Batteries for Wireless: Rechargeable vs Single Use

Batteries, Maths & Landfill

When it comes to the best way to power your wireless systems – alkaline battery or rechargeable – there are many factors to consider. Let’s dive into a few in an attempt to un-muddy the waters.

Less is more

Much as we want to cut straight to the heart of it all, we’re not talking about quantities of batteries and waste with this particular “less-is-more”. Rather, let us look at the wireless microphone system that gets used for just three performances and then put back in the cupboard until next year. Less performances equal more risk of battery leakage inside the wireless transmitter.

The risk of battery leakage from a nickel metal hydride (NiMH) rechargeable battery is negligible, even if left inside a device for a prolonged period.

How much landfill is acceptable?

Here is where ‘death by a thousand cuts’ really comes to the fore, when we look at all productions as one.

Let’s firstly imagine a typical user of wireless microphones – the annual school production. A small-to-medium sized production, with a handful of shows and a couple of tech rehearsals will consume, let’s say, 140 batteries for the entire production.

Of course, there are around 8000 primary, secondary and combined schools in Australia. If we imagining that just 15% of these schools attempt an annual production, it blows that figure out to 168,000 batteries for ‘one’ production in Australian schools. Add to that a few end-of-year concerts, and it would be a very conservative estimate of 250,000 batteries heading to landfill annually.

Incredibly, this already under-estimated figure doesn’t include amateur theatre, professional productions, theatre restaurants, nor the thousands of bands that use the same wireless systems and in-ear-monitoring systems on a weekly basis.

Brand-specific rechargeable batteries

If you are the person responsible for ensuring the wireless microphones are ready for action at any time, the very first thing you’ll notice is how quickly the pile of alkaline (single use) AA batteries disappears. Should it seem to be far more quickly than your wireless system use indicates, that might be because the AA batteries have been ‘borrowed’ by students and co-workers, as they fit a variety of devices – not just wireless systems.

Generic rechargeable AA batteries offer the ‘double-whammy’ of not only being desirable to the above-mentioned borrower, they also may not deliver the (approximately) 1.2v per cell, consistently throughout the charged state. Once your battery level drops, although the wireless will remain on, the actual RF performance – the quality of the wireless transmission – will suffer greatly, leading to dropouts and possible interference.

The safety net and convenience factor

With single-use Alkaline batteries giving us a landfill concern, and generic rechargeable batteries possibly not performing ‘up to scratch’ (side note; some are better than others); there are already some great reasons to choose wireless-specific rechargeables (such as BA2015 for Sennheiser, or SB900A for Shure).

For example, if you load your BA2015 into the Sennheiser bodypack, then drop it into the L2015 charger after the gig, it simply will not over-charge. Similarly, if you put the bodypack into the charger without the correct BA2015 battery in place, it won’t charge. The safety nets are in place to ensure there is no danger of damage.

With a lifecycle of around 1000 discharge / charge cycles, using the correct NiMH rechargeable battery pack in the wireless transmitter, the battery is highly likely to last for the same number of performances as the wireless itself. Smart RF (wireless) technicians will not only keep a spare rechargeable battery for each wireless device (one to use, one to charge), they will also find a way to document the life of each battery. Get ready to buy another one after around 800 charges.

If all theatres and performance venues around the world approach battery usage the same way, imagine how much less landfill we contribute each and every year.

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