Generally speaking, if the wall wart charger was the one that came with the radio, and you stick with the voltage battery (RX) that came with the receiver, the wall wart charger won't overcharge. But, normally speaking, you don't normally leave a charger on for multiple days, usually, guys just put the thing on the night before and let it charge overnight. This is fine for a typical 700 mah battery, or the standard TX 9.6 volt battery of about 700 mah or so. They will usually charge in about 14 hours or less, or overnight.

When people increase the capacity of those batteries, say to what I have, 1650 mah, then the wall wart charger will also work ok, but for a fully depleted battery, 1650/50=33 hours. That is ideal time. Add about 10% for overhead and you now have almost 37 hours of charge for a fully depleted battery.

Fast chargers, field chargers if you wish, will charge at much higher rates, the Sirius, for instance has three settings, 250, 500, and 1000 mah. But, as said, the batteries must be able to handle this higher rate of charge or they will be damaged.

If a battery states a 1C charge rate, then the maximum rate of charge is 1650 mah (for my battery). But, most batteries say that .1 C is a good rate or 1/10th C or 165 mah is a good safe charge rate, so charging will take 10 hours at that rate for a fully discharged pack.

Most of us don't deplete these batteries fully, so the charge time will be totally dependent on what is remaining in the battery and what it takes to full charge it. For instance, a 1650 mah battery depleted to 950 mah, has depleted 700 mah and will take about 7 hours at 1/10th C to fully charge, or, depending on the safe charge rate for the battery, will take somewhat less.

Moral to the story? Read your battery specs and see what the capacity is, what the charge rate, and what the discharge rate is (less important for TX/RX operation, but very important for batteries used for propulsion power). Determine what the charge rate and the rate your charger will provide and do the math. You can't go wrong.

If you are uncertain, then get a discharger and run it through the discharger to depletion and recharge to full capacity. Siruis, again, sells a battery discharger with a digital display. You hook it up and discharge the battery through the discharger, and it will show what the total current flow was through the discharger. That will tell you what was left. For instance, a 700 mah battery, discharged through the discharger, the indication shows 300 mah. That means that 300 mah was left and you obviously used 400 mah during your flying time. This can give you some idea, for the future, how much you used and how long your batteries will last under normal conditions.

Hope this helps.

CGr.