Im going to start some experiments with some smaller lipo packs… to see what sort of cooling I can achieve with a few small cells.. The only problem I foresee is expansion… Lipo cells like to change in size… ALL battery’s give off gases while charging etc… So ventilation is a must… Modern PC’s use “Heat Pipes” http://en.wikipedia.org/wiki/Heat_pipe At the hot interface within a heat pipe, which is typically at a very low pressure, a liquid in contact with a thermally conductive solid surface turns into a vapor by absorbing the heat of that surface. The vapor condenses back into a liquid at the cold interface, releasing the latent heat. The liquid then returns to the hot interface through either capillary action or gravity action where it evaporates once more and repeats the cycle. In addition, the internal pressure of the heat pipe can be set or adjusted to facilitate the phase change depending on the demands of the working conditions of the thermally managed system. An aluminium or stainless steel plate… with a lipo cell on each side… connected to a central heat pipe! J think a stack of those placed side by side… in a stack of cells and plates.. with the central tube running up the middle of the cells… From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of Cliff Redus Carsten A four fold increase in range for your application is a strong motivation for following the lithium battery technology. My hope is that with the resurgence of the electric car and the R&D that is being funded in battery technology, the Psub world will get some next generation batteries that are affordable with the bugs worked out. Sgt.Peppers would make a nice test bed for Lipos. Cliff |