Car not starting. Clicking noise.

[SauRoNZA]

And that spark will do what? If you're scared about the hydrogen, then you should have first noticed the dramatic physical damage to the battery, in which case you shouldn't be attempting a jump anyway.

As for overloading things, coming from someone who has designed and built several prototype trucks, no. Connecting to chassis gives you a near identical potential to any electronics as if you had connected straight to battery. And a proper jump connection gives you a parallel connection, so there is no chance of a double voltage, I don't understand where that comes from? At the end of the day the fact is that battery ground is directly connected to the chassis, so electrically it is the same point.

Like I said I'm no auto electrician I just follow the manual.

Battery to battery has always resulted in very big sparks for me which I take as warning you are doing it wrong.

The hydrogen thing does take it a bit far I agree.

 

[SauRoNZA]

So basically, connect to chassis to avoid less than 10 milli Ohm of resistance.

edit: in reality, you're probably adding more resistance connecting to chassis. Notice how chassis rarely sparks? That's because you're making a bad connection. Lots of resistance = no spark, little resistance from a good connection (eg battery terminals) = spark. When the manufacturer makes a ground connection they screw into the chassis by under sizing the bolt hole to ensure a really good connection, and that is usually before paint as well. You're coming along after paint

Isn't that specifically why the chassis connection areas are paint free and "Raw" maybe?

 

[Colin62]

It depends on your approach to jump starting - are you trying to put sufficient charge into the flat battery (and provide some extra current) or are you trying to turn the starter motor using current through the jumper leads irrespective of the state of charge of the flat battery.

If the latter, then connect the earth as close (electrically) to the starter motor as possible. If you're trying to put some charge into the battery, then it probably doesn't matter as much, but you'll get best results by connecting directly to the battery.

My preference is to let the running car push as much charge into the flat battery as possible, and let that do as much of the work as possible. Mainly because without really good jumper leads, that's the best way to get the car running.

 

[Archer]

Isn't that specifically why the chassis connection areas are paint free and "Raw" maybe?

I don't recall any points like that on my wifes car (not that I've looked very hard), guess it'll depend on whether it is a steel or aluminium chassis (I wouldn't want unpainted steel near the coast ). Definitely nothing on my bike. But ya, if you have a spot like that where you have access to raw metal, go for it. But it is really not much different to connecting to battery negative.

 

[SauRoNZA]

I don't recall any points like that on my wifes car (not that I've looked very hard), guess it'll depend on whether it is a steel or aluminium chassis (I wouldn't want unpainted steel near the coast ). Definitely nothing on my bike. But ya, if you have a spot like that where you have access to raw metal, go for it. But it is really not much different to connecting to battery negative.

Normally on the engine block you have a piece of raw metal specifically for this purpose.

Not so sure with newer cars and all the covers they have (never needed to start new ones) but between my Corsa the odd CitiGolf or Tazz there were always these raw points that I was told was specifically made for this purpose.

Hey I just do what the manuals say and having tried the direct method a few times with shocking results that has never failed me.