Modern Vespa

I accidentally left the key turned and my battery dies. My husband hooked the battery tender up to my Lexus, and it blew a fuse.

The only way we could jump the battery was from his Harley (which by the sounds of all the grumbling must have been a real pain).

My son says he jumps his bike from his auto all the time... any answers?

should not be a problem, you do not start the car as there is plenty of amps in the car battery.

load is too high. don't do it with the car on. you can do it if the car is off. Otherwise, you'll learn what that fuse cage on your bike is for, and which fuses are spare and which aren't

I honestly can't rememeber if he had the Lexus running or not... there was too mush complaining... I am sure to remember to turn the key off from now on!!!

How did he hook the battery tender up to the Lexus? The tender itself plugs into a wall socket and then the leads connect to your battery, with either copper clamps or ring terminals and a quick disconnect plug.

The wording of the original post is extremely awkward and confusing.

After reading it several times, I gather that the OP's husband tried to start the scooter from the Lexus using permanently installed Battery Tender leads on the scooter battery to make the connection from the jumper cables (the original post makes it sound as though he tried to use the Battery Tender charger on the Lexus!). Trying to jump start the scooter via the Battery Tender leads will, of course, blow the fuse in the lead as the starting current far exceeds 7 amps.

Jump starting a scooter from any car is no problem, as long as you connect the jumper cables directly to the scooter battery (which, of course involves removing the battery cover, which is probably the hassle the OP's husband was trying to avoid). No need to have the car engine running, and it is probably safer for the electronics all around if it isn't.

We'll probably get clarification from the OP after the garage fire has been put out.

SDG