The discussion centers around the proper method for jump-starting a car, emphasizing the importance of connecting the negative terminal to a grounded metal point away from the battery to prevent ignition of hydrogen gas. Participants highlight that while connecting both negative terminals is common, the safer practice involves grounding to minimize spark risks. Historical context is provided, noting that older vehicles sometimes had positive chassis, influencing jump-starting techniques. The conversation also touches on the hydrogen gas release during battery charging and the necessity of maintaining distilled water levels in lead-acid batteries.
PREREQUISITESAutomotive enthusiasts, mechanics, and anyone involved in vehicle maintenance or repair will benefit from this discussion, particularly those interested in safe jump-starting practices and battery care.
I learned from my grandfather, back in the 60's. He was a heavy-equipment mechanic and he insisted that I learn HIS way of doing things when I was learning to drive and learning how to fix automotive stuff. My father was less anal about the negative-connection, but I respected my grandfather's experience and skill. I don't know if more modern sealed batteries are less dangerous in this regard, but it's an easy rule to remember and follow so I still do it.Integral said:I have always connected the negative terminals, never had any problem. In the days of metal bumpers you could just touch bumpers and run a jumper lead only between the positives , in many cases it is easier to get to frame connections then the battery, in reality it does not make any difference. Just get the best connection you can.
I think you may have tumbled to the problem that made the old-timers come up with the frame-to-frame rule. If the person with the dead car is anxious to get moving and removes the ground clamp from the negative terminal first, there could be a "pop".pallidin said:Also, I thought that lead acid cell batteries emit hydrogen only during charging. So, doesn't a dead/weak battery have nearly zero hydrogen gas discharge above it when connecting jumper cables?
spenson said:Hmm, that's interesting. I always thought it was to add a bit more resistance to the circuit. Never considered the explosion aspect. Looking through a couple of Google searches I actually found an incident of someone blowing the top off their battery because of this.
Sakha said:So eventually if you charge a lot your battery you will end up with no hydrogen and no power right?
You top off the cells with distilled water, not more acid.Sakha said:Distilled water? Dont those batteries have sulfuric acid in the small vents?
turbo-1 said:You want your negative connections (I do both!) to be on grounded metal some distance away from the batteries, so that any sparks creating when disconnecting the jumpers won't ignite hydrogen liberated by the battery.