Simple Li-Ion Charger.
the actual capacity of the cells I have is unknown, I'm playing it
careful and charging them at about half the recommended current.
Because the cells are wired in parallel, the charging current for
each one is 0.25 Amps.
In the circuit, I use a 126 Volt AC
output wall wart that plugs into the charger box that is taped to the
batteries. When first plugged-in, nothing happens until the
"Charge Start" normally closed button is pushed momentarily. This
causes the Schmitt-Trigger circuit to pull-in the relay and start
charging the battery pack. The light bulb, out of my box of
assorted light bulbs is most likely a 6-Volt. I chose it because
it limits the charging current to about 0.5 Amp. total. In
addition to serving as a ballast resistor, the light bulb gives a
visual indication when the battery pack is being charged.
capacity of AA Lithium-Ion cells varies but can be as high as 4
Amp/Hrs. Impressive! The articles say that this type of
battery shouldn't be completely discharged. The minimum
recommended "stop use" Voltage is 3 Volts per cell. They
say the life of the batteries will be adversely affected if they are
discharged below this point.
They also say that the batteries
are happy to be stored at less than full charge, a nice change from
NiCad and Gel Cell batteries. I plan to cycle the charger
after use then just let the pack sit on the shelf until I'm ready to
use it again. Then, I'll give it another charge cycle.
Since I'm not charging them to their maximum Voltage (4.2
Volts/cell), I think I'm safe with a charge cycle before storage.
far, the pack will power my McVickerish engine for over 12 hours and
the batteries are still making 11.6 Volts! I may haul out the
Jack of All Trades ignitor engine sometime and see how the battery pack
does with that kind of load. The instantaneous current is around
2 Amps. I've got high expectations and will add the test results
here when I have them.
If you are looking for a new Lithium-Ion
battery pack, I'd suggest that you get one of the imported ones.
Some of the packs come with the charger and the price is around
$20. Look on Amazon or Ebay.