Rechargable Battery Technologies

NiCad
NiCad not allowed in EU consumer products.

NiMh
Wikipedia
1.2V/cell
Charge voltage is 1.5
Fast Charge -
Constant Current at 1C
Fast Charge Termination -
Hard to do with delta V because the delta V is very small.
Typical charge control chips use a timer and battery temperature.
Slow Charge (0.1 to 0.25 C)- Not recomended
Because hard to detect the delta V and temperature rise not so predominate.
Trickle Charge -
There seems to be differences in advice between battery manufacturers
Typically C/30
 Panasonic advise a pulse of current when the voltage gets below 1.3V
(i'm not sure how this works given the normal cell voltage is supposidly 1.2 V).
My Thoughts
If the battery is integrated in the product,
Measure current in and out of the battery to know who charged the battery is and then use time and temperature.  I suspect that over time the capacity will reduce and so the maths in the CPU will need to take this into consideration.


Lithium