Depends on the Lithium battery manufacturer, however most do not recommend using a battery tender. Some tenders can exceed the maximum 14.5 charging voltage at some point during "tending" and damage the battery.
Lithium batterys do not discharge as fast as a lead acid battery will when left unattended. So in most cases you can just top it off with an approved charger and let her sit.
The best way to recharge a Lithium battery is to balance charge it. Some battery manufacturers will have special chargers that will charge each bank of cells individually. This insures that each cell is getting it's full charge for maximum battery life. A typical lap top battery charger is an example of a balance charger. If you look at a lap top battery you'll notice that it has several connections for each bank of cells.
Lithium batteries may also be wired internially in a way to help promote a more balanced cell charge, when using a standard two wire battery charger as well.
The main thing about Lithium batteries is do not allow them to be discharged below 10.5 volts or over charge them above 14.5 volts, or permanent damage can occur.
As long as you don't have a parasitic draw in the sled that can drain the battery below 10.5 volts Lithium batteries should last a long time.:thumb: