Here is my experience, My Kubota sometimes sat for over a month in the winter without starting, without a maintainer of any kind and no problems, I understand the desire for the maintainer, and think it a good idea. I have run the maintainer for my garden tractor for several years, just because it will sit for months without starting. My thoughts about the maintainer are this: If the new battery is in good condition, all you are making up for is the internal losses in the battery. In other words if there is no electronics/electrical externaly drawing down the battery, then the only losses is the internal resistance leakage currents inside the battery that eventually discharges them. These internal losses are very small, but do add up over a period of time. I would think a small 1.5 watt maintainer would be plenty to keep up any size tractor battery from internal losses even during the cold/dark days of winter. On the other hand, keep in mind that a larger solar panel can pump out more current, and these panels are unregulated unless you install a charge controller and you run some risk of "cooking" your battery with the voltage and current the solar panel can generate over time. The battery will drop the open circuit voltage of the solar panel (which can exceed 24V) to a safe level until the battery reaches full charge, then the voltage will continue to float up and up, and the battery will outgas hydrogen and oxygen. So I would not be sticking a larger panel than a 1.5 on a battery without a charge controller. Even one of those in summertime with a lot of bright days and high sun angles might not be a good idea to leave on all the time. Also it has registered in my brain now that I have a tractor with actual Electronics on-board not just electrical things, that connecting even the 1.5 watt controller (still a very high open circuit voltage) without any type of voltage regulation on it may not be a good idea. Yes the battery will drop that high voltage very quickly (milliseconds?) but still it is a transient high voltage spike I am introducing into the electrical system for a small amount of time. Microprocessors do not like high voltage spikes. and have been know to lock up, roll over and die etc. Use the maintainer with caution, and one with a charge controller might be a good idea.. Not to pee on your project, but to caution you.
James K0UA
