat should be. I still need to add a latch and hinge to hold the two pieces together. This has to be designed so the tank doesn't fly open while I'm riding and also has to be strong enough to take the load from my leaning on it.
The second picture has the top and bottom of the tank in position. I put some edge guard around the cut edges of the top piece so there are no sharp edges.

Wednesday, April 8, 2009

Parts For Sale

I am selling these extra parts on Craigslist. They have been pulled from my 1993 Kawasaki EX250 Ninja and are no longer needed for my electric conversion.

Engine & Carburetors

Cooling System

Exhaust System

Tachometer & Oil Gauge

Air Box

Ignition Coils & Voltage Regulator


This picture shows the beginnings of the changes I'm making to my electric motorcycle instrument panel. The center pod housed the engine tachometer, which I no longer need. I have replaced it with 3 digital meters for monitoring the electric motorcycle's performance. The red one on top is the system voltage meter that I've shown before. The green meter with the triple 8s is a amp or current meter. Below that, is a temperature gauge. This gauge is fitted with a probe that I will attach to the motor housing. The 3 digital gauges are panel mounted on a sheet of plastic that has been cut to size and spray painted flat black. When the bike is running, the gauges will hopefully be the only thing you notice.
The lower right pod was the engine oil temperature gauge. I have replaced this with a clock, something this bike was sorely missing. The "clock" is actually a pocketwatch that happened to fit right into this space. Above the clock are 4 dummy lights. 2 of these lights are unused on the electric conversion and will be replaced with battery charging status lights.

On a side note, I've gone through half a dozen iPhone apps, looking for the best way to post on my blog. This post is sent via Blogpress, which may be my final solution.