Any electricity gurus here? Odd question.

[Turbo6Smackdown]

I'm sure there's at least 10 professional electrician around here, so here goes an odd question. Tried to jump a friends car with my jumper cables, and it would just not take a charge. That car sat there charging for 30 straight minutes. Nothing. I have the good grade cables ya get from any local auto store. They're pretty thick, and long as well. I know you're not supposed to do this but, when they were hooked up to my battery, I touched the two clamps together to see if there was a spark, to see if these cables weren't shorted out somewhere. There was a spark. Stuck 'em back on, and nothin. No charge whatsoever. My friend then used a slightly shorter pair of like cables, and the car charged in about 4 minutes, and started right up. I threw a ohm meter on my cables when I got home, and they were fine. What's up on that.

My cables aren't shorted. Why did another set of cables that were just 4' shorter charge the car right up. What am I missing?

 

[Phoneguy]

Check the teeth inside of the clamps to make sure they are not loose. I would bet that your cables are fine and there was just a bad ground connection. Were you connecting the ground to the battery or to frame ground? Don't do the spark trick again bad things happen to computers like that.

Bryan

 

[Boost231]

+1

 

[Turbo6Smackdown]

Check the teeth inside of the clamps to make sure they are not loose. I would bet that your cables are fine and there was just a bad ground connection. Were you connecting the ground to the battery or to frame ground? Don't do the spark trick again bad things happen to computers like that.

Bryan

I was grounding to the battery. My cables are pretty much new. Nothing's wrong with them.

 

[Blown&Injected]

You just did not get a connection the first time. Just a slight arc can break the connection.

 

[83ttypecooled]

Hi,
I think you were dealing with a bad battery on your friend's car. The extra resistance of your longer cables meant your charging system wasn't enough to start the buddy's car.Your other friend's cables, being shorter, managed the task, but who knows what his charging system is like.Batteries, when they develop an open circuit between cells, become unchargeable.Today's batteries pack a huge amount of power, in a small case. Engineers have compromised with more plates, but less lead.Less lead means less times the battery can be cycled.You run one dead, you lose 20% efficiency.And so it goes, every time it runs flat. Also, heat is the biggest enemy of all,and will wipe out even a constantly recharged battery in a couple of years.Location of batteries is critical. I know, you don't have much choice in the matter when you buy a car.However,as an example,my Buick Riviera,vintage '96, has the battery stowed underneath the rear seat, like a lot of German cars. The stock battery lasted 8 years, with only occasional driving. That is remarkable.It suffered two total discharges that I know of, and came back to life twice.That's a damn good battery, engineered to be in the right place.
I digress when concerning this topic, since,as a professional auto mechanic, I see these problems daily.Don't condemn your cables;they were doing their job, but your system did not have the oomph to do the job. Good luck with your issues.

 

[GSTOY]

You mention that you have thick jumper cables, what guage are they? The higher the number guage, the less amperage will be available to the other vehicle. The lower the number, the better. Think of it this way, small wires can only carry small loads, bigger wires, larger loads. As the wire gets longer, you now introduce resistance. In order to combat resistance, you need a larger wire.

Are the cables on your jumpers crimped to the connector or soldered?

Crimped connectors add additional resistance, plus the length of your cable, and the guage of the cable, reduces the total amount of available amperage to jump start another vehicle. It could also have been something as simple that you didn't get a good bite on the battery terminals, and your friend did...too many variables..

Steve

72 GS Vert undergoing frame off restro
87 GN

 

[Turbo6Smackdown]

VERY good information guys, thanks. Here's the total rundown, to give you guys a better picture.

A dead battery on the friends car? Yep. It always was dead. It's a spare vehicle that sits outside. Here's the deal. I pulled my bmw (battery in trunk) to the dead truck, and tried to jump it. I don't know the guage of my cables, but they're some of the thicker ones you find at the typical auto stores. They're not the cheap ones by any stretch. My clips at the end are of the crimped variety, not soldered. About heat? No worries there. My batteries in the trunk, and theirs? Well, lets just say theres not a lot of heat in michigan right now.
I got a SOLID connection to their battery. No go. 40 minutes later, no go. Yanked my cables off, threw theirs on, which were 4' shorter, and hooked them up to their older car. (a mid 90's toyota suv of some sort. not that good condition) In 5 minutes the dead car started right up.

So I addressed the dead battery question, my jumper cable clamp connection, the good contact on the battery connection, and the heat issue.
Basically, I didn't do it the scientific way like I always do, as they were in a rush. I should have used their cables on my car, that would have told me about my cables. Next, I should have tried my cables on their jumper car. That would have told me about my alternator. I will replicate this very scenario again for my own peace of mind, later this week. I'm just pissed that I found out that my own car and cables arent enough to jump someone. I gotta determine which is at fault. I can't be carrying around crap jumper cables in the middle of winter. They're brand new too!