Rechargeable Battery FAQ

Wow. I have noticed that a lot of people do not know anything about rechargeable batteries. This should explain it all... This is an old page I wrote and decided to roll over to the new site because it's accurate and if I spent time on it, I might as well keep it around.

Nickle Cadmium Batteries (NiCd)

These are the worst type of rechargeable batteries there could possibly be. THERE IS NO REASON THAT PEOPLE SHOULD BE USING THEM ANYMORE. THEY SHOULD BE BANNED. First of all, they are susceptible to the "memory effect" (which I will explain later because no one knows about that either). Second of all, their lifespan when they are treated properly is about a year or two. When abused, they can last six months to a year. You know that the battery is worn out when you have to charge it every day and it only lasts five minutes.

Another bad thing about these disgusting batteries is that they are terrible for the environment and no one disposes of them properly. They're heavy and have the least power out of the other types I will mention. These batteries are most commonly found in cheap cordless phones and things like that. It's a damn shame that there is no such cordless phone with a Lithium Ion battery, (but that's because they want to make money by selling you more batteries because they go bad often.) They do, however sell them with NiMH batteries (see below), and those are better.

Nickle Metal hydryde Batteries (NiMh)

These are a lot better. They are starting to gain more popularity in cordless phones and are found in some cell phones. There is a 5-10 percent chance that these batteries will be affected by the dreadful memory effect.

NiMH batteries provide the same voltage as NiCd batteries. However, they have at least 30% more battery life than NiCd batteries but take approximately 20% longer to charge. First several times that you charge your Nickel Metal Hydride battery, trickle charge (slow charge) it, this will condition the battery. Unlike Nickel Cadmium, the Nickel Metal Hydride battery can withstand random charging. Never overheat these batteries because that is the worst thing.

Lithium Ion batteries

Excellent!! No memory effect at all. Sony camcorders use these and those batteries are called "InfoLithium" because the camera can determine exactly how many more minutes are left. Smart!!! Anyway besides that you can charge these anytime you want and there shouldn't be any trouble. Of course all rechargeable batteries wear out over time but these are by far the best ones!! My phone once lasted two weeks before I had to recharge it. See what I mean.

And now... Technical stuff!!! Lithium Ion batteries are at least 30% lighter in weight, and carry at least 30% more capacity than their NiMH or NiCad counterparts. Lithium Ion batteries do require a special type of charger because of their unique charging requirements. While Lithium Ion never has a memory effect, it does prefer to be charged at a rate somewhere between conventional slow chargers and a rapid charge. The battery will accept a rapid charge, but must be slow charged the last 15% of it's charge cycle. Overheating will damage the battery and could cause a fire.

Lithium Polymer batteries

This the newest battery type being used in cell phones and are rarely used (yet). They have a higher power density than the other types. This allows manufacturers to provide either a thinner or lighter battery, or some combination of both. They are often hard to find. Lithium Polymer batteries do not suffer from the dreaded memory effect and can be recharged anytime. Go to Wikipedia to learn more.

And now... Technical stuff!!! Lithium Ion batteries are at least 30% lighter in weight, and carry at least 30% more capacity than their NiMH or NiCad counterparts. Lithium Ion batteries do require a special type of charger because of their unique charging requirements. While Lithium Ion never has a memory effect, it does prefer to be charged at a rate somewhere between conventional slow chargers and a rapid charge. The battery will accept a rapid charge, but must be slow charged the last 15% of it's charge cycle. Overheating will damage the battery and could cause a fire.

The Memory Effect (That No One Knows About)

This is kind of hard to explain so bear with me for a minute or so.

Say you just bought a cordless phone and just finished charging it for 12 hours. The phone rings and you pick it up and talk for about an hour. Pretend that this uses up 50 percent of the battery. What happens next? People put the phone back on the charging cradle - the absolute worst thing you can do and I'll explain why in a bit. I know the majority of people do this and I can't seem to convince them not to because I get a response like "What are you crazy? If I keep the phone off the charger it will run out, but if I keep putting it on, it will always be ready for me." That's true, but by doing so, your phone's battery will degrade to the point when it only lasts for five minutes, then needs an eight hour charge. Now say you put that half empty (Yes, I am a pessimist) battery back on the charger. Over time, the battery will "forget" that it has another 50 percent and even if you drain the battery, it will only charge up to 50 percent thinking that it is completely full. So if the battery life is 2 hours when it is new, after a while it will be one hour then 30 minutes etc. etc. and so on. Now this example is just a phone... You can replace the phone with any device of your preference.

Now here's the technical stuff (I'm pretty much saying the same thing but without the example... And notice how much harder it is to understand):

The property of nickel-cadmium (NiCd) batteries that causes them to lose their capacity for full recharging if they are discharged repeatedly the same amount and then recharged without overcharge before they have fully drained. (Now in English, that means that you use it a little and then recharge it to full capacity.) However, the next time you recharge that battery, it will only charge up to the part where it was last used and rechgarged from there. The term "memory effect" derives from the fact that the battery appears to have a memory for the amount of charging it can sustain. Are you with me?? If not then just follow these tips.

"Cycle" the battery every week or so. This means that you should completely drain the battery every week or so. Warning: Do not drain the battery every single time because if you fully discharge a whole battery repeatedly, then the stronger cells in the battery will "reverse" the weaker ones. The weaker ones go flat first, and then get charged backwards by the others. This is very bad for the weaker cells, and will eventually kill a battery pack. So about once a month you may use it a little then put it back on the charger.
Do not leave the battery on the charger for extended periods of time, this causes cells to "boil" and will quickly ruin a battery.
Charge the battery at room temperature.