RE: Wall charger to trickle charger
I'll second the TME Auto Trickle Adapter suggested by Danh4, but even better is their
[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&P=SM&I=LXHS77]TME ChargeMinder[/link] for only 5 bucks more.
You can select different charge times up to 16 hrs before going into trickle, so it's also good for drills and such whose chargers give out a faster charge.
I've been using these on my Nimhs and haven't seen a problem.