[Yak] Electrifying a Family Tandem

[Carlos Chavez]

My young niece is now the stoker on our family tandem.  Needless to say, 
she is not yet up to providing much power output.

Has anyone added one of the front wheel electric motor systems to an 
FT?  It seems like it would be an easy project.  I am asking for any 
recommendations for power (watts) and battery voltages (24-36-48?), and 
of course brands.  Would also welcome any discussion on types of batteries.

Mostly i would like some assurance we can get back to our starting 
point, so I am looking for a little boost on hills and some sustained 
power if we are too far from home.