Ever stopped to help drivers broken down on road?

[supton]

Originally Posted By: Superflan
I’m no electrical engineer but how grounding distant from battery, given the multiple ground cables thickness, can dump current spike? When I do clamp cables, I’m more worried about voltage spike when it does sparks and crackles. And this happens even when I use available clamping points that are designed to on some vehicles.

So, the thing is I understand your concern, that YOU came to help, but maybe it’s just rockstar symptom. I’m with you on it, though nowadays I don’t exhibit it unless life-threatening move.


Even if the resistance is kept good and low, it still adds series inductance. Plus I don't think that series resistance is quite that low. All of which lowers the peak current that can flow initially.

 

[Virtus_Probi]

Originally Posted By: supton
Originally Posted By: Superflan
I’m no electrical engineer but how grounding distant from battery, given the multiple ground cables thickness, can dump current spike? When I do clamp cables, I’m more worried about voltage spike when it does sparks and crackles. And this happens even when I use available clamping points that are designed to on some vehicles.

So, the thing is I understand your concern, that YOU came to help, but maybe it’s just rockstar symptom. I’m with you on it, though nowadays I don’t exhibit it unless life-threatening move.


Even if the resistance is kept good and low, it still adds series inductance. Plus I don't think that series resistance is quite that low. All of which lowers the peak current that can flow initially.


You put two low impedance voltage sources in parallel, any resistance you have in the circuit to help limit current spiking is a good thing. My battery can put out something like 650A for a cold crank...that is to maintain an output of 7.2V, so we're talking about an internal impedance of something like 10mOhms. The cables themselves will add some resistance (IDK how much), the connections themselves obviously aren't perfect, but I'm going for adding even more R by not connecting directly battery to battery for even more margin. The comment about the sparks not being by the battery to prevent gas ignition is also a good one.

Look, I jumped people battery to battery when I was younger and I'm still here to tell the tale, but thing are going to be done my way when my vehicle is doing the jumping. Any little thing to help make an unsafe activity a bit more safe is a good thing in my book.

 

[JLawrence08648]

Yes, many times. At one time you could fix the car on the road. Today with all the electronics, unless it's a flat tire or out of gas, a garage repair.

I've put out 6 car fires throughout the years, always carry a fire extinguisher. I've ashtrays asked for reimbursement of the extinguisher but they all refused. The last before I put out the fire I asked for $10 for some reimbursement. They refused. I left with the car burning and the woman screaming and cursing at me and still refusing to pay me $10. Oh well.

Am I a mean sob?

 

[oil_film_movies]

Originally Posted By: supton
Even if the resistance is kept good and low, it still adds series inductance. Plus I don't think that series resistance is quite that low. All of which lowers the peak current that can flow initially.

Back in the old days, when cars had chrome bumpers, the procedure was to connect the bumpers of the two cars.
Now, we usually expect to see some negative and positive posts, one black and one red, away from the battery. Or at least one red positive one and a bare metal bracket attached to the block somehow for negative ground.

Funny, I needed a jump at a rest stop in Kansas 7 years ago, and the jumper's owner and I could not find a positive post or terminal on the jumper's car!!! Embarassing for both of us really. Chevy Equinox, early 2000's model. Buried the posts/terminals real good.