Holding my battery charge on R1150GS

I recently purchased a 2001 R1150GS and don't have access to electrical for hooking up a battery tender. I have a gel battery and would like to know about how long I can expect the battery to hold its charge. The bike's stored in a garage with winter temps inside ranging from 50 down to 30. I'd like to be able to have it last for at least one week

Depends where you are located for one?

A good battery should easily last a week.
Be sure to go for a good ride at higher RPM when you do take it out.
(don't expect to properly recharge idling in city traffic)
If you end up with a problem with battery discharging over a longer period and want to keep it up with no Tender, you can charge up a good car battery at home and backfeed the bike thru the power port. Be sure to observe the correct polarity! +to+ -to-
What you are doing is increasing the capacity of the bikes battery with the car one.
A few cautions:
- Only connect the 2 together when the bikes battery is fully charged or near so (if the bike battery is discharged you may blow the 15A accessory fuse.)
- Don't turn on or try to crank the bike when the car battery is connected.
- Protect the plug on the car battery end when unplugged.
- A basic knowledge of electrical is required

This could also be an option if they have one set up for gel cel battteries

http://batterytender.com/solar.html

I just sent them a message asking about their absorption and float voltages for each model including the solar models. I'll add a post when I get a response.