Thanks everyone for getting this rolling. Please, more comments.
So far, I get this much. Please correct all of this as you see necessary.
Make sure the dead car is in neutral, with the parking brake set and wheels chocked.
The good car should be turned off, and have itself secured (probably in Park) with the parking brakes set. You should never have to start the good car, it should have plenty of cranking power. Besides if you do start it, that seems to increase the chance of blowing ITS computer, turning the helper's good deed into their nightmare and your ulcer. I guess if you want to be ultra-safe you could disconnect the good car's negative battery terminal (requiring a tool), but be aware this will likely upset the car's computer/radio/alarm/seats/backup-camera/auto-parking system/transwarp-drive/etc.
Dead car: Turn everything off. All lights, blowers/motors, radios, even shut the door if you have a dome light. Don't turn anything on until the cars are disconnected. Unplug all accessory adapters and aftermarket stuff. (Editor: If you have a battery cut-out, and haven't turned it on yet, then go directly to Jail. Do not collect $200.)
Good car: Red onto positive battery terminal.
Dead Car: Red onto ground (chassis, block, starter case/bolt? Advice please.) Both red hook-ups are done, to be removed after start-up, remove it from the dead car first when the time comes.
At dead car black onto starter post/battery negative. (Note: One connection is not hooked-up, black to the good car's negative battery post. Controlling this cable from the good car end of things is safer than trying to make this momentary connection while starting the car in the engine compartment of the dead car.) Some seem to indicate it's okay to go the battery ground terminal vs. the starter post, yes/no? Connecting to the battery seems to expose more of the bits to being blowed-up, but the battery disconnection will be easier to do than from the starter post (of a running engine
, even though it's away from the spinny pieces). A thought: Can you get to the starter post from under your car? Maybe you feel this is a safer place to reach under and disconnect after the car is running. (Remember chocks/brakes please.)
Dead car: Switch on
Dead car: Starter on
Cable-person/Helper will momentarily touch black coming from the dead car starter/battery to the good car's battery negative terminal. (Starter should spin rather well?) Cars are connected, hopefully for the shortest amount of time possible.
Caution: When lead-acid batteries charge/discharge they off-gas hydrogen and oxygen, a combustible combination. Try not to make too many sparks nearby lead-acid batteries, such as when you touch the cable to this negative post of the good car. Touch the connector with force and confidence. Oh yeah, they're called lead-acid because they have a sulfuric-acid solution in them.
Not something you want to a) wear, b) clean-up.
When it starts: Cable-person/Helper will quickly remove good car black from good car battery negative terminal. Cars are disconnected (but keep track of the end of that cable for a few more moments, don't touch it to any metal surface). Release starter button like you normally instinctively would.
Keep it running.
Remove dead car black cable from starter post/battery. Black cable is now safe.
Remove dead car red cable from previously selected (positive) ground.
Remove good car red cable from battery positive terminal. Both cable ends are now safe.
Cautions: While doing this be aware of fans, belts, pullys, and dangly things even/especially hair/headwear/neckwear/jewelery. If you have gloves and protective eyewear they might be a good things to put on. (Note to self: put these in the back of the car now.) Check one more time to make sure the car is in neutral, with the brakes set.
Is there any way this is not a two-person job, it seems you need a 'starter' and a 'cable-person'? The cable-person job can be made safer depending on where you hook-up (and on who the starter person is... Check the brakes/neutral again. please.).
Any comments on 6v jumper cables vs. 12v cables? [Edit: Sorry, was off writing when Prof. Henry's above post came through.] How about the idea of just carrying a motorcycle battery in place of a hot-shot would they have enough amps to get a satisfying crank?
-VeryTangled/Jeff