RC Battery Basics
I've learned through experience that knowledge of proper care for rc batteries (specifically the battery that powers the vehicle) is crucial to performance as well as much kinder to the pocket book. I have a box full of dead and partially ruined batteries that got that way through simple ignorance. One hobby shop clerk I know claims to still have and maintain a NiCad battery pack that is 10+ years old and as good as when he first purchased it. Goes to show that a little care goes a long, long way. It's extremely important when you figure that batteries typically cost $10 and up.
Choosing an RC Battery
RC batteries are re-chargeable and come in 3 types:NiCad (Nickel Cadmium), NiMH (Nickel Metal Hydride),Li-Po (Lithium Polymer). Your choice depends on budget and performance requirements. NiCad is the cheapest but lowest in terms of capacity, has memory problems and is heavier. NiMH has greater capacity and no memory problem, but is also heavy. Li-Po has the greatest advantage being light weight and having the greatest capacity of the 3. Li-Po batteries are more expensive, require special chargers and for optimum performance, some require a balancing charger (only for the newer Li-Po batteries with a special balance charger lead).
RC Battery Care
When you first purchase the battery, follow charging instructions. You may need to charge it for 16-24 hours for the first charge. For OPTIMUM PERFORMANCE, follow manufacturers' instructions VERY CAREFULLY! NiCad batteries should be partially drained after each use to prevent the memory problem. NiMH's don't have this problem. In the case of Li-Po batteries, it's crucial you DO NOT drain the battery completly or you'll likely ruin it (That's my experience!). In fact, when your rc car, plane or helicopter using Li-Po's starts to lose power, it's time to stop and re-charge. With the newer Li-Po's it's best to use a balancing charger which charges each battery cell indepently and therefore produces optimum output. With all 3 types, you should always use a peak detection charger to avoid over charging. This is especially important with the Li-Po batteries which can explode if overcharged! Also, when using a 12 volt charger that plugs into the cigarette lighter, DO NOT charge while the car is running. Your automobile typically puts out 14+ volts when running and overcharging of your rc battery will result (more experience here).
RC Battery Voltages
Rc batteries usually come in packs containing 2 or more "cells" (the tiny micro rc's are the exception). The voltage is determined by the number of "cells" multiplied by the the amount of voltage per cell. So, in cases of an rc battery with a worn label, you can still determine the total voltage. Start with the type of battery you have. The heavier NiCad and NiMH batteries are both 1.2 volts per cell (the cells are usually round in shape), while the Li-Po's are 3.7 volts per cell and square in shape. Using this information, you can readily determine that a NiCad battery with 7 cells puts out 8.4 volts while a Li-Po battery with 2 cells puts out 7.4 volts. This is important to know because your electric rc car motor runs faster at higher voltages and longer on higher capacity plus the weight factor makes a huge difference as well.
RC Battery Types: Pros and Cons
Again, here's the battery types and their characteristics at a glance:
NiCad (Nickel Cadmium) Cheap, heavy, not too sensitive to overcharging, best for fast charging, low capacity, memory problems and 1.2 volts per cell.
NiMH (Nickel Metal Hydride) Mid priced, higher capacity, no memory problems, heavy, sensitive to overcharging, uses standard charger and 1.2 volts per cell.
Li-Po (Lithium Polymer)
Highest priced, highest capacity, light weight, special care to avoid flat performance, special charger needed, does best with a balancing charger, must NOT be overcharged, and is 3.7 volts per cell.