Rechargeable Batteries: Year 2

Battery-graph-1-year-later.jpg

These were the results of the 1-year test.

OK, the title of this post might be a little misleading. I had actually indented to do multi-year tests to see how the rechargeable batteries in heavy rotation would hold up over the years. However, the answer is this; not quite as well as I had hoped. In fact, we got about 22 months out of the batteries before they were not performing to level that I was comfortable with. To be fair, some of the batteries are still going strong, but others have thrown in the towel. So I’ve replaced my entire stock.

And right away, all the naysayers will jump in and say, “Ha! I told you rechargeables were a bad idea!” Not so fast, cowboy. I’ll come back to that in a minute; first let me lay out the timeline. 

In January of 2010, I started buying chargers and batteries. By March, we had switched over completely to rechargeable batteries, which is also when I did my first round of tests. Those batteries were used every weekend and at mid-week, and as a group, performed exceptionally well. We did have one or two cells go bad, and those were replaced. Those cells got us through Easter, Christmas, and another Easter, not to mention outside events and other special services. 

Last fall, I started noticing that some of the cells began to drop off in capacity. I never had a mic die during a service, but I started seeing them drop down lower than I was comfortable with. Some batteries would end the second service on Sunday at 1 bar, which I didn’t like. I marked those batteries, tried re-conditioning them, but eventually decided that it was time to replace them. So in late November, I ordered a new set of 32 batteries and retired the old ones. 

Now, let’s do some math. We used the original batteries for about 22 months. We used to go through approximately 36 ProCells a week between weekends and mid-week. So here’s how it breaks down:

22 Months = 95 Weekends/Mid-Week (weeks)

95 Weeks x 36 batteries/week = 3,420 Batteries (if we used ProCells)

3,420 batteries x $0.32/ea = $1,094.40

So, if we had stuck with ProCells, we would have used roughly $1,000 worth of disposable batteries in that time frame. When I bought new batteries in November, I spent about $120 including shipping. Now it’s true I do have a few hundred dollars in charger cost, plus the original set of batteries. But on the high side, I’ve spent less than $500 on everything including chargers in the last 2 years. And now that the chargers are paid for, I can plan on about $120 in new batteries every two budget years.

But wait, there’s more! We also use AAA powered LED music stand lights every week. We have about a dozen of them in rotation, and we typically use about 6 on any given weekend. Those take 3 AAAs apiece. I also switched those over to rechargeable batteries about the same time. Only with those, I use low self-discharge (Ansmann Max-E) batteries so they don’t need to live on the charger all week. Let’s do some more math.

6 Stand Lights/week x 3 AAAs x 95 weeks = 1,710 AAA batteries

1,710 AAAs x $0.39 = $666.90 (I knew disposables were evil!)

Now there’s another $550 or so in savings (I have about $100 in Max-E AAAs). And those batteries are still going strong. I found that I can get about 3 weekends worth of service from those batteries in those lights. So, every three weeks, I pull my AAs out of the chargers, and charge up the AAAs. It takes about 10 minutes of my time, and we save $500/year. Not too bad. 

And this doesn’t count the community room, which I’ve also switched to rechargeable batteries. There is an event using a wireless mic over there almost every day, and they are on the same set of batteries they’ve had for nearly two years. Because the event times are shorter, a decrease in run time hasn’t been as big of a deal. Still, I may have to drop another $25 and get a new set of 8 AAs over there in the next month or so.

Earlier I mentioned that the performance was dropping off past where I was comfortable. I’m often asked, “When do you replace the rechargeable batteries?” The answer for me is, when I’m not comfortable any more. If I start seeing the cells drop down below 2 bars regularly after a service (when they used to hold at 4), it’s time to swap them out. Basically I’m replacing my rechargeable batteries when their weekly performance drops just below the level of a ProCell. 

How long that takes for you will depend on how you use them. I know people who use them far more often than I do, who will have to replace them more often, but when you do the math, you still come out way ahead.

Remember, those ProCells were going in the trash when they got down to 2-3 bars. With a rechargeable, you throw it on the charger. So it still works out. 

If you’re still on the fence, I encourage you to do the math. Figure out what you are really using now, and what the payback is. I can almost guarantee you the result will be savings when you switch. And we already know that rechargeables in good condition will outlast ProCells anyway by 30-50% and at end of life they are still on par; so there is really nothing to loose.

Next week, I’ll share my current strategies for (hopefully) lengthening the life of my rechargeable batteries.

Have you made the switch yet? If so, what is your experience? If not, what are you waiting for?

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