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  • HP2621A nonvol backup battery

    From vjp2.at@at.BioStrategist.dot.dot.co@21:1/5 to All on Fri Feb 24 14:52:31 2023
    Looking to identify the 4v battery used to backup settings on 1980 HP2621A CRT video display terminal. I can't find the battery type online. Seems all the manuals are truncated at chapter 5. It is discontinued and I just want
    the specs. seems 4.2v Hg or 3.8v Li.


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  • From steve1001908@outlook.com@21:1/5 to vjp2.at@at.BioStrategist.dot.dot.co on Fri Feb 24 15:15:39 2023
    On Fri, 24 Feb 2023 14:52:31 -0000 (UTC),
    vjp2.at@at.BioStrategist.dot.dot.com wrote:

    Looking to identify the 4v battery used to backup settings on 1980 HP2621A
    CRT video display terminal. I can't find the battery type online. Seems all >the manuals are truncated at chapter 5. It is discontinued and I just want >the specs. seems 4.2v Hg or 3.8v Li.

    Hg is bad for marketing. It was probably discontinued when everybody
    found out that mercury (Hg) was a dangerous poison.

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  • From vjp2.at@at.BioStrategist.dot.dot.co@21:1/5 to All on Fri Feb 24 17:22:28 2023
    Ok, say I need a rechargeable 4v battery.
    What Amps likely? Any added circuitry?
    On the terminal.


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  • From ehsjr@21:1/5 to vjp2.at@at.BioStrategist.dot.dot.co on Fri Feb 24 18:31:45 2023
    On 2/24/2023 9:52 AM, vjp2.at@at.BioStrategist.dot.dot.com wrote:
    Looking to identify the 4v battery used to backup settings on 1980 HP2621A
    CRT video display terminal. I can't find the battery type online. Seems all the manuals are truncated at chapter 5. It is discontinued and I just want the specs. seems 4.2v Hg or 3.8v Li.



    Here's a _general_ answer.

    A setting holding backup battery does not need to supply
    a lot of current. I don't know what your device needs,
    but it is likely very low, perhaps not measureable with a
    dmm as it may draw current in pulses.

    That said, there are plenty of lithium batteries you
    can choose from, and small voltage boost converters
    (look on ebay) you could use to boost to 4.2 volts.

    You may not need exactly 4.2 volts - I have no idea
    what your device needs, other than what you posted,
    except that setting backup is almost always (always ?)
    very low current.

    Ok, assuming 4.2 volts, here's where we are, so far:
    lithium===>boost circuit===>device

    Now, you want to charge the battery. Ebay has lithium
    cell charger/protector circuits. Now your circuit looks
    like this: (view in fixed font)
    lithium=+=>boost circuit===>device
    |
    chg/pr==+

    In case the view is "scrambled" you'll connect the
    charge/protect (chg/pr in the diagram) to the same
    battery terminals that the boost circuit connects
    to.

    Ok, that's the general idea - using lithium, lithium
    charge/protection circuit and boost (or buck/boost)
    converter. You need to know what you're doing with
    lithium batteries, how to protect them etc, and how
    to properly connect to your 2621A.

    Good luck.
    Ed

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  • From vjp2.at@at.BioStrategist.dot.dot.co@21:1/5 to All on Tue Feb 28 19:59:50 2023
    Thanks. I have found there are 3.7v batteries that look like the original out there and they even come with chargers.


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    Vasos Panagiotopoulos panix.com/~vjp2/vasos.htm
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  • From whit3rd@21:1/5 to vjp...@at.biostrategist.dot.dot.com on Thu Mar 9 00:08:46 2023
    On Tuesday, February 28, 2023 at 11:59:54 AM UTC-8, vjp...@at.biostrategist.dot.dot.com wrote:
    Thanks. I have found there are 3.7v batteries that look like the original out
    there and they even come with chargers.

    I doubt you want those. The primary-cell lithium batteries (3.6V fresh, 3.0V at end-of-life)
    are what would have been in a 1980 device, not lithium ion rechargeable batteries.
    A few lithium vanadium pentoxide cells were available, but rare. If the 2621A doesn't charge the battery, you want a nonrechargeable Li battery.
    If it DOES charge it, you probably want a NiCd stack of button cells...

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  • From Charles Lucas@21:1/5 to All on Thu Mar 9 09:32:08 2023
    On Thursday, March 9, 2023 at 2:08:49 AM UTC-6, whit3rd wrote:
    On Tuesday, February 28, 2023 at 11:59:54 AM UTC-8, vjp...@at.biostrategist.dot.dot.com wrote:
    Thanks. I have found there are 3.7v batteries that look like the original out
    there and they even come with chargers.
    I doubt you want those. The primary-cell lithium batteries (3.6V fresh, 3.0V at end-of-life)
    are what would have been in a 1980 device, not lithium ion rechargeable batteries.
    A few lithium vanadium pentoxide cells were available, but rare. If the 2621A doesn't charge the battery, you want a nonrechargeable Li battery.
    If it DOES charge it, you probably want a NiCd stack of button cells...

    I have been following this thread for several weeks now. I found it interesting.

    Just a quick thought, If the terminals fit to the length of the battery I speculate
    might work, provided the physical width of the battery chamber (which holds
    the battery in place can support), assuming the numeric values (for voltage, etc...
    indicated remain constant), one could use an "N" type battery in some situations.
    Nickle Cadmiums (Ni-Cad's) are very expensive these days- retail cost is over 5 bucks
    for one or two of the Ni-Cad's (in current 2023 prices, due to recent world events,
    high inflation, etc.. ). One 'N' type battery or similar type may very well work (as
    long as it is rated properly and fulfills all of the other previously indicated criteria)
    and may help you to get the task accomplished at a far less expensive financial outlay. With the rise in prices these days, I am surprised more people "seem like
    they have to take out a second mortgage", just to actually buy the stuff. Big thing
    is safety, meeting all of the ratings and requirements, but price is really important
    to. Just thought I would mention that.

    Good Luck. Hope this helps out.

    Charles Lucas
    Senior Electronics Technician
    Senior Technical Consultant

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