Newsflash ! good batteries gone bad, news @ 11

[dacflyer]

anyone have an explaination for me ??
i had 3 good working rechargable batteries for my SONY camera, i took it with me on vacation, well since it had passed thru x-ray at the airport, and i got to my destination, i discovered in a unfortunate time that all the batteries were dead.. 1 barely will recharge, its the newest one, the 2nd and 3rd will not even take a charge now..has something in my travels killed my batteries? or is it some weird fluke that they all went suddenly bad ??

[MrAl]

Hi dac,

It's unfortunate that these days you dont know what the heck you
are getting when you buy something. It's no different with cells
like these, i would bet NiMH.

Some cells go dead or just dont work right for no apparent reason.
For example, a while back i bought an Energizer 15 minute charger
and later bought 4 NiMH cells rated 2500mAh. Within a couple weeks
(maybe not even that long) the things would charge, but then would
discharge in only two days even with no use at all ! I called Energizer
and got a coupon for 10 dollars to get new cells, and i bought a different
kind instead of the 2500mAh cells because i was not the only person
to have this problem...apparently many many people have had this
problem and wrote about it somewhere on the web. The buzz now is
stay away from Energizer 2500mAh cells, and go with almost anything
else, but the Eneloops (Sony) are the best because they have a very
slow self discharge.

There is one thing you can try, and that is to recondition the cells.
To do this you discharge them, then charge them back up, then
discharge again, about 10 times or so. This is supposed to bring
them back to life if they grew dendrite crystals in them, but i've
never tried this myself. Other companies now make low self
discharge (LSD) cells too now, like Rayovac, and Kodac, or they
may be the same thing just packaged differently. I have some
Kodacs, and i did tests (6 months for one test) and found them
to behave the way they are advertised to behave, which is very
low self discharge over long periods of time like a year.
You could probably find a ton of info on these by doing a search.

BTW, if you think it's the charger rather than the cells then do
a quick test with a wall transformer, a diode, and a current limiting
resistor. Connect the cells in series, connect the diode and resistor
in series and connect to a dc wall wart (maybe 9vdc) and charge
at 100ma for 24 hours. If the cells work after that it could be
the charger that is bad.

I've zapped NiCd's back into operation in the past, but i find that
after they grow crystals they start to discharge faster as they
lose capacity once that happens. Zapping gets them back but
they never work quite the same after crystal growth.
Perhaps reconditioning them would have helped.

Good luck, and let us know what you do next.

[dacflyer]

well, the charger is good, i know, the batteries when i left home were full charged, but when i got to my destination in europe, i wanted to make some fotos and all 3 batteries were dead as a doornail.
1 will recharge, but the other 2 won't when i put them in the charger the charge light comes on for a sec, then goes out, the one pack that will charge, charges to about 80%
these batteries are custom to the camera the SONY MAVICA series
i like my camera with its 14X optical zoom, even tho its the one that uses floppy disk,
so theres really no way to condition the batteries, i took an old one apart long time ago, the battery is built like a laptop battery, with internal onboard controller, and the charger is a switcher type, universal voltage. 120 - 220 volt.
so i think when i get back home, i'll just order me 2 new ones
i wonder if high altitude had anything to do with the batteries going sour.
i had them as carry on, so they weren't in the belly of the plane. i have no idea if the luggage area is temp controled or not,, but i had mine in cabin with me.
maybe it was just bad luck

[CeaSaR]

DAC,

Do you remember if there is anything on the controller that might be
affected by x-rays / ESD from outside sources? Could be that something
opened or shorted inside, during the trip through the airport scanner,
causing the discharge / lack of ability to charge. Of course, you should
check that out after you get a new battery.

CeaSaR

[Bigglez]

anyone have an explaination(sic) for me ??

Three dead batteries and only one charger?
I would suspect the charger is at fault.

Apart from using the batteries in either the charger
or the camera have you tried to measure the
battery voltage with a DMM?

Have you tried to discharge the batteries with a
load resistor to make sure they are fully discharged
and then put them on the charger?

Do you have a second charger to substitute for the
first one?

[MicroRem]

Hi Dac, I am a rep for a major manufacturer of X-ray machines such as those at airports. Typical dose per pass of x-ray for carry-on baggage is between .1 and .3 m/Rem per pass. At this dose, not even 1600 asa/iso film is effected. Your battery problem was not a result of x-ray exposure.

best regards

Tom

[dacflyer]

ceasar >> sorry, i am not sure whats all on the onboard controller in the battery packs, i just know its all surface mount ..

bigglez >> i did have access to a meter, the charger is working ok, the one pack is still holding out ok, but might need cycled.
the others are only about a few volts, i just guess it was such luck for them to go. i have nothng else here to test with, so it will have to wait til i get home.

microrem >> thanks for the info, i wasn't sure.. just my luck...lol

[haklesup]

I agree wih MicroRem that the X-rays would not have caused premature failure of the batteries or the charger. Much stronger x-ray systems are routinely used in semiconductor and microelectronic failure analysis and is generally considered non-destructive. I just signed on to rep a really cool X-Ray CT system for semiconductor F/A and metal casting applications. It can do a virtual cross section of a BGA solder joint inside the package at several thousand times magnification. These systems generate x-rays from 50kV to 160kV sources, and that's significantly hotter than an airport system.

I might suggest that all three batteries may have been purchased about the same time, have similar capacity and saw nearly identical service in rotation making them fail nearly the same time and same way. I might also speculate that on your vacation you left the batteries in a hot car, in beach bag or otrherwise subjected them to very hot conditions for at least a few hours which is a known battery killer for most technologies.

I vote for enviornmental conditions coupled with age. However, a defective charger is also reasonably likely especially if you only have one. Have you metered the charger output (V and I) without load and with a passive 10ohm or 50 ohm load to simulate a charging battery. Collapse of charger voltage under load wouldn't be good in most cases. No load voltage dosen't say much.

[MicroRem]

We typically run the tube at 140 kv, with current of about 0.5 ma. I would guess for in a ndt application you run more tube current. We collimate the beam down to about a millimeters width and the object is scanned as it passes through the beam on the conveyor belt.

sorry for hijacking the thread


Tom

[dacflyer]

hakklesap >> the batterys were all bought at different times, and none were in any extreme enviroment.. no beach or hot car..nothing here is warm in germany right now...high winds and cold rain...Phuuu i came at a bad time..lol
oh well, no matter i am glad to be visiting family here..


since were on the subject, whats the gyro spinning motor sound for in hospital x-rays.. whats the purpose of it ?

[haklesup]

And since you carried on your batteries, they saw normal temps in the cabin with you as well. Time for a closer look at the charger or maybe the device you use it in is killing them somehow perhaps by exceeding max current capacity and killing them too far (speculation again)

I'm no expert on X-Ray systems yet, we are just announcing our distributorship at our upcoming trade show in november. I'm still just the curve tracer guy at work (thats what I design, manufacture and sell for nearly 20 years)

However I recently have suffered through almost a dozen X-Ray sessions at the hospital in the last 2 months so I am familiar with the sound you speak of. Mostly I am commenting on the big system in the radiology dept suites, not so much the bedside portables, I only had one of those and don't quite remember.

I actually hear two sounds. One I think was just a high speed fan used to cool the tube in the head unit, it runs for 4-5 seconds. I am not sure what the other overlapping buzz is, the one that lasts 1 second in the middle. It is either a sound from the high voltage circuit or IMO more likely, just intentional audible feedback so the patient knows when the snapshot occurs and can start breething again. I am generally instructed to start breathing again after that buzz and before the longer one ends. There is no reason the HV circuit would Have to make any noise.

A friends brother is an X-Ray tech at a hospital, I'll ask and maybe get back to that later. It will take a few days though.

[Bigglez]

since were on the subject, whats the gyro spinning motor sound for in hospital x-rays.. whats the purpose of it ?

A high power X-Ray tube uses a rotating anode to
distribute the heat from the beam.

Prior to exposure the anode motor is turned on and
spins up very fast. Once at speed the X-Ray exposure
can commence. Even brief (less than ten second)
exposures will melt a stationary anode at these power
levels.

Upon completion of the exposure the motor is turned
off to conserve the bearing life. The rotor has a high
pitched whine when spinning.

In a dental X-Ray you can usually hear both the rotating
anode and the unfiltered 60Hz hum when the HV kicks in.
Smaller dental X-Ray sources are fixed anode, so no
rotation noise.

[dacflyer]

do you mean that the anode rotates inside the tube ?? or ???

[Bigglez]

do you mean that the anode rotates inside the tube ?? or ???

Yes! I edited my last post - TMI! But as you've asked

A high power X-Ray tube uses a rotating anode to
distribute the heat from the beam.

The anode is held in bearings and attached to a copper
cup that forms the rotor of an induction motor.

The anode and cup (and bearings) are inside the glass
envelope and under vaccum. The rotor is driven by
a rotating magnetic field from a stotor coil outside the
glass envelope.

Prior to exposure the anode motor is turned on and
when up to speed the exposure can commence. Even
brief (less than ten second) exposures will melt a
stationary anode at these techniques.

A dental X-Ray machine runs from 120V single phase
AC, and has a capacitor-run for the anode motor.
Bigger tubes use two phases of the three-phase supply
to drive the anode motor stator. It's about one horse
power to get the anode moving quickly.

In dental X-Ray you can usually hear both the rotating
anode and the unfiltered 60Hz when the HV kicks in.
Smaller dental X-Ray sources are fixed anode, no
rotation noise.

Modern HV tanks are probably high frequency, but
may chop the DC at 30Hz to save on PSU costs.

Upon completion of the exposure the motor is turned
off to conserve the bearing life.

I have one or two bad "tube inserts" (the glass tube
part) in my collection and these had either
spiral tracks or puddles of previously molten metal.
The anode is typically made of molybdenum alloy.
Some have graphite backing to hold more heat
calories (longer exposures, such as CAT scanning
and NDT).

A typical CAT scanner "technique" is 150kV at
100mA or 15kW of DC input power to the tube.
Only one percent of DC power emerges as X-Ray
energy, so the tube housing has to remove a lot of
heat. Most use oil (electrical insulator and heatsink).
CAT scanners have an oil reservoir and pump.

Next time you get an X-Ray ask the tech what
"technique" was used. Gets the conversation going!
They will give you milliamps (X-Ray beam volume)
and kilovolts (X-Ray beam hardness).

Next week we'll review "Digital X-Ray Film"...

[dacflyer]

cool thanks,,, my dentist uses a electronic thingie now attached to the computer,,its like a digital x-ray reciever makes instant pics. pretty cool i think,,still uses the x-ray gun tho...the part in my mouth is kinda bulky tho.. but its ok... ok,ttyl