Here is a rather simple construction that can get you out of trouble if your battery is flat while you are at the pits.
You need a battery case box that can hold ten AA sized batteries and a suitable connector for your wiring loom. Batteries should be rechargeable but in case of emergency any type can be used.
The output will be about 14-16V DC depending on the batteries being used and will have a capacity of more than 2Ah at 12V DC.
Dimensions of the battery pack are 58x78x30mm and total weight including the cells is 280gr.
Great for :
* backup battery for total loss ignition systems
* run devices on the pits, like ignition strobe timing light etc.
* easier accessible and cheaper alternative for the stock Yamaha TZ250 battery pack