Info wanted for large scale project

Hi All
I seek your input and advise.

Aside from flying my regular 15 meter factory glider, I also built
gliders as a hobby in the cold Canadian Winters. I am now on
my third project and I wish to incorporate a retrieve system in this
one.

My aim are modest, I require a single 15 KW motor,
combined with a controller and a set of batteries to operate
the system safely.

The demand on the system is as follows:

1)  It needs to provide "max continues power" of 15 KW  for 15 minutes
or more

2) The controller should be  matched to the motor, unless they are
universal units.

3) The battery packs should be reliable and safe. Not necessarily have
the
    highest power density. They should not need any special attention
during
    operation and should hold there charge for at least a few days.
4) A low RPM of around 2000-3000 would be desirable.
This would eliminate a reduction drive.

All your comments are welcome, if they can contribute to this subject.

I have seen the  Predator 37 by Plettenberg max 15 KW
I am not sure if that would be the right solution for me as a larger
prop would give me more thrust.

The only data from Plattenberg:
 47,0 volts  308,0 amps  6300 rmp
The propeller CFK  28,5x12  RASA Kl. 3Bl

Thanks and Regards
Udo