Hoping it is just a fuse, but it could be worse.
All of our references in this thread were about fusable links, which are different than fuses in the fuse box. Fusable links are segments of wire often buried somewhere in the wiring harness. They’re harder to change than a fuse, but definitely lots cheaper than blown electronics.
Negative to negative is ALWAYS the correct way. This places the two batteries in parallel, keeping the applied voltage at 12VDC when you turn the key to ON no matter what else happens. The car’s starter and the dead battery then become parallel “loads” on the good battery.
In addition, it’s important to connect the positive terminals directly to one another and the negative cable from the jumping battery TO THE CHASSIS GROUND AWAY FROM THE BATTERY. This creates a parallel circuit, but places any potential spark from igniting the hydrogen gasses being emitted from the battery.
also, since the starting system disconnects the chassis ground rather than the HOT wires when the ignition is OFF, it keeps the circuit incomplete until the key is turned ON. That prevents the aforementioned spark from happening.
Realize too that if you connect positive to negative and negative to positive you create a closed loop circuit between the two batteries. You WILL get a spark unless the battery is internally “open”, and if the hydrogen gas doesn’t cause the battery to explode you’ll have a runaway loop tempered only by the damping effect of the dead battery.
Regarding the maintenance man, he sounds like a good guy just trying to help, but without the correct knowledge. Hopefully he’ll have learned from the experience.
I would strongly suspect that a fusible link or two popped when the arc happened. That’s what the links are there for; to save the wiring and electronics when a faux pas happens.
@mountainbike I used to always carry a set of jumper cables and helped many motorist get their cars started in the winter. However, with today’s electronics I won’t do this anymore. I offer to call the AAA if the motorist want it or give them a ride to the nearest garage.
Serious and curious question:
Although today’s vehicles have plenty of electronics, if jumper cables are used properly, what is the concern to either the donor or donee vehicle? Where exactly is the risk?
I used to always carry a set of jumper cables and helped many motorist get their cars started in the winter.
Me too. A couple years ago I pulled in a parking spot at the Pheasant Lane Mall in Nashua NH and this cute little 20 something blond approaches me and said - “Hi sir… Can you Jump me”.
I almost needed the jumper cables to restart my heart.
But alas…she wanted me to jump start her car that I parked next to.
I don’t jump cars anymore either. One never knows if a lawsuit will follow for destroying an ECU that was the problem in the first place.
Joe, the concern is that a current spike will fry something electronic. The circuitry is all protected, but one never knows. I also have the aforementioned concern. Touch the car and you might get blamed for just about anything.
JM asks
" if jumper cables are used properly, what is the concern to either the donor or donee vehicle? Where exactly is the risk?"
I zapped an alternator diode on my early 90’s Corolla doing a favor and jumping my neighbor’s ancient and decrepit Ford sedan. Apparently the Ford’s battery was so dead, the poor Corolla’s alternator just didn’t have the punch to both charge his dead battery and attempt to crank his starter motor. That was it for me on the jump-starting thing. I’m happy to call AAA or a tow truck, and keep a cell phone in the car with those number pre-programmed. Usually when I offer to phone a tow truck, the owner needing a jump will wave at me to go away … lol …