Rechargeable batteries are everywhere these days: cordless tools, laptop computers, cordless phones, and cell phones, just to name a few. What is more, the pesky things are always wearing out, not taking a charge, or running down in a very short time.
This article explain how to how to take care of rechargeable batteries them to make them last longer, how to test one to see if it can be reconditioned, how to recondition rechargeable batteries for electronic devices.
Types of Rechargeable Batteries
There are three types of rechargeable batteries. Although these batteries will not look much different from the outside, there are significant differences among them:
- nickel cadmium (Ni-Cd): The second oldest of battery types we cover in this book. They are the oldest battery type that we use that suffers from the digital memory effect. Recent developments with nickel-metal hydride (Ni-MH) and lithium-ion (Li-Ion) batteries have rivaled the cost effectiveness by lifespan of this battery. However they are still used more often than other battery types when a very high discharge rate is required
- nickel metal hydride (NiMH): are a newer development than and very similar to Ni-Cd batteries.
- lithium ion (Li-Ion): are the most recent of the three mentioned battery types to be commercially available.
Tips to Prolong the Life of NiCd or NiMh Batteries
- Do not leave a nickel-based battery (Ni-Cad & Ni-MH) in a charger for more than a day after full charge is reached – This will result in overcharging and that is bad for your battery’s longevity.
- Apply a monthly full discharge cycle. Running the battery down in the equipment may do this sufficiently -This exercises the battery which helps prevent the “memory effect”.
- Do not discharge the battery before each recharge – This would put undue stress on the battery.
- Avoid elevated temperature – A charger should only raise the battery temperature for a short time at full charge, and then the battery should cool off – Room temperature is ideal.
Tips to Prolong the Life of Lithium-based Batteries
- Charge the Li-ion often, except before a long storage. Avoid repeated deep discharges.
- Keep the Li-ion battery cool. Prevent storage in a hot car. Never freeze a battery.
- If your laptop is capable of running without a battery and fixed power is used most of the time, remove the battery and store it in a cool place.
- Avoid purchasing spare Li-ion batteries for later use. Observe manufacturing date when purchasing. Do not buy old stock, even if sold at clearance prices.
Why Rechargeable Batteries Need to be Reconditioned?
Rechargeable batteries do not last forever. There are only so many times that you can charge and recharge them. First they start to lose power and you find that there is less and less usable time that you have before you must charge again. Some people have termed this the memory effect.
The term “memory” basically is described as the battery “remembers” its usual discharge point and superficially “needs” a charge whenever it hits that point. In other words, if you have a NiCd that always gets discharged to only 50% of its capacity, it will eventually not run below that 50% mark if you ever wanted to discharge it to a lower point.
In a new NiCd battery the active cadmium is present in finely divided crystals. The memory effect develops as these crystals grow and reduce the effective surface area of the cadmium.
This results in voltage depression which leads to a loss in capacity. Advanced crystal formation can lead to sharp edges piercing the separator between the plates and causing a high self discharge rate or an electrical short.
Many people who do not know about this effect just throw away the battery because they think it is dead. More than likely, the battery can be revived providing that the battery isn’t completely damaged.
Basically rejuvenation and reconditioning of the batteries can break down this crystal formation as long as they are not so ingrained from years of memory buildup. NiMh is also affected by this memory condition but not as pronounced. So these procedures can apply to them as well.
Lithium and lead based batteries do not suffer from the memory effect but plate oxidation on the lithium and sulfation and corrosion on the lead acid systems cause reduced charge capacity as well.
Reconditioning Your Rechargeable Batteries
Reconditioning a rechargeable battery is basically just taking it through a deep discharge cycle. The simplest way to do this is just to use the device until it shuts off or doesn’t operate any longer. For a power tool, it should be run without putting a load on it at the end of the discharge cycle. Then just charge it up completely again.
This process can be repeated up to two more times if necessary. If the battery hasn’t come back to good condition after that, you may try rejuvenating it. If that doesn’t help, the battery is no good.
In addition to simply taking the battery through a deep discharge cycle, there are two ways of reconditioning a battery in a more controlled way.