We photographers love rechargeable batteries for our flashes, our cameras and all the other electronic widgets. The current favorite type of battery is called a Nickel Metal Hydride or NiMH for short. These cells have decent power ratings nowdays and can withstand some abuse like fast charging them instead of a slow charge. But they wont keep a charge well, they will self discharge due to internal resistance so after several weeks of storage, you may find the cells only have half their charge.
There are many manufacturers of NiMH cells and they come in all kinds of ratings, 2000mAh, 2300mAh and 2700mAh. They come in less but we are not interested at all in those for what we need them for. There are a couple of things that will make a very large difference in how well the cell works for you. One is the actual size of the cell. I have some Tenergy cells that work ok but do not quite measure up size wise. They are a bit short and a bit fat so they do not work in some tight battery compartments. Pretty damn frustrating at times. I used to buy Duracell 2350mAh cells but I found that they have a very high internal resistance and will self discharge the fastest to flat quicker than any other cell I have.. like in just a couple of weeks. They do not seem to hold up as well even fully charged in my SB800s.
My last favorite cell were the Energizer 2450mAh cells. They held a charge for a decent amount of time and they lasted pretty well under load. But my new favorites are the Eneloops from Sanyo. These are a “pre-charged” cell but most importantly, they hold the charge for something like a full year. And the prices are very close to the classic NiMH cells. And they fit everything I’ve tried them in. But you have to be very careful in buying “precharged” cells. There are only a couple of manufacturers of them and while the Sanyos are good, the cheaper imports from China are not nearly as good. You can not go by brand name either, I’ve seen both Japanese cells (Sanyo) and Chinese cells in the same brand packaging. One guide is to look at the top of the cell, the Sanyos are white, the others are black. A fellow blogger (stefanv.com) has done some really nice work on imperical testing of Sanyo’s Eneloops. You should drop by and read his article on it.
A good charger is a requirement to keep your cells healthy and not burned out at an early age. I use a 8 cell charger (Maha’s Ultimate Professional Charger) and a 4 cell LaCross unit (LaCrosse Technology BC-900) and both work very well. I like the LaCross better and really wish it had eight slots instead of the four. At the miminum you need a “smart” charger, not one of the those stupid wall wart fast chargers which will cook your battery in 15 minutes and kill off the battery. Both of the mentioned chargers have options for a “fast” one hour charge and a two house slow charge and trickle charge. Both also offer reconditioning of the batteries which can revive a marginal cell.
A favorite shop to buy my batteries and chargers from is called Thomas Distributing. They offer all kinds of batteries, chargers, battery packs and more.
And speaking of recharging batteries and charades, bad karma goes to Engerizer and the stupid bunny for shafting consumers on their NiMH D cell batteries. They charge a premium for the D cell but in reality, it’s a repackaged AA in a plastic form to make it look and fit like a D cell. The folks at Naturalnews.com did a autopsy on a D cell and sawed it open to prove the accusation. So if you need the bigger batteries, look at Powerex for your needs. Their AAs are also a highly regarded NiMH cell so you would not go wrong with either.