NiCd / NiMH Batteries:

Questions:
1. What is NiMH and what is a NiCd? What's the major difference between the two types of batteries?
2. What is the voltage of a NiMH / NiCd rechargeable battery?
3. How much better are NiMH rechargeable batteries compared to vs. NiCd rechargeable batteries?
4. What is the Memory Effect of a NiCd battery? How can I avoid it?
5. Do NiMH batteries have Memory Effect?
6. What is the self-discharge rate of NiMH batteries?
7. What is cycle life?
8. How environmentally friendly is NiMH rechargeable batteries?
9. How should we store NiMH batteries?
10. Are alkaline batteries better suited to some uses than NiMH rechargeable batteries?
11. What are the disadvantages of fast charging over slow charging?

1. What is NiMH and what is a NiCd? What's the major difference between the two types of batteries?

Answer:
NiMH refers to Nickel Metal Hydride and NiCd refers to Nickel Cadmium. The major differences between the two types of batteries are is capacity, memory effect and environmental friendliness. NiMH batteries have high capacity, no memory effects and environmentally friendly. If you are under the illusion that rechargeable batteries are not very good then the chances are that you have been using older Alkaline rechargeable batteries (which are rubbish) or NiCd batteries suffering from memory effect and you have not been aware of the effects of Memory Effect. <back>

2. What is the voltage of a NiMH / NiCd rechargeable battery?

Answer:
NiMH & NiCd batteries share the same nominal voltage of 1.2V per cell, whereas batteries using a different type of chemistry system. <back>

3. How much better are NiMH rechargeable batteries compared to vs. NiCd rechargeable batteries?

Answer:
NiMH batteries are the results of recent technology advance. NiMH batteries last much longer than NiCd batteries per charge. NiMH batteries also are environmental friendly because of elimination of cadmium toxicity concerns.  Today, more and more high-drain devices consume battery power quickly. Consumers will greatly benefit from the value proposition delivered by NiMH.  Not only do they deliver more power, lasting longer in high drain devices, but they also can be charged up to 1000 times. NiMH batteries are much better than NiCd batteries. 

4. What is the Memory Effect of a NiCd battery? How can I avoid it?

Answer:
If a NiCd battery has not been entirely emptied before the next charge, the charge will not be complete and will set a new lower energy capacity. Over time it will appear that the battery is no longer holding a charge. This is called the "memory effect". To avoid this, it is best to occasionally discharge NiCd batteries entirely as this will ensure optimum performance and help lengthen the life of the battery. You should discharge NiCd cells before every fifth to tenth process of charging in order to avoid the feared memory effect. The memory effect has the consequence that the not used parts of the cell due to partially discharging are no longer in a position to receive and produce energy. Consequently their operating times become shorter and shorter and the cells have to be recharged more frequently. This often misunderstood feature of NiCd batteries has possibly given some users a bad impression of rechargeable batteries in the past. NiMH batteries don not have memory effect. <back>

5. Do NiMH batteries have Memory Effect?

Answer:
NiMH batteries have no memory effect.  Memory is a type of problem that traditional NiCd batteries usually develop. You probably have heard that in order to maintain the life and performance of rechargeable batteries, you have to fully drain the batteries before recharging them. Thanks to "memory free" technology used for NiMH batteries, you can charge them anytime you wish, regardless if the batteries are fully drained or not. <back>

6. What is the self-discharge rate of NiMH batteries?

Answer:
If a NiMH battery is left idle after being fully charged, it will gradually loses its energy. This is called self-discharge. In general, the rate of self-discharge ranges from 15% to 20% per month at room temperature. <back>

7. What is cycle life?

Answer:
Cycle life is the number of charge and discharge cycles a battery can achieve before the discharged capacity drops to end of life. The cycle life is generally considered to terminate when the capacity is less than 60% - 80% of the nominal capacity, depending on the specific charge / discharge conditions. <back>

8. How environmentally friendly is NiMH rechargeable batteries?

Answer:
Rechargeable batteries have the greenest environmental credentials. Using rechargeable batteries reduces household waste massively. Globally, 15 billion ordinary batteries are thrown away every year, all of which end up in landfill sites. Rechargeable batteries can be reused again and again which significantly reduces the impact disposable batteries have on the environment. <back>

9. How should we store NiMH batteries?

Answer:
In general, the higher the storage temperature, the worse the capacity retention of NiMH batteries. <back>

10. Are alkaline batteries better suited to some uses than NiMH rechargeable batteries?

Answer:
This really depends on what you are using the batteries for.  For most high drain electronic devices, like digital cameras, rechargeable batteries will continue to work much longer than alkaline batteries. In fact in devices like digital cameras, NiMH batteries will run on a single charge for 3-4 times as long as they would on an alkaline battery. Alkaline batteries can be the better choice than NiMH or NiCd for some uses.  Alkaline Batteries are more suitable for use in low-energy consumption appliances like digital clocks or remote controls.  Rechargeable NiMH batteries are the better choice for high drain applications. They lat much longer on a single charge and don’t have to be discarded after a singer use. Alkaline batteries are comparatively very expensive. <back>

11. What are the disadvantages of fast charging over slow charging?

Answer:
Yes there are some factors to take in to consideration when comparing fast charging versus slow charging, but basically as long as you have a good quality charger that does not literally fry your batteries, it all boils down to your needs and preference. Basically to use a simple analogy, fast charging is sort of like when you drive your car at higher speeds, you get to your destination faster but there is a little more wear and tear on your vehicle. However on the other hand when you drive your car slower you will get to your destination a little later with less wear and tear on your vehicle. But in the end the differences won't matter much. NiMH batteries, like your car, will normally have a longer useful life if they are not abused, and are charged using a good quality charger, whether or not it is a fast or slow type charger. <back>