I haven't seen a booster box yet that has any sort of smart charging. Most just have a walwart that is rated for about 12-14V and usually an amp or less and you just charge them by time. Even a 12V walwart will eventualy get to about 13.5V when the load drops enough. You could use the charger it came with to charge it then switch to one of these
http://www.harborfreight.com/cpi/cta...emnumber=42292
to keep it at a full charge.
Jeff