RE: Radio Check
It is not uncommon to see the voltage jump up after only a short time on the charger. That does not mean the battery is charged. If you check the voltage of the battery, under load, you will see the voltage drop sharply after only a minute or two. The load you put on the battery when checking the voltage is supposed to be consistent with the load put on by your Rx or Tx. A typical Tx load would be 200ma. If you just use a Multimeter and do not put the battery under load, you will get inaccurately high readings. Most Expanded Scale Voltmeters (ESV) have a dial that let's you set a load (.5a, 1a, 1.5a). 1a and above is used for LiPos and LithIons.
Depending upon the type of batteries you are charging, a safe charge rate is 1/10 of it's rated capacity. For example, a 1 amp hour battery (1000mah), would be charged at 100mah. Most Wall Chargers that come with your RC Radios charge at 60-150mah for 16 hours. Wall Chargers are good for NiCads and NiMh batteries. Wall Chargers charge at a constant Current rate and do not detect the voltage of the battery so you can overcharge the battery if you are not careful.
If you purchase one of the many Cycling Chargers, you will get more life out of your batteries and better performance. They charge in pulses, rather than constant charging and they anticipate when the battery will reach peak voltage so they do not overcharge. They have many settings to help you set the right charge for your batteries. You can Fast Charge or Slow Charge and you can Cycle the batteries. Cycling allows you to set up the Charge so that once the battery is fully charged, it will discharge the battery at the appropriate rate, recording the capacity of the battery or the time it takes to discharge, then it will charge the battery again. You do not do Cycling often, because it will eventually reduce the life of the battery, but whenever the battery does not seem to be giving you it's rated capacity, a Cycle is in order. It is also good to Cycle the batteries once in the winter time when they are setting on the shelf and not being used.