Rechargeable Batteries

[Rick Gentry]

Howdy. 

I have been going through a lot of 9V and AA batteries lately, and am thinking about setting up a recharging station. My pedal board and other necessary tools at the bench usually get plugged in. 

Do the small batteries behave like the big ones- get a memory after a few charges? Is the quality of the charge worth it? 

rg

[FRANK]

try nicads

[Pierre-Antoine Roiron]

Rechargeable batteries made a lot of progress these last years. Some of my customers use 9V Li rechargeable batteries without any problems. NiCad batteries have memory problems, not Li ones. On top of this, most of the time, musical equipment are not current greedy (is that correct english?), so that using batteries or rechargeable ones is not a problem.

[Russell Vance]

Putting on my sound engineer/guitar tech hat I have the following (general) experience which is directed at stage/recording operations. You can use any old thing quietly strumming away in the lounge room and nobody will complain when the battery fizzes out.

Wireless mikes ( not the receivers) are the heaviest users of available battery power and need constant current flow/pegged voltage until near dead (ie: gradual degradation of voltage is unacceptable). NiCads/Lithium minimum.

Pedal units (Boss etc) are usually very sensitive to inadequate power sources and run best with discrete regulated power systems which have a separate internal strip for each outlet ( this also reduces the noise in these systems remarkably). But, NiCads and Lithium batteries are perfectly suitable in this situation. Note: some vintage pedal units actually get their sound from having crap batteries and the accompanying voltage sag which contributes to the early breakup and distortion characteristics of these units - some modern regulated power supplies have a 'sag' function which allows the user to drop (sag) the voltage to get the sweet spot.

Daisy chains (multi connector leads with one AC 'wall wart' output splitting into many outputs ) reflect system noise throughout all the units connected and cause lotsa problems when loaded up together).

Active pickup systems, including 18V bass are definitely NiCad minimum requirement as are the Fishman/Martin Acoustic pickups.

Typical rechargeable batteries in use do not have the high constant current/steady voltage required to deliver clean power and sufficient headroom for the high dynamic range associated with musical instruments in the live environment.

There are of course exceptions and systems which don't comply with this general view but for the main the above is what I know. Rusty.

[Rob Mercure]

Rick,

Generally I think that Rusty has covered the subject pretty well but I'd like to add just a few additional comments. First off if you've using a lot of batteries I'd examine your useage patterns since many effect, etc, require that you unplug the batteries to turn the power off an I've found that many musicans just consider doing so too much bother. Still would you rather have the "bother" or a dead battery during a song on stage? And much depends on levels of technical ability - not just electronics background but also the ability to modify units and do precision soldering, etc. If you've got these skills good, if not its really worth seeking out a tech who's trained himself to do so. I've worked with lots of other electronics techs, unfortunately had to supervise some, who while being good at repairs weren't creative enough for modifications.

One modification is to change the power switching from the jack switch to a tiny toggle switch to save battery life. Another is, as suggested, to change the battery type but I'd suggest going to lithium ion instead of nicad as the discharge characterstics are more suited for signal level equipment rather than power level requirements (exceptions as noted by Rusty). Since cell phones are so obnoxiously ubiquituous the 3.7V lithium cells are commonly and cheaply avialable surplus and I just scrapped an old cell phone last night intending to use to battery for this purposes. Recently I mentioned All Electronics as a souce of 100K pots to someone on this forum and they also have truly wide selection of surplus batteries and chargers and such ("surplus" is usually new but unneeded so you aren'r buying something worthless just not needed anymore by the manufacturer) - I'd check 'em out.

One area where I "semi" disagree with Rusty is distortion characteristics from depleted batteries. In my experience and experimentation this is over rated and largely due to the obsessive/complusive theories of Eric Johnson - a great guitarist but more technically aligned with some of the HiFi "voodoo" technical theories than reality. "Sag" really only comes into play when the unit is drawing maximum curent and the current supply - whether battery or power supply - can't meet those needs. "Sag" can easily be simulated using a fixed supply and either a fixed resistor or a variable one that mimics supplies whose "sag" isn't linear (one needs a good multichannel 'scope for the experimental set up). During the late 1990s I did a series of "single blind" experiments with area musicians where I either changed components or parameters or told the musicians I was doing so and almost every time when I told them that I'd changed something - even when I didn't - they told me they detected a change. Mostly I was testing various tubes and speakers but I also did some experiments with amplifier power supplies and a few pedals (a "Ratt" a couple of Ibanez including a Tube Screamer and a vintage Wahwah reputed to be one of the ones that Hendrix liked are what I remember but there were some more - I've probably still got the noted in my dusty musty filing cabinets that I occasionally revisit just for yucchs - I'm a lot less obsessive/compulsive myself over a decade later ). Basically I'm stating that musician's "lore" should be taken with a cow block of salt!

One thing I think that Rusty was getting at that I heartily agree with is the necessity of designing the overall power supply sustem carefully to get the best life and use but some one who understands equipment. Most of us have (had in my case) pedal boards, etc, that grew "organically" by bits and pieces and that weren't engineered functionally. But once you've gotten a good handle on what you like and don't like it's really worth taking a few hours/days with a pad and pencil and calculator and determine what you need and how to most efficiently put it together. Really saves headaches on stage and when you get used to the set up you'll usually find that it's "friendlier" than the old system. That said it's still a good idea to simplify as much as possible (Murphy rules the universe - or thermodynamics if you want to please your physicist friends) and there are long life industrial type 9V and A, AA, AAA, C, and D cells available if you want to be lazy about it - I've found the industiral 9V batteries necessary in my Fluke DMMs to prevent the batteries going "flat" - as the British say - at inconvient moments when I'm trying to measure a 500 VDC supply in a chassis that I'm balancing on my lap cuz I'm having to do an emergency stage repair for a friend who's ignored my advice to have me overhaul the amp for several years 9not kidding, it's happened more than once).

Hope this mess helps.

Rob

[Russell Vance]

It's not a mess - it's just like having a mad auntie locked in the attic that we don't talk about because nobody believes that such seemingly simple things can cause so much work and difficulty.

The sag I refer to is a dial-in function of one of the strips on some power supplies we use and is provided to drop power to all devices - the main reference to this in the literature is the old noisy germanium tranny units from the late sixties but as I don't use them don't know whether it works or not.

But, interestingly (to me anyway) , my Mesa Stilletto II amp has a bold and spongy switch which sags the HT voltage (fixed variac type of thing) - it doesn't do a great deal until it gets loud but the other day I was working with a Carvin hollow body with low impedance pickups and the difference at all levels was most noticeable - and I'm starting to think modern amps may be a lot more responsive to front end impedance changes than those of old which may account for the problems hooking up which pedal configurations to go in the front end as opposed to the effects loop (all the standard protocols aside). But, it's been a long day and thanks Rob for penning you enlightening advice.

[Rick Gentry]

I have a Voodoo Labs power source on my pedal board that has a sag feature. A friend told me to hook it up to the wah or the distortion to imitate a dying battery, but as you can see, I have a variety of tonal choices that do not require that function.

This is an excellent and informative thread. Thanks everybody. I used some of the noise/ power stuff this morning mixing sound at church.

[Rob Mercure]

Rusty,

Thanks - I think - ah the joys of crankpotism! Anyhoo "sag" should only work when a device is pulling all the current it should udderwise the power source would have to be able to determine at what level the device is running and you're getting heavily into essentially a computer controlled feedback loop and migh as well just use one of the "modelling" amps.

You just hit on one of the real, IMHO, differences in equipment and it is the germamium transistor vs. silicon. There is a very real, very measurable effect of the transistor leakage primarily caused by the early imperfections in growing pure crystals and being able precisly junction dope them but the junction barrier volrage also comes into of effect as even the very best ge. device exibits less linearity at certain thesholds. This is why I carefully salvage these transistors from old equipment when I scrap 'em and even then only about 1/3 aren't too leaky for stomp box use - luckily I also have acquired a few new in the box over the years from defunct service shops and have sold some on e-beast for nicely userous prices . How well a power strip will mimic this I dunno and as I mentioned I'm too lazy these days to set up a bench experiment and spend several days running tests - hell, at this point about 1/2 of my test equipment needs overhauled and calibrated and I'm looking for a younger tech to pass some of it on to!

Beware, if you don't know, that MB amps are some of the hardest to replace parts on and generally poorly engineered while nicely designed. OK until they break but some of my greatest repair headaches were how to disassemble a MB and make a test repair without elaborate jigs and adapters and such. Did warranty for them for a while and the reimbursement really wasn't worth the price (but a good service shop repair all their customer stuff whatever).

Boogie on,

Rob

[Russell Vance]

Hi again Rob, Thought the mention of Germanium would do it! My first fuzz box back in the early seventies was as noisy as a train wreck but very unique.....dry sounding is not a term I would use.

We use a lot of Mesa amps (mainly the bigger heads) and pretty much have seen it all with Mesa - however, I must say that their efforts in the last few years to address the general reliability (and some specifics I think) has been very worthwhile for them. The recent, latest generations of their amps has seen reliability return to the brand. I have no affiliation or endorsement with MB but I also hang out with the Mesa National distributors long suffering Amp technician who is of the same view....a lot better in every way.

And, for Rick, nice work -we use the Voodoo Labs power supply for most of our board builds and I can recommend it to anybody. Another good thing about it is it comes with a proper power cord and internal power so there is no stupid "wall wart" power pack with a skinny power lead to get beaten up on stage. I stick a perspex cover with an extended dropped lip over the top of the unit with some velcro tabs to protect the connectors and cooling vents from beer and water spills and that's about it. Nice unit.

Rusty.
Rusty.