Difference between revisions of "Rechargeable"

Rechargeable (view source)

Revision as of 18:15, 10 December 2010

127 bytes added , 18:15, 10 December 2010

→‎Lithium Ion (Li-ion) - 3.7V/cell

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 Because of the higher voltage, Li-ion cells can only be swapped for NiMH or alkalines if the device manufacturer recommends it (Be careful! A fully charged li-ion battery has 3 times the voltage of a NiMH cell). Some flashlights that use two CR123A batteries can take a single 18650 battery (though this battery is wider than CR123A cells) which offers substantially more capacity than the two smaller cells together.
-Li-ion cells must be monitored more closely than other chemistries. If they are charged too high (above 4.2 volts) or discharged too low, they can overheat or cause a fire. Some good advice is that if you don't have a volt meter and aren't willing to monitor the cells during use and won't be able to watch the cells the entire time they are in a charger, then you shouldn't be using them. See [http://www.candlepowerforums.com/vb/showthread.php?t=235164 this thread] for safe use of li-ion batteries. Cells are categorized as being "unprotected" or "protected." Protected cells include circuitry that will essentially turn the battery off if the voltage goes too high, too low, the drain is too high (the current drawn from a li-ion cell should not exceed 2C), or the polarity is reversed (not all protected cells protect for every one of those cases, and the voltage cutoffs vary as well). For this reason many people recommend protected cells. However, the low-voltage protection often kicks in only when the battery voltage goes below 3 volts, but 3.6 volts seems to be the point where most people recommend recharging the battery. The protection is there to prevent a fire, not to tell you when your battery should be recharged. See [http://www.candlepowerforums.com/vb/showthread.php?t=106242 this CPF Thread] for info about protection circuits. In the past, 10440 cells did not come with protection circuits because they were too small. However, some have recently (late 2009) come on the market (they may be too long to use in most AAA lights).
+Li-ion cells must be monitored more closely than other chemistries. If they are charged too high (above 4.2 volts) or discharged too low, they can overheat or cause a fire. Some good advice is that if you don't have a volt meter and aren't willing to monitor the cells during use and won't be able to watch the cells the entire time they are in a charger, then you shouldn't be using them. See [http://www.candlepowerforums.com/vb/showthread.php?t=235164 this thread] for safe use of li-ion batteries. Cells are categorized as being "unprotected" or "protected." Protected cells include circuitry that will essentially turn the battery off if the voltage goes too high, too low, the drain is too high (the current drawn from a li-ion cell should not exceed twice the nominal milliam hour capacity in milliamps - so a 2000mAh cell should not be asked to produce more than 4000mA (4 amps)), or the polarity is reversed (not all protected cells protect for every one of those cases, and the voltage cutoffs vary as well). For this reason many people recommend protected cells. However, the low-voltage protection often kicks in only when the battery voltage goes below 3 volts, but 3.6 volts seems to be the point where most people recommend recharging the battery. The protection is there to prevent a fire, not to tell you when your battery should be recharged. See [http://www.candlepowerforums.com/vb/showthread.php?t=106242 this CPF Thread] for info about protection circuits. In the past, 10440 cells did not come with protection circuits because they were too small. However, some have recently (late 2009) come on the market (they may be too long to use in most AAA lights).
 Li-ion cells are available from DealExtreme or KaiDomain under suspiciously similar brandnames like Ultrafire, Trustfire, etc., but most CPF members recommend AW cells (available through some online dealers and directly from AW via [http://www.cpfmarketplace.com/mp/forumdisplay.php?f=13 CPF Marketplace/Dealers] under the latest AW's LiIon Batteries Sales Thread) which are of consistently higher quality and have better protection than the cheaper cells. Some brands of 10440, 14500, and 16340 cells are longer than their AAA, AA, and CR123 counterparts, so make sure you are getting cells that are not too long and that your light can deal with the size variance by reading the forums and reviews of the batteries. Just because a cell is sold as an 18650 does not mean it is exactly 65 mm long: some are 68 mm long.