Elf,
Thanks for a very informative post! I have one question for you. I have a charger that says it is for liFePo4 3v. It fits either CR2's or CR123's. Can this charger be used to charge 3v lithium ion batts?
Without knowing more, I must say do be very careful charging any Li-type
batteries and
only use a charger recommended specifically for the batteries in question. The chargers are built to the specs of the battery type and are not cross-compatible unless the charger distinctly says so. Li-Fe and Li-Ion
batteries are distinctly different in chemistry.
I do have a couple chargers that will charge Li-Ion,Li-Po, and Li-Fe, but they are not your normal kind of chargers. Unless you are into this kind of hobby (and expense), your charger likely does not have this capability.
To give an example of how this is a very precise method for a particular cell -
When my chargers charge LiPo cells with a 1C charge rate, the charger first verifies that the voltage of the cells are okay.. not too low, not too high. Then it starts pushing a little current (mah), and then rapidly increasing the current while watching the voltage carefully (so it NEVER exceeds 4.2v at the battery). For the batteries I typically use, the current (charge rate) gets pushed up to 1C (in the case of 5000mah batteries, that would be a 5000mah charge rate) pretty quick. In about 45 minutes, the cells are getting pretty full, and voltage climbs to 4.2v under charge. At this point the charger starts backing off the current dynamically, still pushing as much into it at a time as it can without exceeding the 4.2v threshold. The charge amps keep backing off, until we are finally down to only 100mah charge without exceeding the 4.2v. The battery is now nearly (99+%) charged. A minute or two later, the charger will decide that it is impossible for it to keep charging even at the low 100mah charge without the cells going over 4.2v, and it shuts off charging altogether. The charge is done in just over an hour.
Your charger, while not this advanced, still needs to be able to appropriately charge the cell in question. For each kind of cell chemistry, there are "magic" voltage numbers never to exceed or go below, and "magic" charge and discharge rates never to exceed. Yes my LiPo batteries can safely charge in just over an hour. They can also perform bursts in excess of 200 amps on discharge. Any current PV batteries will likely go boom if either of these are attempted with them (for sure the discharge part).
Always use Li batteries safely. Li batteries can go boom if overcharged. They can go boom if over-discharged. They can go boom if the discharge rate is too high (think of a stuck button, or a short circuit, etc). They can go boom if you attempt to charge one that has been over discharged.
I'm not trying to spook you here - Li batteries are amazing - they just need a whole world of care that normal rechargables(NiCd,NiMh) do not. Be careful, and all will be fine
