How Do I Know Which Battery to Use?
What Type of Battery?
There are various types of batteries on the market today. Different sizes, different technology, different voltages, rechargeable and single use disposable. So how do you know which to use? This hub gives some basic facts about the different types of batteries available.
Rechargeable or Non-Rechargeable?
Batteries can be rechargeable or non-rechargeable. Non rechargeable batteries can only be used once and then need to be replaced. Rechargeable batteries can be recharged up to 500 times.
- Can be charged several hundred times before they become unable to hold a charge.
- They are able to provide a high current output because of their low internal resistance. This means that they can power devices with a high current demand.
- More expensive to buy than non-rechargeables but not hugely more expensive.
- Loose there charge over time through self discharge even when not in a device. This can be up to 30% per month. So a battery is never fully charged when you go to use it , unless you keep it on constant trickle charge. Newer type Nimh batteries hold charge for longer.
- Capacity of rechargeable cells is less than that of alkaline or lithium cells.
Non re-chargeable or primary cells are available in all the standard sizes and voltages; AA, AAA, C, D and PP3(MN1604). The nominal cell voltage is 1.5 volts and 9 volts for the small square PP3 type.
There are several widely available technologies:
Zinc Carbon - These were the first non - rechargeable cells. They have a capacity between one quarter and one fifth that of alkaline cells. They have a relatively high internal resistance and this makes them more suitable for low current drain devices such as radios, toys and low power torches. They don't perform well at low temperatures and high temperatures can dry out the electrolyte.
Zinc Chloride - These are an improvement on zinc carbon having a 50% greater capacity, higher current output capacity and improved leak resistance. They also have better low temperature performance and longer shelf life.
Alkaline - These have several advantages over zinc type batteries. They are able to provide a high current output, they have good high and low temperature performance and have a long shelf life losing about 5% of capacity per year. Alkaline batteries are the most expensive however compared to zinc cells but the difference in price has reduced in the last 20 years as production has increased.
Lithium - Lithium battery voltages range from 1.5 to 3.7 volt. The batteries are expensive compared to alkalines but have have a higher energy storage density. They are suitable for high current demand applications and the output voltage is constant during discharge unlike the sloping voltage characteristic of other primary cells. Lithiums have a very long shelf life and loss of capacity is only about 0.5% per year. Single 3 volt lithiums cells are often built in the CRV3 format which is like two AA cells side by side. This allows them to be used as drop in replacements in devices which take two or four AA cells side by side. 3v lithium coin cells are commonly used to power watches.
When buying batteries, sometimes they are marketed as "high power", "high drain" "long life" etc. It's important to realize that these are marketing terms and the batteries may be zinc carbon or zinc chloride types. If you are buying batteries in bargain basement stores, make sure to check that alkaline is actually written on the packaging to get the best performance battery.
Known as secondary cells, these are available in all the common sizes. The nominal cell voltage is 1.2 volts and 8.4 volts for the small square PP3(MN1604) cell.
NiCd - Nickel cadmium batteries were the first commonly available rechargeable cells. NiCads suffer from a memory effect phenomenon which means that if you just keep topping up the battery rather than fully discharging it, the battery "remembers" the point from which it was topped up and will tend to lose capacity and discharge to this point. Loss of charge during storage is about 20% per month. The batteries have a low internal resistance and can source a high current on demand when used in moderate power devices. The voltage stays relatively constant during discharge.
NiMh - Nickel metal hydride batteries are an improvement on NiCd. They have a higher capacity for a given size of battery but without exhibiting a memory effect phenomenon. They can also provide higher output for devices with a high current demand. Voltage is relatively steady during discharge. The disadvantage of NiMh batteries is that they lose charge relatively quickly, about 30% per month. LSD or low self discharge NiMh cells are available however.
Rechargeable Lithium Ion (Li-ion) - These cells are used to make up the batteries for cordless tools, laptops, camcorders etc. The cell voltage is normally from 3.2v to 3.7v depending on the chemistry and so they are not suitable as replacements for primary cells or other rechargeable types. These batteries have the highest energy density compared to other types.
Lead Acid Gel Batteries - These are commonly found as the backup battery in alarm panels, however they are often used in high powered torches. The nominal voltage is either 6 or 12 volts. Its important to use a proper three stage charger with these types of battery to maximize their lifespan. Also unlike other types of battery, they can be damaged if the voltage is allowed to fall below 10 volts (for a 12 volt battery) for prolonged periods. "Yuasa" is a well known manufacturer of gel batteries.
Using Rechargeables as Replacements For Non-Rechargeables
Since the voltage of a rechargeable cell is about 1.2v compared to the 1.5 volts of a non rechargeable cell, this can cause problems in some devices. A device such as a torch will work ok since there is no electronic circuitry and the torch will just run until the battery is flat. Some electronic devices have voltage monitoring circuitry which gives a low battery warning and turns off the device when the voltage falls to a certain level. Since NiMh batteries have a lower voltage, this will happen quicker resulting in lower effective duration of use on a charge. Also some equipment may not even work because of the lower voltage of these cells. Check your manual for advice.
Using "Flat" AA Batteries
When a gadget indicates that the batteries are flat, this is often because electronics or software detects that the voltage is below a threshold level sufficient to run the device. However the energy remaining is often adequate to run battery clocks for up to 6 months.
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