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Thread: Barrel Battery Replacement Options

  1. #11
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    I used to use the 3x or 4x AA or AAA packs, but I typically use a 1/2AA 3.6V cell in a holder nowadays. I've found the hermetically sealed Tadiran lithium thionyl chloride cells you can get in 1/2AA basically don't leak unless mechanically damaged or placed in really damp conditions where they can rust from the outside. The really long shelf life is nice, since the current draw is so low anyway.

  2. #12

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    Quote Originally Posted by glitch View Post
    I've found the hermetically sealed Tadiran lithium thionyl chloride cells you can get in 1/2AA basically don't leak unless mechanically damaged or placed in really damp conditions where they can rust from the outside. The really long shelf life is nice, since the current draw is so low anyway.
    I've still got an original Tadiran dated Oct., 1990 on my 486 test bed.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  3. #13
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    Quote Originally Posted by glitch View Post
    I used to use the 3x or 4x AA or AAA packs, but I typically use a 1/2AA 3.6V cell in a holder nowadays. I've found the hermetically sealed Tadiran lithium thionyl chloride cells you can get in 1/2AA basically don't leak unless mechanically damaged or placed in really damp conditions where they can rust from the outside. The really long shelf life is nice, since the current draw is so low anyway.
    My understanding is that the lifetime clock starts ticking the moment you put on a load on one, even if you return it to the shelf. I don't know if that's really true, however. I do know that the 3.6V 1/2 AA cells used in Power Macs will put in better than a decade, however. But I've had plain old alkalines in the same application run for 15 years.

  4. #14

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    Quote Originally Posted by Chuck(G) View Post
    My understanding is that the lifetime clock starts ticking the moment you put on a load on one, even if you return it to the shelf. I don't know if that's really true, however. I do know that the 3.6V 1/2 AA cells used in Power Macs will put in better than a decade, however. But I've had plain old alkalines in the same application run for 15 years.
    The one for the arduino requires something to be to be read or set to start it. I don't recall what it was, I'd need to look at the spec again.
    Dwight

  5. #15

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    While scanning ebay, I came across someone selling NiMH batteries to use in place of NiCad batteries. These are in the typical barrel package.
    Dwight

  6. #16

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    Quote Originally Posted by Dwight Elvey View Post
    While scanning ebay, I came across someone selling NiMH batteries to use in place of NiCad batteries. These are in the typical barrel package.
    NiMH batteries shouldn't be charged with a NiCad charger.

    A NiMH charger can charge NiCd; a NiCd charger would overcharge NiMH.

    NiMH cells cannot be charged with a NiCd charger as end of charge detection will not work.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  7. #17
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    NiMH barrel batteries have been around for a long time, so this is nothing new.

    At the very low charging/discharging rates used in motherboard RTC applications, it scarcely makes a difference between NiMH and NiCd. However, I suspect that the self-discharge rate of either is higher than the consumption by the RTC oscillator.

    So use a primary battery--it'll last just as long and may not even leak at the end of its life.

  8. #18

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    According to what I read, a 80ma NiMH can be trickled at .05C. The cells the fellow is selling, are 80maHr. Anything below 4 ma would be a trickle. Assuming the rail voltage is 5V, two 1n4148s in series with a 60 ohm resistor should be safe. The 60 ohm to protect the diodes and the diodes to keep a safe trickle at max charge. They probably won't get to maximum charge but that isn't important. 80% charge is fine, even 50%. If one cell is way out it is still basically a trickle.
    Dwight

  9. #19
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    Reading through the whole thread, nothing much new to say so just offer my thoughts. I probably wouldn't use the AA batteries since not only do you have to do the diode fix, the AA batteries (alkaline or not) can still leak. I'd probably opt for the coincell replacements instead. The one mentioned earlier with the built in diode sound like a great option, but I also know they make rechargeable coincells (no idea if the charging circuitry is compatible but since i've heard of folks doing this, i'd think it would be fine). The good thing about the coincells vs big ole batteries is that they shouldn't leak (even if they could, i'd imagine it wouldn't be enough to do any damage).

    The other things i've done in this situation is to either not bother replacing... I have a few machines i only use very rarely, so it's no small issue to just put the date in when you boot up. I have to with my 8 bit machines anyway. The other thing I've done but i'm not necessarily advocating, is in my Amiga 3000 I replaced the battery with a cordless phone battery. It can still eventually leak, so the only advantage to this is that you can run it somewhere away from the board where it won't damage anything if that happens, and of course that the charging circuitry can stay in place.
    -- Brian

    Systems: Amstad PCW 8256, Apple IIe/II+/Mac+/Mac 512k, Atari 800/520STFM, Commodore 64/Amiga 3000/PET 4032/SX-64, IBM PS/1 2121-B82, Kaypro II, Osborne 1, Tandy 1000 SX, TI-99/4A, TRS-80 Model 4 GA

  10. #20

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    Quote Originally Posted by ngtwolf View Post
    Reading through the whole thread, nothing much new to say so just offer my thoughts. I probably wouldn't use the AA batteries since not only do you have to do the diode fix, the AA batteries (alkaline or not) can still leak. I'd probably opt for the coincell replacements instead. The one mentioned earlier with the built in diode sound like a great option, but I also know they make rechargeable coincells (no idea if the charging circuitry is compatible but since i've heard of folks doing this, i'd think it would be fine). The good thing about the coincells vs big ole batteries is that they shouldn't leak (even if they could, i'd imagine it wouldn't be enough to do any damage).

    The other things i've done in this situation is to either not bother replacing... I have a few machines i only use very rarely, so it's no small issue to just put the date in when you boot up. I have to with my 8 bit machines anyway. The other thing I've done but i'm not necessarily advocating, is in my Amiga 3000 I replaced the battery with a cordless phone battery. It can still eventually leak, so the only advantage to this is that you can run it somewhere away from the board where it won't damage anything if that happens, and of course that the charging circuitry can stay in place.
    Regular lithium coin cell do eventually leak but don't cause as much damage as the alkaline cells do. I know this because one leaked after 17 years in my Suburban's key fob. I thought is was ruined. Water wouldn't touch the electrolyte. It was an oil based stuff. I eventually found that BrakeKlean worked and cleaned it off the circuit board. I had to flush the plastic fob body quickly as it was dissolving the plastic as well. Other solvents may have worked and been less trouble for the fob body but that was what I used.
    Dwight

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