Jump start SNAFU

Yeah, So I was at Lowes today. An older gentlemen had the hood up on his Cadillac.

I offered to help. He got his jumper cables out of trunk and connected the clamps to his battery. I connected the other clamps to my battery, and got a big spark.

Yeah, nothing happened. Even after I started my car.

So I am looking at the clamps: The end of the cables connected to my car had 2 red sleeves....(!?)

Got that figured out, swapped clamps, and his car started.

I showed him the FU, and he just shrugged....

Question to the hive: Did I fry my alternator? I was lectured in the bad old days that a cross connect would fry the alternator as a minimum. My car is running fine.

I'm feelin' pretty stupid right now...go easy..(grin)

Rog

If it's charging the battery then you got away with it. Otherwise you may be looking at a fusable link or an alternator.

I hooked the boat battery up to the charger backwards once when I was younger. Big sparks, but everything still worked as it should when I realized and fixed my mistake.

I did it once too. Jumper cables got hot fast as you basically have a complete circuit between two batteries, so current just goes in a circle. Luckily, the current mostly stays in that circle, and the battery with the lower voltage actually kinda controls the situation.

Your alternator probably did peg to full output (whatever it can do max at idle, which may not be a lot) to try to keep up with the rate the battery was discharging, but it is designed to have a max output at a safe level.

So you were depleting your battery quickly, heating up some copper, and mostly scaring yourself.

Let this be a lesson to you: When jumping off someone, YOU AND YOU ALONE ALWAYS HOOK UP BOTH ENDS OF THE CABLES. NEVER ASSUME THE OTHER GUY KNOWS WHAT THE berkeley HE IS DOING.

We were cleaning my dads garage out and my brother found some cheap cables that had 2 cables each with oppisite color ends on the ends. What the heck - we tossed into the garbage.

The crappy low gauge wire in the cheap cables prevented damaging levels of current from flowing. Always triple check your connections when using jumper cables, a run of the mill group 35 car battery contains something like 7 hand grenades worth of energy.

I hooked up a jump box to a Range Rover backwards in the CarMax showroom once, sparked like crazy and scared the hell out of me. The only good thing about that story is it was on a Range Rover, so if anything got fried you wouldn't be able to tell.

The advantage of lead-acid batteries is that they're pretty dang forgiving. If the car is running OK and charging the battery, you're fine.

FYI, the reason telecoms and big datacenters still use VRLA (Valve-regulated Lead Acid) batteries over more "efficient" lithium-ion batteries to back up their equipment is because of how much less maintenance is required on the old lead-acid behemoths.

I learned a somewhat similar lesson back in 1989-1990 or so. I offered to help someone in the parking lot of the apartment complex we lived in at the time. I hooked everything up, started my car then told the lady to try hers. It started up and she jumped out, grabbed both cables off her car and tossed them onto the ground. Of course they were still connected to my car and of course they shorted together as they bounced around on the asphalt. My car seemed ok, but about a month later I had to get a new starter. Then a month after that I had to get a new alternator. Then it was realized that some of the wires in my harness were pretty well burnt and melted. Me trying to be helpful cost me several hundred dollars I did not have at the time and left me with a car that had intermittent electrical gremlins. I ended up trading that car in for the first new car I bought, a 1991 Mercury Tracer wagon. I remember my wife and I watching through the dealership window when the guy went out to look at our car for trade in value and we were both prying it would start since it sometimes worked and sometimes left us stranded. It started and the deal was on. If anyone bought a 1986 (or maybe 87?) black Chevy Spectrum 4 door in Central Florida in the early 90's that was a POS, I apologize.

As I drove into my garage, I see my neighbor across the street looking for a jump. I got my starter pack and we started his car. I told him, I never jump from my car, relating back to what Dr.Hess said.

Back in '93 I left my lights on one night while 600 miles from base and visiting relatives in NY. Dude come out in the morning offering to be helpful he holds up his jumper cables. I hook up my end and I look at him and say "you know what you're doing?" he shakes the red and says positive and shakes the black and says negative. Great, I got a guy who knows his business. When I try to start my car ("91 Eclipse btw), nothing happens so I get out to look and find that he had connected his end backwards. I'd blown the main (80 amp) fuse which is not available in Westchester County on a Sunday. Got one on Monday and scampered back to base a day late. The other casualty was the stereo, it died in the encounter leaving a very long quiet time down I-95.

tldr: lay eyes on everything yourself, even when the other says he knows what he's doing.

I have a question. The battery in my 64 Spitfire is positive ground. The people in my Brit Car club say its no problem to jump it from a car with a negative ground battery. What say ye?

In reply to spitfirebill:
Power is still going from positive to negative, so as long as you match the polarity of the cables you should be OK. The difference is the path from the load to the battery.

but on old brit (or old anything really) check to make sure you're not trying to jump a 6 volt battery with a 12 volt system.

This is probably the most useful thing I've purchased lately. Jump start your friend, and charge your phone.

12000MAH 500A battery pack

Sky_Render wrote: FYI, the reason telecoms and big datacenters still use VRLA (Valve-regulated Lead Acid) batteries over more "efficient" lithium-ion batteries to back up their equipment is because of how much less maintenance is required on the old lead-acid behemoths.

Also the real value of lithium-ion batteries is the specific energy -- for a given weight of battery, LIon will store 2-5x as much energy as lead-acid. This is a big deal if you're carrying it around in your pocket all the time, not so much if it's just going to sit in an equipment rack and the only time it gets moved is when the installation guys are humping it up the stairs.

It didn't happen in relation to a jump start, but lemmie tell ya, when a battery explodes, it's a HUGE, SCARY thing. We were lucky nobody got hurt.