You may want to consider one of these: Shorai’s LFX Lithium Iron batteries contain prismatic cells that have no lead, no acid, and don’t create explosive gasses during charge, as traditional lead-acid batteries do. You can mount them anywhere and in any position since their contain no liquid; something that custom bike builders will appreciate. Compared to lead-acid, Shorai LFX Lithium batteries are also extremely light, have much lower self-discharge rate, do not sulfate (i.e. do not degrade while sitting unattended), and are environmentally friendly. If most Lithium Iron batteries available today use round cells—the same found powering power tools—Shorai batteries’ unique construction and the use of rectangular power cells allows them to fit all powersport applications without any modification to your tray or wiring. Shorai adds that while power-tool cells may crank a vehicle successfully, they were not originally intended for the high-current discharges experienced in starter systems. As a result, cranking performance suffers compared to Shorai LFX, and the batteries will wear out more per every start. By contrast, Shorai LFX are the result of years of research and development, and are designed and produced in the company’s own tightly-controlled factory. Shorai LFX have been used in some of the most extreme high-current projects in the world, including autonomous aircraft, boats, and submarines, electromagnetic rail gun research, and more. In short, LFX have been designed from the “ground up’ to be a powersports starter battery with long lifespan and high-performance, under a wide range of temperatures. This sounds like something too good to be true, so Bikernet contacted Shorai to obtain a sample for testing on an air-cooled sport V-twin. When a package from Shorai arrived at our doorstep a few days later, I have to admit that I truly though they had forgotten to place a battery in the box. I understand that these batteries are supposed to be lighter than lead-acid types, but that much lighter was a shock! I opened the box to find the Shorai LFX battery neatly packed and nestled between an assortment of dense foam blocks of various sizes and thicknesses. These are designed to help you fit the battery to your original tray, since the Shorai is likely to be smaller than your stock battery. Next I compared the Shorai battery side by side to the OEM lead-acid unit. The two were close in size but the Shorai was visibly shorter and would not reach the factory positive and negative cables. No problem, I made up the difference by stacking a couple of foam blocks at the bottom of the battery tray and another thin one to keep the battery snug in the tray. Cables were connected next, leaving the negative cable for last as always, and the tray top was snapped into place. I reached for the starter ignition switch and hit the starter… presto! The engine cranked noticeably faster than before and came to life earlier too. Shorai claims that cranking speed is 20 percent faster. I have no tool to confirm it but it feels about right. Here’s a video provided by the manufacturer to demonstrate a typical install on a dirt bike. According to Shorai, LFX batteries last longer than lead acid types. Their research indicates an average of about 2 1/2 to 3 years lifespan for lead-acid. Under the same average usage conditions, they expect Shorai LFX to last roughly double, or 5 to 6 years. Under ideal usage and storage conditions, they expect 8 to 10 years to be achievable. Due to their lack of sulfation and slow-self discharge, Shorai LFX increase battery life most for users who sometimes store their vehicles for weeks or months at a time, and don't want to or can't use a battery tender.