Re: rechargeable batteries, was Re: Wireless

["IronMan Mike Curtis" <ironman@xxxxxxxxxxxxxxxxx>]

From: "G." <gigs@xxxxxxxxxxxxxxx>

> I bought a set of NiMH rechargables for my Harp Commander and effects
pedals
> after I realised that they pay for themselves after three uses or so.
>
> The NiMH packet says they don't develop "memory" unlike the NiCd
batteries.  I
> haven't used mine long enough to have an opinion on this.  But because of
this I
> recharge the batteries fully before using them so that they don't go flat.
At
> the moment they've got around 6+ hours of continual life in them which
makes it
> pretty safe to use them in this way.
>
> What is your experience with them?

Here's some links to info on NiMH batteries.

http://www.digibattery.co.uk/ni-mh_store1.html
http://www.dansdata.com/gz011.htm

NiCds have a "memory effect".  The metal in NiCds is sintered to present a
larger surface to electrolytes and generate higher current.  If they're only
partially discharged regularly, a barrier is built up, and the useful life
is limited by that barrier.

I've been using NiMH's for several years, and NiCds a lot longer than this.
The NiMH's don't seem to need cycling.  At least I haven't noticed it yet
(and if these were anything like NiCds in this respect, I would have).  The
NiCds are quite bad in this regard.  You need to periodically discharge them
to where the LED on the wireless comes on (they drop below 7.0 volts), but
not *completely* (i.e. you can't just leave it on overnight).  If they
discharge completely, there's a very real chance that one cell will reverse
charge.  When this happens, the battery is pretty much ruined.  I've read
stuff about "zapping" them back to life by force-charging them with an
overvoltage, but in my experience, this doesn't work.

There are quick chargers for these types of batteries, but in my experience
the best chargers are "nomal" rate, i.e. 1/10th the batterys amp hour
capacity (most of the heavy duty ones are 150 mAH, so a 15 milliamp charger)
for 14 hours.  The faster chargers heat up the batteries and eventually
cause them to vent, drying them out.

NiMHs can be had in the USA for around $5 (i.e. at Walmart), about 2.5 times
the going rate for brand name alkalines, so yes I too save some serious
money using them.  My favorites are RayOVac, which are 8.4 volts @ 150 mAH.

I actually have a "charging station" here, consisting of a bank of chargers
plugged into an outlet strip.  I carry a total of six batteries now, 2 in
the Nady transmitters (I have a Wireless One and Wireless 3D), and four
spares in a couple of Lee Oskar harp boxes.  I also keep a package of
alkalines, just in case.  I rarely need these, but it's happened a couple of
times.

For a four hour night, I'll usually kill one battery, the one on my harp
(for some reason, that transmitter draws more juice).  When this happens, I
change both batteries.  At absolute worst (if it dies at the beginning of a
harp instrumental), it's a minor inconvenience.  Most often, it's just time
for a bass pedal solo as I change batteries.  But this is live music, and
all kinds of things happen on a regular basis - a string breaks, a cable
gets unplugged, a volume control gets noisy, you suck out a reed, etc.
Rather than viewing it as a negative, I just think of it as something to
make our live performances that much more interesting.

My buddy Walter Trout breaks strings at many gigs (he uses those little
skinny things).  When this happens, the organist takes over and soloes until
he can change the string.  I kind of view dying batteries in the same light.
Of course this has been happening to me for many years (I've always used a
lot of battery operated stuff, and had complicated and failure prone
setups), and I'm used to it.


- -IronMan Mike Curtis Band  http://www.ironmancurtis.com *Southland Blues
Magazine http://www.SouthlandBlues.com  Santa Monica 3rd St Promenade,
various times   Email my Cellphone for specifics (130 chr's max)
ironmanc@xxxxxxxxx
http://www.billhouse.com/songs/ironman/WalkingToNewOrleans.mp3