On Thu, 11 Apr 2019 04:32:29 -0700 (PDT), "
wrote:

On Thursday, April 11, 2019 at 6:40:23 AM UTC-4, Stephen Wolstenholme wrote:


That depends on the size of the "set"

Let's look at that. A typical alkaline battery runs about 2.5 AH at 1.6 VDC or so. Meaning it will make about 4 watts for about an hour - a measure of the actual current it can produce.

The typical starter on a 2.0 liter gasoline automotive engine draws about 200 A at start. More if the engine is cold, more if a diesel, more if worn and so forth, but for the purposes of this discussion, figure 200 A at 13.6 VDC. That comes to 2,720 watts for about three seconds - average crank time for a well-tuned, cold engine. Now, work the math and figure the number of AA batteries required to put that much charge into a battery for the requisite period.

Now, figure that the battery failed for a reason. What does a sulphated cell look like? It can be done. But the cost, trouble and time require, as well as the likelihood of the source materials should be lying around....

Keep that solar panel trickle charger. It will be a much better bet.

Peter Wieck
Melrose Park, PA
Speaking of solar chargers, I have one charging the 6 volt battery in
my Ford 9N tractor. The panel is rated at 7 watts max. Here in the
great Pacific Northwest, with the cloudy days and all, The thing is
charging at about 17 milliamps. Open circuit voltage is 18 volts. But
when the thing is connected the battery voltage measures at 6.5 volts.
So I don't think there is any danger of overcharging unless the sun
goes nova and really lights the panel up. But I was wondering how to
calculate the wattage. is at 18 volts times 17 mA or 6.5 volts at 17
mA? I think I should use the open circuit voltage but I don't know.
Eric