Rechargeable Batteries—After the Switch

Almost six months ago we made the switch to rechargeable batteries. Next month, I’ll be doing some follow up tests to see how well the battery capacity is holding up, but for this post, I thought I’d share some thoughts on how our process has been working out.

To recap, we have stopped using alkaline batteries almost completely. I say almost because I still have a few around for the odd guitar player with a dead 9v (ProTip: If your guitar takes a battery, have an extra one or three in your case, OK?), or for the occasional metronome or other device that shows up on stage unexpectedly. However, for our regular production equipment, we’re completely rechargeable.

We went with a variety of batteries in our system. For the lead pastor’s UR1M, we have two sets of Powerex AAA batteries. Those live in a dedicated 4 cell charger that charges them nice and slowly. There has yet to be a time when the “fuel gauge” on that mic drops below 4 of 5 bars on a weekend. I have a set of eight Ansmann, a set of eight Sanyo and two sets of eight Powerex cells for our UR1s and UR2s, as well as the PSM900 receiver. The AAs get more run time on a typical weekend than do the AAAs, but we’ve never had one drop down below 3 bars. I also bought a bunch of Powerex Imedions for use in our MightyBrite music stand lights. Those are LED-based lights, so the power draw is quite low. The Imedion is a 800 mah, low self-discharge design. I’ve found we can easily get three weekends of stand light use out of them before needing a recharge. We could probably go four, but if we use the same stand lights every weekend, they tend to start getting a bit dim on weekend four. Since it really doesn’t cost anything to recharge them, we do.

We’ve established a really straight-forward process for managing the batteries. I have the capacity to charge 24 AAs at once, so we leave 24 batteries on trickle charge all week. Come Saturday afternoon when we’re setting the stage, we’ll pull batteries out of the charger and load up the mics. Depending on the weekend, we’ll use between 10-18 cells. Saturday night, the monitor engineer collects the mics (and the PSM900) and puts the batteries back in the charger. We always charge using the soft charge mode, which charges at a rate of 500 mah. Sunday morning, we repeat the process. With Alkaline batteries, we would typically try to stretch the batteries for a full weekend (though, they often didn’t make it). With our current process, we may have added a few minutes worth of battery change time to our weekend routine.

For the Imedions, I have a recurring task set up in my Associate TD’s to do list every three weeks. All told, it takes about 10-15 minutes to cycle the batteries out of the lights, into the chargers and back. Since that’s only once every 3 weeks, it’s not a big cost. I have more Imedions than we actually use, so if someone leaves a light on overnight, we’re not in trouble.

A Few Observations

As expected, the batteries are working very well. In the past six months, we’ve not had a single mic go out due to batteries. In fact, none have even been close. We have Wireless Workbench set up at FOH to monitor the health of the packs, and it’s gotten to the point where I don’t even think about them anymore.

One thing we have noticed is that the AAs are a little bigger around than Alkaline cells, and that diameter varies between brands. Ansmann are the smallest, followed by Sanyo, then Powerex. The Powerex are a really tight fit in the UR1 bodypacks, and I’ve taken to using Ansmanns in those. In the UR2 handhelds, all of the cells fit, but removing the Powerex cells takes a bit of creativity. I’ve found if you pull the exposed battery out quickly, the force of the spring is enough to eject the other one enough to remove it. Go slow and you’ve got your work cut out for you.

After six months of heavy use, that’s about the only drawback we’ve found to them. Given that we’ve kept over 600 AAs and AAAs out of the landfill and saved over $250 in that time, I feel pretty good about the switch.

As I said, next month I’ll be re-testing the batteries I tested in March and we’ll see exactly how well they’re holding up. From a practical standpoint however, it’s been a great success.