I need a 500 mA current to charge my device. The chargers I have say output 5V-1A and 5V-0.85A. Which one is 500 mA? Isn't 1A1000mA? If so, does that mean that the 0.85A is putting out 850 mA? Also, the battery is a 4.2V battery. Will a 5V charger overcharge it? I really cannot afford to overcharge/damage the battery. It goes on an e cig tank and I don't want the battery to blow up in my face. I need the correct charger. Does anyone know for sure what I need? I know I need the current at 500 mA, but what about the voltage?
Both chargers are fine. Your device may require a 500mA charge, and so that's the minimum charger rating you should use. Anything in excess simply won't get drawn from your 850mA and 1A chargers. The device requires a USB charger, and USB voltage is standardised at 5v DC. But charging is a bit like a gradient: you cannot charge a 4.2v battery on a 4.2v DC charger; there has to be a little bit of excess voltage in order to push the charge into the battery.
This is the askerI also had a question about the charging cable and forgot to ask. The device came with a charging cable, but nothing to plug it into. So, will the cable reduce the current to 500mA if the cable has a exact rating resistance in ohms to lower to current to the specified amount? If so, then the charging current would be correct if the cable doesn't overheat and melt. But that still leaves a 5V charge into a 4.2V battery. Is there a built in regulator and overcharge protector in the device I wonder? If it helps, it is a kanger tech top box.
You don't need to exactly match the amps, the rated amps are the maximum the source can provide, not the amount your device draws. All USB's are 5v, and the charger compensates for this, the battery voltage is largely unrelated. If you are just connecting the battery direct to a usb, it won't work.
