| Den in USA |
2011-05-13 13:00 |
Re: charging from USB for 4 hours and still going...
Quote:
Originally Posted by AgogData
(Post 1005481)
USB chargers take longer than the wall charger, wall charger takes about 1.30 hour while the USB charger takes about 3-4 hours. I once heared a theory but im not sure weather its right or not saying that the USB charger is more stable than the wall charger and makes the battery last longer.
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You are correct. When a battery has been discharged, it has a low internal resistance when it is connected to a charger. If the charger can provide 900ma current, then the battery will heat up until the internal resistance goes higher. If you use your usb port on a computer to charge your battery, you are limiting the current to about 500ma. This also limits amount of heat being dissipated by the battery during charging. Less heat, longer battery life. In the old days, we used a formula to determine the proper charge current for a battery. If a battery was rated at 1200ma hours we would limit the charge current to 10% of that, or 120ma. Then people insisted on being able to do a "quick charge". Instead of charging at the 120ma, they built chargers that charged at a much higher current. now, instead of replacing batteries every three years, they had to replace every year or even every six months. |
