Rechargeable Batteries and Radio Mics

[pdherring]

Happy New Years Eve Everyone,

 

So I thought it worth reporting on my experience with Sennheiser G3 and rechargeable batteries.

 

So coming up to panto season I decided to take the plunge with my Sennheisers and not use the 850+ AA that the show would have required. I really didnt fancy paying the stupid amount for the sennheiser packs and chargers.

 

I invested in the following:

 

Sanyo Eneloop 2500mAh

AccuPower LCD Fast Charger IQ328

Well at first I was concerned but let me tell you, these batteries are lasting over 16 hours and havnt once skipped a beat. 55 shows in and I havnt regretted what I bought once. I originally bought enough batteries for two sets so that I would do the norm and change the batteries for every show (two shows a day for panto season) After testing on the tech days this showed that the batteries would last over 16 hours with still plenty of juice left in them according to the chargers. Also one thing to point out is that these batteries are actually getting better the more cycles of charging and discharging they go through.

 

Anyway I just thought I would report this as I am sure (like me when I was researching) there will be others looking for information on what other have done and recommend.

 

Happy new years in advance to all.

 

Pete

[TonyMitchell]

That's interesting.

 

A few years ago, we tried Energiser AA rechargeables with our UHF kit and found them to be useless - batteries lasting just a couple of hours and going from fully charged to almost empty status within say ten minutes.

[pdherring]

Before the show I actually considered putting the packs into low power mode as the signal was always 100% even when the cast were not on stage but this was not required.

 

We show on WSM 3 bars from preset all the way through till almost the end of the first show. Thing is I know that the way the Sennheisers monitor the batteries is based on voltage and as rechargeable are never 1.5 volts they will drop to 2 bars quicker than a standard battery. Although my understanding is that they will stay on 2 bars much longer and then drop off quicker.

 

I can honestly say that I have no idea how long they will last but at 16 hours they were still on 2 bars and the charger the next morning only showed it having put 1500mAh of power into the flat batteries. so by my basic maths that means they still had 40% left in them.

 

I did a lot of research before taking the plunge as it was obviously not only the investment but me as a designer having to stand by what I had said to a customer. A lot of people were reconmending the Eneloop so thats why I went down that route.

 

Pete

[bruce]

Interesting

Are you charging them daily (when probably only half discharged) or are you doing full cycles?

[pdherring]

No I leave the packs on and the batteries in them over night so they get as much of a discharge as the Sennheisers will allow. Then charge from empty(Ish). The reason I got the chargers I did was because they are designed with a refresh cycle on them. I did this when the batteries were brand new as described in the manual but havnt since.

[Shez]

I was under the impression that the Sennheisers would drain every last ounce of charge from batteries before switching off - something that isn't generally recommended for rechargeables. Presumably this hasn't been a problem in practice? I guess that charger will show you what's actually left in each battery?

[pdherring]

You maybe right! I will look on Thursday when we have our next show. If I remember that is. But these batteries are NiMH so they dont mind being drained completely, infact it is actually what is reconmended as I understand. Unlike the old NiCAD that didnt like being fully discharged if I remember.

[BoogieBear]

Thank you for this Pete, what you have done was exactly what I was planning to try with 6 channels of G3s

 

Cheers

Anton

[stevefez]

Just to add that we use the Eneloop's at church. They've been abused, charged, half charged, half used and have been faultless so far. They last the full 8-10 hours we need them too. We're using them on the same systems, Senny G3s. We have enough sets so that we only need them to last 3 or 4 hours tops, but have been using a single set over a couple of services because they are lasting so long. They would probably last 3 services, but have the risk doesn't seem prudent and the timings of the services means we never need them too.

We have a few sets and they get rotated regularly, the idea being that each set getting a full drain and charge cycle every month, rather than just being 'topped up'. In practise, this seems to be working. The only time a battery has failed is when it's been entirely user error.

[bigclive]

The primary issue with over-discharging rechargeables (both NiCd and NiMh) is when more than one cell is used, as the first to go flat will be effectively reverse charged by the remaining cell/s. When it's just a single cell it goes down to near zero and that's as far as it can go.

 

Modern NiMh cells are fantastic. I use them all the time for stand-alone illuminated ornaments on a 24/7 basis. The only issue I've found is that some of the "intelligent" chargers can't handle older cells where the voltage floats high under high current charging conditions and terminate the charge far too early. In those instances the plain "dumb" chargers are slower, but will give a guaranteed charge. That said, with fresh batteries this is not really a problem. You can get chargers which give an indication of how much charge (in mAh) they applied to each cell, which is quite helpful in ensuring you know that they did get a charge.

 

The seemingly short life of rechargeables mentioned above may be down to the lower voltage of NiMh cells. They start at 1.5V and quickly drop to about 1.2V where they sit for most of their discharge. Some older or badly designed equipment may indicate the batteries are low if they do it by voltage alone, since a lot of stuff that uses alkaline cells will only work between about 1V and 1.5V which actually makes them horribly inefficient in using the actual capacity of an alkaline cell. If in doubt just put a freshly charged NiMh cell in and do a long test to see how long it lasts. In many instances the unit will show a low battery, but then run for much longer than an alkaline would have lasted anyway.

[dbuckley]

I use Eneloop batteries for props, with a La Crosse charger that also has a refresh mode. So the Eneloops sit in a box for months between shows, a couple of weeks before the show they spend a week in the charger in refresh mode, They then get misused to hell with high discharge currents and go in the charger between shows. Can't praise these cells enough. The charger is also really good, it's a USA beastie from Amazon, but it has a niversally power supply.

[bigclive]

I've got a LaCrosse charger too. Is your as fickle as mine? The buttons are very laggy for selecting cells and changing between modes with sometimes rather random results. I also had an issue with the reliability of the input jack connector on the charger not really handling the high current from the PSU well.

[dbuckley]

Mine is "ok", it's sometimes a struggle to get it to the mode I want, the buttons are a bit "loose". However, I only use standard charge, and refresh, with other settings left on default, so maybe I've not plumbed the same depths of configuration as you may have...

[pdherring]

I agree with the comment about the only failure having been user error.

 

I obviously wasnt paying attention one day when doing a change and when I check WSM the mic was showing as dead. When I went to the chargers two cells were showing as full so that was simple. I had put two pre charged batteries back in the chargers and put flat ones into the mic.

 

Defo my fault and not the batteries or chargers.

 

Now we are at the end of the run I can totally say if for nothing else than only doing one battery change a day, these batteries were worth every penny.

[Solstace]

Worth chiming in with my experience too, a slightly different take on the same thing.

 

We have 8 sets of Sennheiser G3 (EW100 series), and matching L2015 charger cradles. These will only work with the BA2015 packs. We went this route because we're a church, and therefore simplifying infrastructure to the "nth degree" becomes something of a priority. We moved to this system from conventional rechargeable high-capacity NiMH AA's, mostly providing more convenience to untrained end-users. In the first year or so of use, we've had to swap out two BA2015 packs on warranty because they kept giving "error" warnings and not charging.

 

Our experience has been largely positive, since users can see at-a-glance whether or not the pack they're about to pick up is charged, and the cradles create a lovely storage area for the mics/packs. The caveats however have been:

• BA2015 packs give us about 6 hours of useful life, compared with more like 10-12 hours from Varta NiMH AA's used with an appropriate rack-mount charger.
  
• People often don't put the packs/mics back in the cradles properly, resulting in at least one set of flat batteries the next time the mics are required.
  
• Even when the packs/mics are inserted correctly, we get random "error" status occuring on the charger, on average one will go every week, regardless of the condition mic/beltpack/battery-pack correctly inserted. Not cool and again, tends to lead to at least one mic not being fully charged when it's needed.
  

 

We therefore keep a stock of Alkaline AA's hanging around for absolute emergencies, but in our usage patterns it's fairly unusual for all 8 sets to be in use at once, and a few of us on the staff generally keep an eye out for charger errors during the week to prevent the majority of "gotcha's" that will get us on weekends when the mics are most in demand.

 

So it's not absolutely ideal, but it's workable as a "managed" alternative to alkalines, but without the potential battery-life available from high-capacity AA rechargeables that have been on the market for a while now.

 

Hope that helps someone!