http://antigravitybatteries.comFor those custom applications where you need a small & powerful battery that can be mounted almost anywhere & hidden from view. This company offers batteries from 6V to 16V plus they have a model for the FT500 Ascot. I did not see a model listed for the VT500 Ascot, but I imagine that there is one that would work. It may require some modification to the battery holder.
I ordered one for my FT500/CBR600 Hybrid bike. It measures 4.5″ Long x 3.12″ Deep x 4.25″ High to the top of the terminals, and only weighs 2lbs 4oz !!!
These batteries are not inexpensive, but they are supposed to last a long time as long as they are treated properly & kept on a battery tender during the off season. One guy that I know of, has one of these batteries & it has now been transferred over to his third bike! They are available through Amazon.com, plus I know a dealer that will sell them for a bit less than that. Just let me know if you are interested & I will forward you his info.
Good luck
J.