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Old Streetfighter Motorcycle Forum Post 01-17-2020, 03:36 AM   #10
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Default Re: 2009 Buell XB12Scg custom II

The next step was pretty challenging. I had to find place and accommodate the rest of the electrical system components: battery, fuses, relays, flasher, tilt sensor and ECM unit.

I already assumed the place for this stuff is gong to by space in the airbox. So to figure out how I can place all this stuff inside the airbox I had to reverse engineer the arbox parts and all the electrical components nd create CAD models for them. My plan was to minimize modifications of the airbox and build a frame which will hold all the electrical components so I can easily move all the components from the airbox just removing the frame in case if I will need to get under the airbox.

So here is real part vs 3D scanned object vs reverse engendered CAD model

And here is what the airbox on motorcycle

After this work had been done I had to figure out what is the maximum battery size I will be able to squeeze inside this space, and most impotently if this battery is capable to crank big V-Twin engine.

So I bought and tested two batteries - Antigravity AG-SC-1 4 cells lithium battery and Antigravity AG-801 8 cells lithium battery. It seems like Antigravity makes the smallest motorcycle battery on the market, so I did not have much choice. They do not install battery management boards on 4 cells and 8 cells batteries though, so it is more dangerous stuff and requires more attention.

After some riding tests I found that both batteries are capable to crank the engine but 4 cells battery makes it really slow and it really struggles. 8 cells battery cranks engine much better but even for 8 cells battery cranking this engine is tough task. You can see on the video in my 1st post how it struggles with compression bump. But anyway, there is no space in the airbox for something bigger, and I was not pleased with 4 cells battery so my choice was the Antigravity AG-801 8 cells lithium battery

I also had to figure out how to mount power management components: fuses, relays and flasher. the stockk Buell fuse box is pretty big and would not fit the airbox. I needed really compact solution. After some searching in Internet I found it. Littlefuse company makes nice compact, dense packed configurable fuses and relay modules for MINI fuses and MICRO relays for automotive industry. You can assemble the power management block with the shape you want like a Lego. They have catalog with different blocks, different crimping terminals for different wire gauges and another necessary parts to configure and assemble power block you want.

After figuring out how many fuses and relays I need I found necessary Littlefuse parts and parts numbers in their catalog and bought it online on DigiKey and Mouser.

To make long story short here is the final layout of the airbox power management components.

As you can see all the components are mounted on the chassis so you can easily move them out the way if you will need to. This chassis is going to be assembled from plastic parts printed on FDM 3D printer from ABS plastic. ABS is pretty heat resistant plastic and can stay in that area without warping or melting under heat from the engine.

Here is the power block assembled from small LittleFuse blocks with fuses, relays and flasher. Those small square blocks can be differently oriented and attached to each other to maintain the shape and components allocation you want.

My power management block has a few extra fuses and relays in addition to the existing Buell XB fuses and relays. Those extra fuses and relays are for alarm system, Motogadget Motoscope and Motosign cluster and power outlets. There are some LEDs lights in the Motogadget Motosign cluster dedicated for Low Fuell Light, Check Engine Light and Neutral Gear Light. Those lights in Motogadget Motosign gauge can not be connected to the Buell XB electric system directly to the signal wires, the LEDs need to be connected to the relays and relays are controlled by those signals wires. You can find more technical details about how the Motoscope Motosign LEDs lights connected to the motorcycle electrical system through the relays here

I also eliminated Auxiliary relay from the motorcycle harness because of I do not use this relay and there is no space for this relay anyway. But on Buell XB this Auxiliary relay is controlled by ECM and if you will remove it the ECM will lit Check Engine Light with error. To eliminate this error you have to change EPPROM file on ECM. Here are more details about how to disable Auxiliary relay on Buell XB to prevent ECM error message
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