Rechargables NiHm's vs. disposables
 

Hi anyone use rechargable batteries in thier mic's and such. I'm just thinking down the road this might be a cost cutting measure. I use rechargables on everything, including my digi still. But didn't know how they would perform in things such as my lav mic. I actually have bought a good number to start with for my equipment. I still need to buy a tester. Anyone gone down this road?

I use NiMH recgargeable AA's in my film and digital cameras and AAA's in my wireless keyboards and mice with very good lifetimes.

However, I purchased some no-name brand 9V NiMH rechargeables that have absurdly short lifetimes (around 1-2 hours only; regular batteries go for 4-8 hours) in my Sennheiser wireless gear. I don't think the batteries are running out of charge - I think the voltage in these batteries doesn't start out right at 9V and sags in a relatively short itme.

Does anyone have a 9V brand they can recommend?


Thanks

Well if something goes haywire on my batteries, it will be an Energizer brand. I'm sticking with one brand to keep track of things. I did a search and didn't see much on this topic.

Most of the pros will not use rechargables in their wireless setups. The dropout voltage is too high and your operating time is quite low.

If you want a very long life, use the LiON 9 volt batteries at around $7 each.

I really have no idea how long a 9 volt will last in a wirless setup. Could anyone tell me. I mean if I can get 2 hours or so out of it, that'll work for most things. Umm, pardon my ignorance, but what's a drop off rate for a battery?

The Sennheisers will get between 4 and 6 hours out of an alkaline cell depending on environmental factors. Each unit's user manual should tell you what the factory expects. I always drop their value by about 1/4 to be safe.

Every battery starts out fully charged at some voltage. As power is drawn from the battery, the voltage starts dropping. Some, Lead Acid, for example, droop fairly fast. Alkaline, NiCAD, NiMH, & LiON all have a more flat voltage curve until they reach exhaustion and then they drop real fast.

Most radios and cameras are set up to stop well before the battery is really fully discharged. They need a relatively high voltage to perform to specification. Especially radio transmitters.

Rechargable NiMH batteries lose much of their power within a couple of weeks, if not used within that time. For things such as mikes, remote controlers and keyboards, I always use disposable, non-rechargables. Disposable batteries have a higher actual voltage and more stored power. Rechargables in things that use small amounts of power and might
go for long periods on disposables, have a habit of failing after just a few weeks, due to the time element, not the actual power used.

If NiMH rechargables are used in cameras or bike headlights or other units that have a heavy power draw and their charge is used in just a few hours, these kinds of things are well-suited for them.

The best AA batteries I've found for mikes are non-rechargable lithium, by Eveready. One pair has lasted me for 3 years in my two big XLR mikes and they now test at 1.6 volts, after a new voltage of 1.7 volts, with a nominal voltage of 1.5. I use them for my blinking LED bike taillights and get about 750 hours from them. Most rechargables give only about 1.3 to 1.35 volts at full charge. These Eveready lithium Energizers used to cost $5. each, but now sell at 2 for $5. Perhaps they make a lithium one of the 9-volt type, as well.

I'm surprised to hear that lithium batteries only last 4 to 6 hours in a Sennheiser mike. Perhaps these are a very small, special type?

Steve McDonald

Got a mis-read there, Steve. The sentence refers to and mentions Alkaline batteries. LiONs are good for many more hours.

I've been using Tysonic NiMH 9v batteries in my Lectrosonic mics. Good for about 5 hours in the receiver and a bit more in the transmitter.

With the price of 9v batteries, these have already paid for themselves.

Got them from Thomas Distributing.

http://www.thomasdistributing.com/

Dean Sensui
Base Two Productions

Dean - Nice link! Looks like a better selection of gear is available now vs. 1+ years ago when I made my purchases.

Ron Johnson

NiMH & Wireless (radio) microphones
 

I have done some extensive testing of NiMH batteries with Sennheiser, AKG & Sony wireless mic's. The results can be viewed on my website at http://www.soundandmusicco.com/nimh.htm

Although I think rechargables are great, I see a huge amount of logic using disposables. Disposables in their orginal packaging give you a visual checklist of what 'fresh' batteries you have before you start a shoot. With very little effort, it is easier to be sure that you have enough 'charged' batteries. But hey, I am paranoid and even test my disposables for charge with a VOM before I put them in my Beachtek (phantom with preamp LOVES batteries).