What’s the deal with rechargeable batteries?
I’m in the process of replacing my Sennheiser Evolution 100 lav mic systems with the new Sennheiser Evolution 100 G3 ones (because they have diversity) and decided to revisit my battery choices.
In the past I was simply using Alkaline AA’s from Costco (Kirkland) but didn’t like the fact that I was constantly throwing them away, even if they were only 1/4 used.
So I went out and bought a bunch of Sanyo Eneloop rechargeable AA’s. If you aren’t familiar with Eneloops, they are low self-discharge NiMH rechargeable batteries. The low self-discharge part references the fact that unlike regular NiMH batteries, they hold most of their charge when stored, which is what I didn’t like about the regular rechargeable ones – I could never trust they had a full charge unless they came fresh off the charger – and I wasn’t about to add that to my prep list. This graph, from Stefanv.com, shows that after 3 weeks eneloops have more charge left than NiMH batteries. This is consistent with my past experiences with charged batteries that don’t hold a charge.
Eneloop VS NiMH graph
So initially my Eneloops seemed to work fine, although the battery remaining meter on the Sennheiser packs usually starts at only 2 out of 3 bars. So I a got to wondering if they are really a good fit. They seem to have enough life and I know that their voltage is consistent, unlike alkaline batteries where the voltage starts higher but dips lower. So in the end I think that the performance is similar, although I know not to trust the battery remaining meter as it will tell the tank is always half full and then all of a sudden it will go empty.
So I was all set to buy some more for a client of mine who has 3 sets of G3’s (= 12 batteries at a time) and I asked my local video supply and rental store their opinion as they too were switching over from Alkaline to rechargeable. They opted not to go with the Sennheiser branded ones as they require a proprietary charger and it wasn’t a good fit for their rentals. Instead they were going with hi capacity NiMH batteries from Ansmann. So I checked out their website and found that Ansmann carried both high capacity 2,850 mAh NiMH and 2,100 mAh low self discharge NiMH batteries (Max E) and that my local pros decided to go with the big numbers over the smart numbers – or so I thought.
Ansmann Max E low self-discharge rechargeable NiMH AA battery
Now here is what boggles me – the description sounds like these will be a perfect fit for wireless microphones – and then there is the ominous warning at the end:
Use these low self-discharge rechargeable batteries for remotes, cameras, hearing assistant devices, nursery pagers, wireless mouse and keyboards, guitar pedals, walkie talkies, and any electronic item where the battery is left dormant for extended periods of time.
Charge up 1000 times on any Ansmann charger
Not recommended for wireless mics and IEM’s.
So what’s the deal? Is there some compelling reason why I shouldn’t be using low self-discharge AA batteries in my wireless microphones?
I had been hesitant to use rechargeables of any kind in wireless transmitters for a long time…but, I decided to try sanyo eneloops in our Sennheisers this season and have been pleasantly surprised. I fully trust them to make it through a full musical with intermission (having batteries in place an hour before the show starts). Usually the 3 bar battery indicators still have 2 bars when I take the batteries out 4 to 4 1/2 hours after putting them in…a couple might have gone to 1 bar, but none have died. I figure even though the box says they’ll last for 1000 charges and they won’t get that many in one year, to be safe I’ll just replace them every year from here on out and give the old ones to cast members who can use them, keeping a few for myself. This is saving us $1000’s and makes me feel better…glad to not be throwing away dozens of batteries every night.
Hi Brandon – thanks for the post and for sharing your experiences. I just completed a review for EventDV Magazine on my experiences with the Sennheiser G3, rechargeable batteries, and battery chargers. Watch for it online or in the January EventDV Magazine.
For the review I tested seven battery options, including the new Ansmann Max E 2,500 NiMH low self discharge batteries. They were my top pick.
I learned a lot about the differences between the discharge curve of alkaline batteries and NiMH batteries and this difference explains why rechargeable batteries don’t appear to last as long when you look at the bar remaining indicators on the Sennheiser wireless body-packs.