Well i was always taught to connect the donor battery first, and disconnect it last so the spark theory don't hold water there.

Besides, what about the battery being jumped ? Something is going to spark...

 

Hook up + to + first, then hook up grounds. first ground to be hooked up can be at battery, last one away from battery. Disconnect in reverse order. Spark will not be at battery.

 

Yep, there will always be a spark when the last connection is made, you want that spark to occur somewhere other than at the battery of either car.

Personally, I work around a lot of big batteries dealing with RVs and I just blow at them really hard to try and blow away the gasses.

Good point about the jumping with 14 volts instead of a normal -at rest- 12.8 volts. I suppose if the bike circuits are that sensitive then it could matter. Usually, higher voltage means less current passing through the windings to spin the starter and it should run cooler. I will still always jump vehicles with a running engine, I do not want a two dead engines. Maybe on the dirt bike I'll try the dead engine jump. Willing to risk it because I have a kicker.

 

Wait, do our bikes even make 14 volts at idle?

 

When you jump from a resting battery ALL (or almost all depending on the dead battery's condition) of the current to start has to come over the cables and quite often the voltage drop over the connection points will be enough for it to not work. Anyone who has tried a jumpstart with cheap cables knows this, that first attempt to start barely gets you a click of the solenoid. With the voltage boost from a battery that is being charged, give it a couple minutes and you will be able to get some charge into the dead battery even over a weak connection to help turn it over. Same deal with jump cables like Deej's, that little thing won't supply enough current to power the start but it will get some charge into the dead battery and boost the voltage to make it possible.

Basically, a 12v battery will not charge from 12v, you have to push the electrons around with a higher voltage. Hence the 14.4v typical of 12v automotive electrical systems. The higher the difference, the faster the charge potential up to the point that you start to boil off the electrolyte.

 

Warning!!! Warning!!! Warning!!! NERD ALERT!!!!

 

Deej - are you digging up an old one again just to hassle the nice forum members on here?

 

Hehehehehe well after all he is my Nemesis and we work together. LOL

 

Besides I found that in a search while looking for another post, and didn't realize how old it was....stupid forum is still broke. I'm welcoming members that signed up 5 years ago hahahaha

 

We don't work "together"... you're all the way over there across the water and behind some hills.

And it's geek to you good sir.