This video shows how to test and find out the voltage level and polarity of your RC battery using a multimeter. A multimeter is a very simple and low cost device with two wire leads. All you need is to connect the leads to the battery power source.
Assuming your battery is charged and is normal, the voltage reading should be slightly higher than the stated voltage of the battery. If the reading is low, either the battery is not fully charged or that it has become very weak.
One thing very useful about testing voltage this way is finding out if reversed polarity is taking place. If the battery connector is reversely configured by mistake it will damage your speed controller instantly. With reversed polarity the reading will show a minus sign so you know something is wrong here.
