Hannan.khan
Newbie level 3
so i am using MAX1555 to make a usb charger for a single cell li-ion battery...any 1 knows how to convert it into somthing that could accommodate 2 cell (li-ion) charging
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so i am using MAX1555 to make a usb charger for a single cell li-ion battery...any 1 knows how to convert it into somthing that could accommodate 2 cell (li-ion) charging
Even in the case of smart battery with charge balance, if them are in series, the terminated voltage of each will be 4.2/2=2.1V, often the total capacity is very less than one normal Li-ion cell, unless maybe they are of another chemistry or with some additives. If they are in parallel, yeah the capacity will be doubled, while the charging operation time need also be doubled with that 500mA USB. right ? Normal USB is with 500mA, while some special USB in car or some handcrafted ones, more current maybe be available.Depends on the battery. If it's a smart battery containing charge balancing circuitry, then you can likely treat it as a single cell with double the voltage. If you just have two "naked" cells in series then you will need a more sophisticated controller (or a separate IC) to handle charge balancing as well.
Obviously you won't set the controller to charge the battery to 4.2V, but twice that. Many controllers will allow for this (though you will need a charger that can step up voltage).Even in the case of smart battery with charge balance, if them are in series, the terminated voltage of each will be 4.2/2=2.1V
max1737 isn't suitable because it can only step down voltage. USB is 5V, which means you need to step up to ~8.4V.so the real problem here is balancing the charge so that drain is equal....so one last question guys will MAX1737 work in this situation i.e. charge via usb....time to charge is not the issue as long as the drainage<charging (which would depend on the number of cells i use)
thanks guys
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