For the cost of one or two packs for your plane, one of these power packs can
recharge you packs by running your DC charger. Yyou can carry them on a bike,
or the lighter ones could be carried in a back-pack with the rest of your field equipment.

They are simple to use. It is just like using your car's cig lighter plug or
clips on the car's battery. You a 12 volt DC charger and charge your
batteries at the field. They can also
be used at the house so you don't need a DC and an AC charger. I use one in my
shop for that purpose.

Here is the one that sears sells:
http://www.sears.com/sr/javasr/produ...id=02871472000

Target sells this one:
http://www.target.com/gp/detail.html...sin=B0002INUMK

If there is no plug for your plane's battery charger and it doesn't have
clips, adding plug a port to one of these packs would involve an adapter like
this. Easy
http://www.radioshack.com/product.as...%5Fid=270-1527

I am able to bring my car to the field so I don't need this for field
charging, but I use one of the larger jumper packs, similar to this one, in my
shop to power my 12V chargers. I actually used it the other day to jump start
my neighbor's car. It is cheaper and more versatile than an AC/DC charger or a
12 V power supply that would need to be plugged in.

More
http://www.wattflyer.com/forums/showthread.php?t=1933