I think you have to build one..or use a 14V wall wart to trickle charge it.
This (DIY charger link below) seems better because it would be easy to build and its pretty flexible - so if you decide to build it and use it for a bench charger you can set it to whatever size battery you need to charge. Just need to replace the 12V transformer with a 16V which should be easy to source.
This also is a very small charger so it would easy fit into a case that can be mounted near the battery for onboard charging.
http://www.aaroncake.net/circuits/charger2.asp?