QUOTE(mepstein @ Aug 27 2019, 12:45 PM)

I plan on using a 4 pound lithium battery so may not bother with the tray at all.
@mepstein Be careful with the Lithium ion battery. Do your research, charge carefully & with charger designed for Li-ion. All Li-ion are a fire risk, especially so if they don't have a built in battery management system (BMS).
Used plenty on race cars but they haven't made prime time on automotive for good reason. Obviously, excluding EV's which have a dedicated BMS and yet EV's still go up every now and again, along with cell phones, Laptops, Vaping devices, etc.
Also be aware that Li-ion doesn't like to be stored at full charge for extended periods. Preferred storage is at 50% state of charge.