Whether you are a gadget geek or just someone that uses a ton of batteries, it doesn’t take long to realise that investing in several sets of NiMH rechargeable batteries will save you tons of money over the long term. Though rechargeable batteries tend to cost a bit more up-front, their lifecycle far outlasts that of even the most premium disposable alkaline batteries. What’s more, NiMH rechargeable batteries are significantly less damaging to the environment: nickel, the main ingredient in NiMH rechargeable batteries, is easy to mine, plentiful, and much less toxic when disposed of than alkaline batteries or the old NiCD recheargable batteries. When you do the research, NiMH rechargeable batteries seem like the “holy grail” of modern battery technology. But as you know, in life there is always a catch.
With some rechargeable batteries, their Achilles heel is depression. That’s right – your rechargeables can eventually suffer from “voltage depression,” otherwise known as “memory effect.”
Why Rechargeable Batteries Become Depressed.
A wise man once said, “The light that burns twice as bright, burns half as long.” (Actually, that quote is from Blade Runner. Sorry, Confucius.) This is the case for your old Duracells or Energizers. They perform well until the very moment of their death. Rechargeable batteries, however, exhibit a more “human” life cycle. Memory effect is said to occur in some rechargeable batteries when they are not fully discharged between charge cycles. Half empty, half full conditions cause the batteries to “remember” the shortened cycle and are thus reduced in capacity (length of use per charge).
This problem was very common with rechargeable batteries up until about 5 years ago. In fact, Voltage Depression occurs primarily in NiCad batteries. NiMH batteries are almost never affected and Li-Ion batteries, the highest quality and most expensive rechargeable battery option, are NEVER affected.
There’s light at the end of the tunnel for your depressed batteries.
There is hope for your vanquished Vapexes and sad Sanyo Eneloops, however. Improvements in NiMH battery and charging technology has closed the gap in this flaw, and ‘memory effect’ is becoming a thing of the past. In fact, Voltage Depression is more a problem with incorrect charging than a battery problem. This is why investing in a high quality battery charger is as much a part of the rechargeable battery process as the batteries themselves. Now, “smart chargers” analyze and charge each battery individually, meaning that each gets a custom charge that restores them to their optimum performance. Because of smart chargers like this, Voltage Depression does not necessarily permanently damage a battery. It can most likely be corrected by fully charging and discharging the battery. In fact, quite often what people perceive as Voltage depression is no more than a poorly charged battery.
A few steps to keep your rechargeable batteries happy.
1. Invest in a good charger. NiMH batteries should not be charged in a NiCad charger, unless the charger is specifically made for both chemistries. If you have solar powered lights or a cordless phone that uses NiCad batteries DO NOT replace them with NiMH batteries as they can overheat or even explode. There are cheap chargers and there are expensive chargers. Make sure the charger you get has good reviews and is well made. Smart chargers with delta v microprocessor control chips are usually the best choice.
2. When charging your batteries, occasionally discharge them fully before recharging them. This is especially helpful to NiCad batteries. Be careful not to discharge too deeply (Less than 1v per cell for NiCad and NiMH. E.g., a 3.6v pack to no less than 3v). Discharging to absolute zero will make your rechargeable batteries useless. It’s best if you have a charger with a conditioner that will cycle the battery for you.
3. Be sure to store your batteries properly. Do not leave your batteries in a hot car, or in humid conditions. The best storage conditions are a cool, dry place. The refrigerator is fine if you stick in a packet of silica gel with your batteries in a sealed bag to keep them dry. It is a good idea to charge your NiCad or NiMH batteries fully before use if they have been in storage.
4. Most cordless phones use NiCad batteries. To maximize your cordless phone battery life, make sure to leave your phone off the base every once in a while until it is dead. Then leave it on the base until it is fully charged. You should leave your phone on the base for at least 24 hours to charge it fully.
There is no need to avoid rechargeable batteries. They can save you significant amounts of money over time. Don’t be scared off by the ‘memory effect’. Even if it occurs with your rechargeable batteries, it is easily manageable and correctable.
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