1. This forum section is a read-only archive which contains old newsgroup posts. If you wish to post a query, please do so in one of our main forum sections (here). This way you will get a faster, better response from the members on Motherboard Point.

UPS waveform question for SUN servers

Discussion in 'Sun Hardware' started by JJ, Dec 16, 2008.

  1. JJ

    JJ Guest

    I've been somewhat ignorant about UPSs. It was just recently that I
    discovered that the main difference between the two UPSs we have is
    that one produces a true sine wave (APC smart-UPS), while the other
    (which was cheaper but with a higher VA rating) produces a stepped
    approximation (APC smart-UPS SC).

    These UPSs sit between the wall outlet and two aging sun blade
    workstations (a blade 1k - over 5 yrs old, and a blade 2k about 4 yrs
    old).

    The more expensive UPS with the true sine-wave output just had its
    battery die. During its life, this UPS has caused more trouble than
    it has alleviated - with the battery sometimes discharging for no
    apparent reason and the computer being unceremoniously shut off - why
    in this eventuality the UPS would not just run the computers directly
    off the incoming power is beyond me, but as I said, I'm pretty
    ignorant about these things. I even had the UPS unit and the battery
    replaced, but I've seen this type of anomaly occur about once a year.
    I thought a UPS was supposed to prevent unwanted shutdowns!
    Afterwards, the UPS battery would recharge and all would seem fine
    again.

    Anyway, because the battery is now truly dead (or so says the UPS
    unit), I decided that now would be a good time to upgrade the unit to
    one that is more dependable and with a higher VA rating. So I figured
    I would get another of the SC units - haven't had any trouble with
    that one since I got it about a year ago. Which is when I learned
    about the sine-wave Vs. stepped approximation thing. Maybe the SC
    unit has just never really been needed since I got it and has always
    just passed the power directly through from the wall. At least it
    hasn't shut off my system without warning.

    My real question is, do these computers (Blade 1k and Blade 2k) really
    need a true sine wave of current from the UPS, or is a stepped
    approximation good enough (especially for the short periods of time
    they would be running off of the UPS)? Would these machines just shut
    down if they started seeing a stepped waveform? Would the stepped
    waveform cause damage to any of the components if the power was out
    for a long enough time? Would I be better off with no UPS for these
    computers than ones with a stepped waveform?

    Thanks for any info regarding this.

    -J
     
    1. Advertising

  2. JJ <> wrote:
    >
    > I've been somewhat ignorant about UPSs. It was just recently that I
    > discovered that the main difference between the two UPSs we have is
    > that one produces a true sine wave (APC smart-UPS), while the other
    > (which was cheaper but with a higher VA rating) produces a stepped
    > approximation (APC smart-UPS SC).
    >
    > These UPSs sit between the wall outlet and two aging sun blade
    > workstations (a blade 1k - over 5 yrs old, and a blade 2k about 4 yrs
    > old).
    >
    > The more expensive UPS with the true sine-wave output just had its
    > battery die. During its life, this UPS has caused more trouble than
    > it has alleviated - with the battery sometimes discharging for no
    > apparent reason and the computer being unceremoniously shut off - why
    > in this eventuality the UPS would not just run the computers directly
    > off the incoming power is beyond me, but as I said, I'm pretty
    > ignorant about these things. I even had the UPS unit and the battery
    > replaced, but I've seen this type of anomaly occur about once a year.
    > I thought a UPS was supposed to prevent unwanted shutdowns!
    > Afterwards, the UPS battery would recharge and all would seem fine
    > again.
    >
    > Anyway, because the battery is now truly dead (or so says the UPS
    > unit), I decided that now would be a good time to upgrade the unit to
    > one that is more dependable and with a higher VA rating. So I figured
    > I would get another of the SC units - haven't had any trouble with
    > that one since I got it about a year ago. Which is when I learned
    > about the sine-wave Vs. stepped approximation thing. Maybe the SC
    > unit has just never really been needed since I got it and has always
    > just passed the power directly through from the wall. At least it
    > hasn't shut off my system without warning.
    >
    > My real question is, do these computers (Blade 1k and Blade 2k) really
    > need a true sine wave of current from the UPS, or is a stepped
    > approximation good enough (especially for the short periods of time
    > they would be running off of the UPS)? Would these machines just shut


    I haven't check the spec sheets on these products, but since they may be
    OK.

    The real issue is good vs. bad UPSes. Square wave UPSes are cheaper to
    make and will be inherently closer to bottom of the barrel than one that
    produces the correct sine wave.
     
    1. Advertising

  3. DoN. Nichols

    DoN. Nichols Guest

    On 2008-12-16, JJ <> wrote:
    >
    > I've been somewhat ignorant about UPSs. It was just recently that I
    > discovered that the main difference between the two UPSs we have is
    > that one produces a true sine wave (APC smart-UPS), while the other
    > (which was cheaper but with a higher VA rating) produces a stepped
    > approximation (APC smart-UPS SC).


    O.K. The pure sine wave is better for systems with input
    transformers (typically linear regulated supplies), which are more
    likely to be found in audio equipment these days than in computers.

    > These UPSs sit between the wall outlet and two aging sun blade
    > workstations (a blade 1k - over 5 yrs old, and a blade 2k about 4 yrs
    > old).


    The SB-1K and SB-2K use the same power supply. I've got a spare
    (from a damaged chassis which I got from eBay -- but what I needed was
    fine, so the damage did not matter to me. :)

    I not too long ago happened to take the power supply apart
    (looking for a C-ring from one of the CPU modules which had gone into
    hiding because someone had apparently tried unscrewing one jackscrew
    completely before going to the other. :-(

    The interior of the power supply is purely a work of art. And
    It is a switching power supply with auto input voltage switching. I
    doubt that it even knows that the waveform is only a stepped
    approximation.

    > The more expensive UPS with the true sine-wave output just had its
    > battery die. During its life, this UPS has caused more trouble than
    > it has alleviated - with the battery sometimes discharging for no
    > apparent reason and the computer being unceremoniously shut off - why
    > in this eventuality the UPS would not just run the computers directly
    > off the incoming power is beyond me, but as I said, I'm pretty
    > ignorant about these things. I even had the UPS unit and the battery
    > replaced, but I've seen this type of anomaly occur about once a year.


    Hmm ... circuit breaker tripped because too much load was on all
    of the outlets serviced by that breaker?

    Cat or dog knocked the plug from the wall? (This happened to my
    wife's computer recently. I was hearing the alarm, but we have so
    many things running that I could not track it down (I thought that it was
    the keyboard beep). It communicated via the serial port to her SB-1K
    and shut it down cleanly as intended, instead of suddenly dropping the
    power from under the machine. If she had looked at the LEDs on the USP
    front panel, she would have seen that it was running from battery power
    and we could have prevented the shutdown entirely.

    Automatic battery test with the VA load too close to the maximum
    rating of the UPS and aging batteries? I've encountered this causing
    the UPS to shut down for a short time when it shifts to powering the
    system from the batteries to see how they handle the load. Normally,
    all you may notice is a beep from the UPS when it switches to battery
    power, and then silence. It typically gives beeps in Morse Code to tell
    you what it is alarmed about. :)

    > I thought a UPS was supposed to prevent unwanted shutdowns!


    Not if it loses AC power long enough.

    You need to have the audible alarm turned on, and to notice it.
    (I failed the latter in that one case. :)

    > Afterwards, the UPS battery would recharge and all would seem fine
    > again.


    It sounds like the power cord connector loose in the outlet. Or
    perhaps a house made during the period when aluminum house wiring was
    legal. The aluminum crushes under the screws over time and starts to
    make poor contact, which could leave your UPS without power for long
    enough to discharge the batteries and to force a shutdown.

    > Anyway, because the battery is now truly dead (or so says the UPS
    > unit), I decided that now would be a good time to upgrade the unit to
    > one that is more dependable and with a higher VA rating. So I figured
    > I would get another of the SC units - haven't had any trouble with
    > that one since I got it about a year ago. Which is when I learned
    > about the sine-wave Vs. stepped approximation thing. Maybe the SC
    > unit has just never really been needed since I got it and has always
    > just passed the power directly through from the wall. At least it
    > hasn't shut off my system without warning.


    I don't think that the SB-1K or SB-2k care whether it is true
    sine wave, stepped approximation, or even just a square wave. :-

    > My real question is, do these computers (Blade 1k and Blade 2k) really
    > need a true sine wave of current from the UPS, or is a stepped
    > approximation good enough (especially for the short periods of time
    > they would be running off of the UPS)?


    They should not care.

    > Would these machines just shut
    > down if they started seeing a stepped waveform?


    Nope!

    > Would the stepped
    > waveform cause damage to any of the components if the power was out
    > for a long enough time?


    Nope -- except perhaps for transformer-powered audio equipment.

    > Would I be better off with no UPS for these
    > computers than ones with a stepped waveform?


    Nope!

    My own preference is an UPS no longer made -- but available on
    eBay (usually quite a few). Look for "Best power systems" and
    "FERRUPS". These have a Sola type of constant voltage transformer, so
    low power is just boosted to the proper voltage with no need for the UPS
    to actually run from the battery, and surges are automatically reduced
    to reasonable values. When the power actually goes away, the UPS starts
    driving other windings on the transformer from the battery, and
    continues to produce a clean sine wave.

    There is a serial port on the UPS which an be connected to ttya
    or ttyb and monitored by a dameon called "checkups" which can be
    downloaded from the people who took over Best Power Systems if you don't
    get the CD-ROM which includes it as part of the package.

    It comes pre-compiled for several versions of unix, including
    Solaris (and even SunOs 4.x.x IIRC), and with source code to allow you
    to compile it for other systems.

    You start it from an entry in /etc/init.d linked to one in
    /etc/rc2.d (or wherever you want it to start). You can pass to it how
    long before the UPS runs out of battery charge you want the system to
    start shutdown, and how long you want to give the system to shut down
    before you actually drop the power to preserve the batteries.
    (Discharging them fully does terrible things to their life.) The UPS
    shuts off the power when it is told to, and then returns power once AC
    power returns. The system can be set up to boot on power restoration.

    I've got a 700 VA BEST UPS powering my wife's SB-1K, a 1.4 KVA
    one powering my SB-2K with a tray of seven 72 GB FC drives in a zfs
    system, and a 2KV one with four 12V batteries in series powering the
    server (Sun Fire 280R and two trays of seven 72 GB FC drives in zfs
    filesystems, plus an Exabyte 430 tape library, and two Sun Ultra 10s,
    two SPARCstaton 5s, a Sun Ultra 5 (acting as a firewall), a
    router/T1-(CSU/DSU), several twisted-pair ethernet hubs, and
    occasionally an Intel Mac Mini.

    If you get a BEST UPS -- ask them to ship it without the battery
    or batteries, and get a new one to fit it once it is at your home. The
    UPS itself is quite heavy, and add a gel lead-acid battery and you will
    have something too heavy to move. I did bring the 2KVA one up through a
    trapdoor from the garage/workshop with a hoist and winch. The others
    were carried upstairs as the main chassis, the case, and the battery,
    and all were joined only when in the final location. (You will likely
    need some wrenches to attach the cables to the batteries, and be careful
    to not short across the two terminals with the tools. :) Typically, I
    needed a 1/4" drive ratchet set with sockets for 1/4-20 bolts and nuts
    on the larger ones, and a 3/16" Allen wrench for the smaller one for the
    700 VA unit. I got that battery (34 AH) at a hamfest (A vendor cycling
    his stock which had been kept properly charged to sell newer stock to
    his regular customers), and Batteries Plus for the larger 80 AH ones for
    the 1.4 KVA unit and four of them for the 2.0 KVA unit.

    As long as the batteries are replaced every four years or so I
    expect no problems -- other than from my wife or the cats kicking the
    plug out of the outlet -- and then I expect a clean and graceful
    shutdown.

    Good Luck,
    DoN.

    --
    Email: <> | Voice (all times): (703) 938-4564
    (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
    --- Black Holes are where God is dividing by zero ---
     
  4. Guest

    On Dec 16, 2:06 pm, JJ <> wrote:
    > I've been somewhat ignorant about UPSs.  It was just recently that I
    > discovered that the main difference between the two UPSs we have is
    > that one produces a true sine wave (APC smart-UPS), while the other
    > (which was cheaper but with a higher VA rating) produces a stepped
    > approximation (APC smart-UPS SC).
    > ...
    > My real question is, do these computers (Blade 1k and Blade 2k) really
    > need a true sine wave of current from the UPS, or is a stepped
    > approximation good enough (especially for the short periods of time
    > they would be running off of the UPS)?  


    Output from a computer grade UPS (your cheapest ones) is also called
    stepped sine wave or modified sine wave. For example, the output from
    a 120 volt UPS in battery backup mode is two 200 volts square waves
    with a spike of up to 270 volts between those square waves. That
    output (even the spike) must not be destructive to any minimally
    acceptable computer. Industrry standards for computer power supplies
    make that apparent. So why spend maybe five or ten times more money
    for the 'so called' pure sine wave?

    When a UPS is installed for serious purposes, its battery typically
    lasts something less than 20 years. But plug-in UPSes are made as
    cheap as possible. Often its battery lasts only three years. A
    replacement battery may cost as much as an entire new UPS.

    A cheap UPS has only one function: to maintain power so that data is
    not lost. The typical cheap UPS can output power so 'dirty' as to be
    harmful to small electric motors and power strip protectors. But this
    power must never harm a computer. Also called a computer grade UPS.
     
  5. JJ

    JJ Guest

    Thanks for the detailed thoughts. It sounds like the stepped wave
    function should be safe for these computers.

    As for the failure of the old one, I guess the point is moot now, but
    none of your theories sound likely for the setup we have. All this
    stuff is sitting in a small but dedicated server room on a university
    campus that had all the electrical wiring updated about 5 years ago -
    I'm sure it well surpasses code for domestic wiring. No dogs or
    anything around to knock the plug out. Loads were all reasonable.
    Other computers and UPSs in the room suffered no problems during these
    anomalies.

    This one might be the closest culprit: "Automatic battery test with
    the VA load too close to the maximum rating of the UPS and aging
    batteries? I've encountered this causing the UPS to shut down for a
    short time when it shifts to powering the system from the batteries to
    see how they handle the load." Best I can tell is that the batteries
    discharged for some unknown reason - then the UPS tried one if its bi-
    weekly tests and *bang* - sorry not enough battery power for the 1/2-
    second (or however long it is) test.

    Whatever the problem - I've given up on that particular model and it
    looks like the one with the stepped approximation to a sine wave
    should be fine for these computers.

    Thanks.

    -J
     
  6. wrote:
    > On Dec 16, 2:06?pm, JJ <> wrote:
    >> I've been somewhat ignorant about UPSs. ?It was just recently that I
    >> discovered that the main difference between the two UPSs we have is
    >> that one produces a true sine wave (APC smart-UPS), while the other
    >> (which was cheaper but with a higher VA rating) produces a stepped
    >> approximation (APC smart-UPS SC).
    >> ...
    >> My real question is, do these computers (Blade 1k and Blade 2k) really
    >> need a true sine wave of current from the UPS, or is a stepped
    >> approximation good enough (especially for the short periods of time
    >> they would be running off of the UPS)? ?

    >
    > Output from a computer grade UPS (your cheapest ones) is also called
    > stepped sine wave or modified sine wave. For example, the output from
    > a 120 volt UPS in battery backup mode is two 200 volts square waves
    > with a spike of up to 270 volts between those square waves. That
    > output (even the spike) must not be destructive to any minimally
    > acceptable computer. Industrry standards for computer power supplies
    > make that apparent. So why spend maybe five or ten times more money
    > for the 'so called' pure sine wave?


    The reason to spend more money is so the UPS actually works. It's not the
    sine wave you're after, it's that the UPS is designed and made to actually
    work correctly. Good output is a side effect of this.

    you'd be surprised at how many people drag garbage UPSes into datacenters
    with real power conditioning equipment and then cry when their UPS fails,
    even though it never saw a drop, brownout or surge.
     
  7. JJ

    JJ Guest

    This is a tangential question - and bear in mind that it was the
    "expensive" UPS that gave me all the troubles.

    Why would a UPS ever cause loss of power to the equipment connected to
    it (even if its battery dies), if the power coming from the wall is
    clean and steady? I mean, you're supposed to be able to pull the
    battery out and replace it with a fresh one without losing power to
    your hardware (as long as there is no power anomaly from the wall
    outlet during that process) - so why would a UPS that is not seeing a
    loss or fluctuation of power from the wall cut off power to the
    hardware? Surely if the thing is going to do a self test and cut off
    power from the wall for a bit, it should be smart enough to check
    before it does whether or not its battery is low (it knows that) or if
    the load is too high (which it also knows).

    -J

    > you'd be surprised at how many people drag garbage UPSes into datacenters
    > with real power conditioning equipment and then cry when their UPS fails,
    > even though it never saw a drop, brownout or surge.
     
  8. JJ <> wrote:
    > This is a tangential question - and bear in mind that it was the
    > "expensive" UPS that gave me all the troubles.
    >
    > Why would a UPS ever cause loss of power to the equipment connected to
    > it (even if its battery dies), if the power coming from the wall is


    That's a really good question.

    No real UPS should fail that way, but there's plenty of junk out there
    that does. Tiny UPSes lack bypasses, so when they fail, they just shut
    off.

    > clean and steady? I mean, you're supposed to be able to pull the
    > battery out and replace it with a fresh one without losing power to
    > your hardware (as long as there is no power anomaly from the wall


    It depends on the size. Some let you swap batteries, some can't be opened.
    Some have shitty connectors to the internal batteries, were some treat the
    batteries as a module with real (Anderson) connectors.

    > outlet during that process) - so why would a UPS that is not seeing a
    > loss or fluctuation of power from the wall cut off power to the
    > hardware? Surely if the thing is going to do a self test and cut off
    > power from the wall for a bit, it should be smart enough to check
    > before it does whether or not its battery is low (it knows that) or if
    > the load is too high (which it also knows).


    Most deskside UPSes are pretty stupid. If (more like when) the battery is
    weak/dead and it tries to switch to the inverter, it will just die and
    shut off. Maybe as you said, some unit try to test themselves and fail in
    the process.

    Giant UPSes are smarter. They have multiple bypasses where if they fail
    or are being serviced, they will continue to let line power though, even
    with the inverters dead.

    The logic is any power is better than no power.

    Also, proper maintenance is done in larger installations where somebody
    tests each battery yearly. If a battery is tested as weak, it gets
    replaced before it fails.

    You can't even get to the batteries is a small UPS, so there's no way to
    even test it without losing power if it's bad.
     
  9. * JJ:

    > My real question is, do these computers (Blade 1k and Blade 2k) really
    > need a true sine wave of current from the UPS, or is a stepped
    > approximation good enough (especially for the short periods of time
    > they would be running off of the UPS)?


    No. Computer PSUs are usually switched PSUs, and they don't care about
    if the output is true sinus or stepped sinus. Besides that, inverters
    (the components inside a UPS that convert DC to AC) always output a
    stepped sinus. The only difference is the resolution (number of steps).
    They never put out a true sinus.

    UPSes exist in three classes:

    - Standby UPS: simplest and cheapest variant, usually for low
    capacities. These UPSes just pass through mains power, and if mains
    power fails, they switch to battery power. The switching times (times
    between switch from mains to battery or vice versa in which power output
    is interrupted) are relative long, and they don't do power conditioning
    (filtering spikes and overvoltages in mains power to protect the
    connected equipment). I'd avoid them.

    - Line-Interactive UPS: more sophisticated than the Standby variant. The
    basic principle is the same but the Line Interactive variant has shorter
    switching times and offers power conditioning (filtering of surges,
    spikes and overvoltages, voltage levelling etc). They switch to battery
    power not only when mains fails but also when mains power is out of
    range. Line Interactive UPSes are usually used in capacities up to
    around 2.5kVA and are usually the best and most economic option
    (inverter which has energy "loss" is only used when run from battery)
    for equipment that falls into that load rating.

    - Online UPS: usually used for capacities from ~2kVA and above. An
    Online UPS operates its inverters constantly. In normal operation it's
    feeded by mains power that is transformed into a low voltage (usually
    the same voltage as the collective battery voltage) DC current, and when
    mains fails, the inverter gets fed from battery. These UPSes always
    output the same "quality" of power (offer the best power conditioning)
    but also they have the inverter constantly running which means they
    "consume" a fair amount of power for themselves, and since the inverter
    has a limited operating life it means higher service costs.

    > Would these machines just shut
    > down if they started seeing a stepped waveform?


    No, they don't care.

    > Would the stepped
    > waveform cause damage to any of the components if the power was out
    > for a long enough time?


    No.

    > Would I be better off with no UPS for these
    > computers than ones with a stepped waveform?


    No. There is no need to worry about the output waveform, but you should
    worry about the quality level of the UPS as such that you buy. As to UPS
    brands, my experience is that most APC UPSes are utterly crap and act up
    especially after the first batch of batteries has died.

    Better brands are Powerware/Best Power and (especially for capacities
    from 2kvA) also Sola/Hevy Duty.

    Benjamin
     
  10. Benjamin Gawert <> wrote:
    > * JJ:
    >
    >> My real question is, do these computers (Blade 1k and Blade 2k) really
    >> need a true sine wave of current from the UPS, or is a stepped
    >> approximation good enough (especially for the short periods of time
    >> they would be running off of the UPS)?

    >
    > No. Computer PSUs are usually switched PSUs, and they don't care about
    > if the output is true sinus or stepped sinus. Besides that, inverters
    > (the components inside a UPS that convert DC to AC) always output a
    > stepped sinus. The only difference is the resolution (number of steps).
    > They never put out a true sinus.
    >
    > UPSes exist in three classes:
    >
    > - Standby UPS: simplest and cheapest variant, usually for low
    > capacities. These UPSes just pass through mains power, and if mains
    > power fails, they switch to battery power. The switching times (times
    > between switch from mains to battery or vice versa in which power output
    > is interrupted) are relative long, and they don't do power conditioning
    > (filtering spikes and overvoltages in mains power to protect the
    > connected equipment). I'd avoid them.
    >
    > - Line-Interactive UPS: more sophisticated than the Standby variant. The
    > basic principle is the same but the Line Interactive variant has shorter
    > switching times and offers power conditioning (filtering of surges,
    > spikes and overvoltages, voltage levelling etc). They switch to battery
    > power not only when mains fails but also when mains power is out of
    > range. Line Interactive UPSes are usually used in capacities up to
    > around 2.5kVA and are usually the best and most economic option
    > (inverter which has energy "loss" is only used when run from battery)
    > for equipment that falls into that load rating.
    >
    > - Online UPS: usually used for capacities from ~2kVA and above. An
    > Online UPS operates its inverters constantly. In normal operation it's
    > feeded by mains power that is transformed into a low voltage (usually
    > the same voltage as the collective battery voltage) DC current, and when
    > mains fails, the inverter gets fed from battery. These UPSes always
    > output the same "quality" of power (offer the best power conditioning)
    > but also they have the inverter constantly running which means they
    > "consume" a fair amount of power for themselves, and since the inverter
    > has a limited operating life it means higher service costs.
    >
    >> Would these machines just shut
    >> down if they started seeing a stepped waveform?

    >
    > No, they don't care.
    >
    >> Would the stepped
    >> waveform cause damage to any of the components if the power was out
    >> for a long enough time?

    >
    > No.
    >
    >> Would I be better off with no UPS for these
    >> computers than ones with a stepped waveform?

    >
    > No. There is no need to worry about the output waveform, but you should
    > worry about the quality level of the UPS as such that you buy. As to UPS
    > brands, my experience is that most APC UPSes are utterly crap and act up
    > especially after the first batch of batteries has died.
    >
    > Better brands are Powerware/Best Power and (especially for capacities
    > from 2kvA) also Sola/Hevy Duty.


    I'd second the Eaton/Powerware units. They offer good driver support for
    weird systems, and are very efficient and small. The extenal rackmount
    batteries scale nicely as well, and can be replaced on a live system.
     
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Bob Martin

    Waveform storage & var. freq. playback

    Bob Martin, Nov 11, 2003, in forum: Embedded
    Replies:
    6
    Views:
    309
    Jim Granville
    Nov 12, 2003
  2. Brett Foster

    Waveform

    Brett Foster, Mar 4, 2005, in forum: Embedded
    Replies:
    5
    Views:
    539
    Brett Foster
    Mar 5, 2005
  3. Stephane

    waveform edition

    Stephane, Nov 4, 2005, in forum: Embedded
    Replies:
    5
    Views:
    571
    Anton Erasmus
    Nov 7, 2005
  4. John D Groenveld
    Replies:
    0
    Views:
    285
    John D Groenveld
    Oct 22, 2005
  5. EOL Batteries
    Replies:
    0
    Views:
    334
    EOL Batteries
    Mar 11, 2011
Loading...

Share This Page