Difference between Ni-Cad & Lead acid Battery

         Difference between Ni-Cad Battery & Lead Acid Battery

Advantages of Ni-Cad over lead acid.

1.Greater power to weight Ratio then compared to lead acid

2.CCV of a Ni-Cad battery remains nearly constant during the entire discharge cycle.

3.Ni-Cad battery electrolyte freezes at approximately -60 degree F & is therefore less susceptible to freezing compared to lead acid battery electrolyte.

4.Unlike Lead Acid Batteries Ni-Cad batteries can be stored for long periods of time in a charged or discharged state without damage.

5.Internal resistance of most vented Ni-Cad is very low(less than 1 mili ohm),which allows these cells to maintain a high discharge current & still maintain acceptable voltage levels. The low internal resistance of Ni-Cad battery allows it to recharge very rapidly.

6.Advantage of Ni-Cad is that the active material of the cell plates change in oxidation state only, not in physical state. As a result the cells are very stable even under a heavy load.

Disadvantage of Ni-Cad over Lead Acid:

1 .More Expensive then lead acid.

2. Lower output/cell then compared to lead acid & hence their physical volume is larger then a lead acid battery.

3. In lead acid, High current is available for engine start & relatively low manufacturing cost.

4. The only accurate & practical way to determine the condition of Ni-cad battery is with a measured discharge in the workshop. Whereas in Lead Acid we can determine by three way.

a) By measuring specific gravity

b) By measuring voltage

c) By free gassing while on final charging.

Ni-cad is normally used in Heavy aircraft while Lead acid battery used in General aviation aircraft due to low cost.