Actually there is no big difference. Handled "properly" both of them might be converted to bombs. Alkaline batteries cannot be charged whereas Ni-Cd batteries can be charged.
Charging an alkaline battery you'll have in instant bomb, overcharging a Ni-Cd battery you'll have a delayed bomb.
Concering cost for power a carefully handled Ni-Cd battery survives up to 1,000 charging cycles. Comparing the prices a Ni-Cd is cheaper (by time) than an alkaline battery because of multiple charging capability.
Ni-Cad batteries are obsolete. They have been replaced by Ni-MH batteries that have 4 times the capacity.
My RC helicopter came with alkaline batteries which did not last long. I now use Ni-MH batteries that I recharge over and over.
An alkaline battery starts with a higher voltage when it is new. But when it is loaded its voltage quickly drops to a lower voltage than a Ni-MH battery.
In addition to the comments above. NiCads and NiMH batteries will self-discharge when not in use 100-10000 times faster than alkaline batteries. Alkalines are great for things like clocks which are low drain devices. They suck in digital cameras and other high drain devices.
That is true with Sanyo Ni-Cad cells used in RC models.
It is not true with Energizer cells. The Ni-MH cell has a lower internal impedance so it provides a higher current and for much longer time.
That's true for standard NiMH batteries but several companies are now selling low self-discharge NiMH batteries that retain most of their charge for a year or more. The come precharged and can be used without first having to charge them.
Yes, I've heard of those. They have a lower capacity than regular NiMH but hopefully that will improve also. They can't beat the 6-8 year shelf life of an alkaline though. So I'll modify my statement to say, "NiCads and NiMH batteries will self-discharge when not in use 8-100 times faster than alkaline batteries."
Yes, I've heard of those. They have a lower capacity than regular NiMH but hopefully that will improve also. They can't beat the 6-8 year shelf life of an alkaline though.
I have some RayOVac "Hybrid" long shelf life "AA" batteries with a 2100mAH capacity which isn't bad, although I guess it's less than the best NiMH.
Of course if you want several years of shelf life than an alkaline certainly makes more sense, since you wouldn't be using the recharge ability of a NiMH much anyway