That is probably for nicd's right? I've read many places that you should not store nimh w/out a charge.
I am considering getting a battery tray, but I too am unsure how specifically to use it. After running your car if you have 3300mah cells, you might still have some significant juice left - should you first use a 20amp bulb discharger to drain most of it? Or is it okay to drain what's left on a discharge tray that uses leds? I wasn't sure leds would have enough of an amperage draw to drain the batts.
After that though, it's my understanding - if you are using nimhs - you should immediately remove the batts from the tray when the lights go out. Then - after it cools - immediately recharge it. Recharge 1/3 if you are storing for less than a week - and 1/2 if storing it longer.
But what do I know?