I've used a battery tender on my previous Kawasaki Concours as well as the Voyager I have now with no issues. As a matter of fact, if you want to try and hurt your ECU(s), improper jumping to a car system is a great way to do it.
If you are interested in batteries, the Battery Tender website is an excellent source of information. Since the battery is a crucial element in any vehicle electrical system, it is worthwhile knowing how to keep them working properly.
I always laugh at the used motorcycle ads that say "runs great, but just needs a battery".
2012 Voyager ABS
Custom Made Trim Covering Bag Frames
LED Strip Lights on Custom Trim
Conspicuity Flicker on LEDs in Tail Light Mode
Flashing Brake Lights on LEDs
Kawasaki Bag Guards
Longer Kickstand from 2000 Nomad
Alaskan Sheepskin Butt Pad on Standard Seat
12" Clear Windshield for Summer
16" Windshield for Winter
Kuryakan Longhorn Highway Pegs
Also Drive a Restored 1980 Goldwing Standard