Join Date: Sep 2012
Location: St. Clair Shores, MI, USA
Re: Portable Jump Starter for the LT
I'm not sure I'm at all convinced your "battery is good".
It may be "in spec" for summer use, but it clearly isn't flipping the engine over properly in cold weather. That means either 1) your battery is weak in the cold. 2) LT's draw more power than can be provided by a prime motorcycle battery of the size that will fit in an LT or 3) your LT's starter is weak.
I'd suggest you have your battery cold-load tested -- at 10F or so. Batteries are funky things...I've seen some bizarre failures. Plus...motorcycles are not as often run at 10F as they are at 50F, so a "good" battery may be incapable of doing the job...you may need a "great" battery.
An external jump-pack is based on the exact same technology as your main battery is, so IF your battery is good, it is unlikely a jump pack will help much, as it will be suffering from the exact same cold. It's primary benefit would be a little extra current, MAYBE that would be enough to get you going. Realistically, jump-pack batteries usually live a much harder life than main batteries, they are charged more rarely, they are discharged and then not immediately recharged, etc, so there's a strong probability that it may not help you when you need it.
(Don't get me wrong, I *love* good jump-packs, made a lot of friends and got a few free meals from 'em, but buying a good one these days is not easy, and you need to treat them well)
You can NOT hook up a jump-pack though an accessory outlet for starting the bike -- when you crank the engine, it will draw more amps than the outlet's fuse and wiring will take -- hopefully the fuse blows before the wiring melts. I've used jump-packs attached to the accessory outlet when a car had a battery SO dead that it couldn't keep the engine running when the the car was in reverse with the brakes on (slow engine speed, four light filaments going)...in that case, I started the car by jumping the battery, then attached the jump pack via the cigarette lighter charging cord to keep the engine running as I followed the guy to the battery store...but do NOT try to start via the accessory plug!!
IF your starter is healthy, and LT's just can't start off the stock-size battery in perfect health (haven't owned mine in 10F weather yet, and honestly don't plan on starting it at that temp), maybe you need to put a small car battery in the top-case, and wire it down to where the battery was. Not to be done by the electrically challenged -- lead acid batteries store a lot of power, any flaw in the wiring, either immediately or after a few thousand miles of vibration, can result in amazing failures, often involving molten plastic, metal and/or spraying acid.