Some very rough guesses:

200A cranking current for 2 seconds = 10A charging current for 40 seconds.
Closer to 1 minute than 5, certainly.

About 5.2kJ of energy, and assuming the gasoline engine is about 25% fuel
efficient, that is approximately 1/50 of an ounce of gasoline[1].  That's
not including the amount of extra fuel used during starting vs. running,
which probably puts that 1/50 of an ounce down into the noise.

[1] http://hypertextbook.com/facts/2003/ArthurGolnik.shtml

Dilemma on my hands is along the same lines

I just got finished importing a 1971 Citroen 2CV from France, to my home in the desert of California.  I drove the car 300 miles in France before leaving her in the hands of the freight forwarder.  She ran great, no issues at all.  The boat trip and wait time on both shores inclusive was 4 weeks. When I picked the car up in Baltimore, however, she wouldn't start at all. No click, no sound, nothing

I got a jump start and she started right up, sounding great.  Until we disconnected the jumper cables, when she would almost immediately sputter and die. She's stay on a few moments longer if we let her run for a few minutes before disconnecting the cables, but then would die again, and wouldn't start on its own again at all

Thinking "charging system problem", I ran off to replace the battery -- kicking myself in hindsight for not getting the old one tested before I handed it off to the recylclers -- dumb dumb dumb of me!! At least with a new battery I should be able to start the car and drive it back to the parts store to hopefully get the charging system diagnosed.  Did all that, and the parts store (incorrectly) reported no charging system trouble at all. Their meter showed the alternator to be charging at 13.57, healthy enought to be charging the battery on the brand new battery for this 12V system, very simple two-cylinder vehicle

So, I stupidly left Baltimore on that rainy evening to begin driving as far West as I could get.  Fifty miles outside of Baltimore, as the rain got more intense in the darkness of night, I noticed the dash lights were certainly VERY dim, if not completely gone. And then people behind me were flashing their brights -- how rude of them, I thought, since I was going as fast as I could up these winding steep mountain curves. Well, these people were trying to signal me that I was driving with no lights on at all!!  In the driving rain!!  On mountain curves no less.  That would explain why my wipers kept going off and on and why playing with the light switch (off-on-off-on) seemed to make my engine either gain or lose power, accordingly

To make an incredibly long story shorter, I got her to Palm Springs, not running, and had an alternator guy bench test the alternator. He found it to not be working at all, took the cover off, and found a lead completely missing. Soldering on a new lead, the bench test passed this time. Reinstalled the alternator, I got the car back home (still in tow, though ).  He recommended I charge the battery by connecting it to the battery of my car which did run -- with both vehicles off -- for an hour.  Then disconnect the cables and start the car

Did that, but the Citroen did not start up at all.  So reattached cables, started the car with the good battery (which is a 1972 Totota Land Cruiser FJ40, btw), and started the Citroen right up.  Perfect, great.  But then after disconnecdting the cables, the Citroen died again.  (which is what it had done in Baltimore, too, before I replaced the battery... which I now realize was most likely unnecessary.  Crap!!

So at this point... I have had somewhat better luck by leaving the Toyota off, starting the Citroen, letting her run for a good 5 minutes while connected. Then disconnecting the cables.  Last time I did that she ran for a full 5 minutes before sputtering and dying. And then trying to start the car on its own showed the battery had no charge at all. No power for wipers, lights, nothing.

So do I need a new voltage regulator, too, or maybe instead of the new battery?  And why would this all happen suddenly, after just travelling by ship?

I think tomorrow I can get her to the parts store by asking a friend to follow me and we'll bring the jumper cables along.  I haven't tried charging while driving, but am hoping more power going through the system will be enough to charge the battery.  As you can tell, I'm no expert in these matters, so any suggestions/alternatives, ideas, kind words for a frustrated dude will all be welcome and appreciated

Thanks

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cyclometric

This morning I'm going to remove the battery from the Citroen and drive it to the parts store for testing -- but they'll have to charge it first, before it can be tested, right?  Or, I suppose that if it doesn't take a charge at all, that's enough to prove that it's a defective battery, huh

Thanks

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cyclometric

OK, AutoZone charged the battery -- which had not been done since I bought it in Baltimore -- and now the car starts and runs fine. I drove it to AutoZone and they tried to test the charging system, but their testing equipment kept saying I wasn't running at 2000 rpm, even when I had the choke completely open and the throttle completely open via the gas pedal.  So I think I'll have to test the battery's charge now by hooking it up to a manual battery charger I bought -- I guess I can tell if the system is working by noticing whether the charge is deteriorating after running the car medium distances, eh

Thanks

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cyclometric