Charging a car battery question.

[perplexabot]

Hey. Was jump starting and charging a car battery a couple of days ago for the first time. I connected the positive of the bad battery to the positive of the good battery, then connected the negative of the good battery to a solid metallic, non-painted part of the engine on the bad car, or the body frame.

My question is: How is this a closed circuit? Is the negative terminal of the bad car's battery connected to its "solid metallic parts/body frame?"

 

[marcusl]

Yes, the negative is grounded just as you said.

 

[perplexabot]

Yes, the negative is grounded just as you said.

Thank you for the quick reply. My mind is now at ease.

 

[perplexabot]

Ok now a follow up question if you don't mind. Why then not connect the good battery's negative directly to the bad battery's negative?

 

[marcusl]

Batteries produce hydrogen gas bubbles as they charge, and this can be vigorous for a fully discharged battery. Connecting to chassis ground keeps any sparks away from the battery and flammable gas.

 

[perplexabot]

Thank you.

 

[jim hardy]

Follow your battery wires.
Most GM cars have a positive post near the battery for jump-starting. It'll be underneath a red plastic pop-up cover.
Sure easier than trying to grab that battery side-post terminal, and safer too as marcusi pointed out.

I like to connect negative to a substabntial piece of metal on the engine. I figure starter is bolted to engine block, so starter's heavy current doesn't have to flow through a potentially weak frame wire on its way back to my jumping battery's negative..