Rechargeable Batteries: What you need to know

Almost all of us out there have gadgets that run on batteries.  Whether it be a wireless mouse, a flashlight, a radio, or something else.  While a lot of our battery operated tech now use proprietary lithium ion blocks that only fit that device there are still a lot of electronic gizmo's out there which still take good old AAA, AA, C, or D cells.  Alkaline batteries have fallen in price to the point where you can buy a big block of them for $10, but with the whole green push we're all starting to feel it's worth taking a look at rechargeable batteries.

Now I know what most people think about rechargeable batteries.  I recently decided to give them another shot due to all the batteries I'm buying for my game system controllers, remotes, toothbrush, and wireless mouse.  I had held out until now to switch from cheap alkaline because back in college I tried the Rechargeable Alkaline.  While I did get enough uses out of each battery to make them more cost efficient than standard batteries at the time the reliability was terrible.  I felt like I was charging the cells every other day and barely getting any time out of them.  On top of that if the batteries were exposed to freezing temperatures even fully charged batteries would die, and die permanently.  Even new batteries if frozen would be permanently dead and could not be recharged.  Needless to say this technology did not remain on the market long here in Michigan.


Now rechargeable batteries are making a big comeback.  We already use them in our phones and various other devices, we just don't seem to think about them for devices that take traditional batteries.  Well we sort of do.  Case in point anyone who has a Wii or a Xbox 360 knows that the controllers use batteries.  Many of us buy an additional play and charge kit or proprietary rechargeable battery to use with the remote.  These are handy, but for the price you could buy a traditional battery charger and rechargeable AA's.  Not only will you have a charged controller, but you'll have batteries that can be used in anything and you don't have to hunt down special batteries to work with your charger later as you add controllers (People who've added a 3rd or 4th controller to a Wii should know this pain).

So after my last experience I decided to do some research before going out and investing into any particular battery technology.  Here are the types of rechargeable on the market right now.

1. Rechargeable Alkaline:  Yes these are still on the market.  Rayovac gave these a try in the 90's, and after having them fail on the market wisely decided to kill the line.  The draw of these is that they deliver a higher voltage than most other rechargeable battery technologies out there and will work in devices that specify not to use rechargeable batteries.  The only thing here is that there are very few devices on that market now that specify this.  Flashlights and camera flashes are pretty much the only devices that benefit from a higher cell voltage.  For these devices there are better technologies on the market.
• Pro:  Higher cell voltage
• Con:  Limited life cycles.  50-500 charges per battery depending on how you treat them.  The total storage does decrease over time per charge rather quickly.  Current batteries may have overcome the temperature short comes of earlier models, but I personally won't invest in the tech to test them out.  
• Suggestion:  If you really need a higher cell voltage for a device that says it won't work with a rechargeable battery look at the NiZn battery technology.
2. NiCad:  Not going to say much here.  One of the earliest rechargeable battery technologies out there for small cells.  Does develop a memory effect if you don't use the total capacity of the battery.  Useful in the 80's, now there are much better technologies out there.
• Pro: erm... Many chargers that can charge NiCad are able to charge NiMh?
• Cons:  Too numerous to list.  I don't care if someone gives you a set of these.  Recycle them and go straight to a NiMh formula.  Check if the charger they give you is universal before you recycle it though...
• Recommendation:  Skip
3. Lithium Ion:  One of the two major techs you've probably heard of now.  Currently used in all portable electronics, cars, etc.  The formula is excellent, but expensive and difficult to find in traditional size forms.  For a standard battery you're better off currently going with Hybrid NiMh.
• Pros:  High capacity, high voltage, excellent life
• Cons:  Difficult to find.  Requires special charger.  Expensive.
• Recommendation:  For traditional battery sizes you're better off with Hybrid  NiMh.
4. NiZn:  One of the newer battery chemistries.  These provide the higher voltage of Alkaline batteries, but they provide the constant voltage over time associated with NiMh batteries.  They have a very low internal resistance meaning they charge quickly and can be used in high power applications like professional camera flashes.  
• Pros:  All the benefits of a Alkaline battery's voltage with the power curve of a NiMh.
• Cons:  Only available in AA size.  
• Recommendation:  These are great for the 5% of devices that absolutely require a Alkaline battery.  
5. NiMh:  One of the two major techs you've probably heard of now.  The other being Lithium Ion.  NiMh came about in the 90's and was widely used in Laptops, phones, cars (the EV1 used NiMh batteries, the Prius still does), and many other locations.  The technology is still around and new capacities are coming out all the time.  A Quick note:  When you get a Wii / Xbox 360 controller rechargeable battery pack this is the kind of battery in it.  Usually these are not the largest batteries on the market so loose rechargeable AA's should last longer than the pack.
• Pros:  Available in all common sizes including 9V squares (honestly who still uses these outside of clocks and smoke detectors?  Don't use these in your smoke detector!).  Sizes are ever increasing and due to the way they produce voltage over time they have far more available voltage to your device than a standard disposable battery.  
• Cons:  Self discharge.  You know how people say that they always find their devices with rechargeable batteries are in need of a charge?  Things like remotes, flashlights, radios, etc you leave in a drawer until needed and when you turn them on they're almost dead?  This is the culprit.  These batteries loose 25% of their charge over a month just sitting there.  
• Recommendation:  Don't write NiMh off just yet.  I wouldn't buy new standard NiMh cells, but if you have a charger hold onto it!  Look at the new LSD (Low Self Discharge) NiMh cells!
6. LSD NiMh:  A new twist on NiMh batteries.  These work just like the old NiMh batteries without the huge loss of charge over time.  The neat thing about these is that they use standard NiMh chargers.  So if you already have a NiMh charger you only need the new batteries.  You loose a little total charge storage vs a standard NiMh, but the difference is minimal.  They still provide more usable voltage than a disposable cell.
• Pros:  Basically these are the perfect replacement for disposable batteries for 95% of your power hungry devices.  Rayovac has a great package with 2 AA, 2AAA, and a over night charger for $10 you can get to try these out for yourself.  If you like the technology pick up a bulk pack of the Tenergy LSD batteries and a larger quick charger.
• Cons:  All the common battery companies have different names for this technology making it hard to purchase in stores.  Honestly what is the problem in standardizing this?  Yes calling them LSD NiMh might wind up causing some druggie idiots buying them up in bulk for a while but for the standard consumer it would be a real boon.  
• Recommendation:  Definitely pick these up.  Far cheaper than even disposable batteries over the long run.  Bulk packs are pretty competitive with disposables and the life cycles are in the 1000's of charges per cell.  Spend a little more now and you'll not need new batteries for years.  When looking for this type of battery you need to know the brand names.  Rayovac and Duracel call these 'Precharged Rechargeables' while Tenergy uses 'LSD'.  I recommend the Rayovac charger if you want to try these out, and then the Tenergy charger and batteries if you decide you want to stick with it.  A quick note about cheap chargers.  Small quick chargers are fine as long as you remember to unplug them.  Most don't have 'Smart' charging functionality where they stop charging when the battery is full.  Do look for small chargers with this function!  It's worth the extra money for one.  The rayovac charger below does not have this, but it's essentially a $4 charger.  If you decide you like your batteries get the Tenergy station and keep the Rayovac charger for when you're on the road!

As for chargers, you will need one.  NiZn is unique enough I would recommend buying the charger that comes with the batteries.  While the universal charger I recommend may charge NiZn, it's more of an "At your own risk" scenario.

For NiCad, Lithium, and NiMh batteries I've switched completely over to a Foxnovo 4S.  It not only charges various types of batteries, it does so uniquely to each battery.  Unlike other chargers where you may have to pair individual cells this intelligently charges each cell independent of the rest, and does not over charge a cell.  Once done it beeps to let you know when each cell is finished.

  

So here are my recommended technologies:

For Hybrid NiMh:

For NiZn:


For a Charger: