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Thread: FTTP NTD box backup battery

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    Default FTTP NTD box backup battery

    Had the 'replace battery' alarm some time back so I dutifully charged out and got ripped off IMHO for a replacement 12V SLA battery which fixed the alarm problem (wasn't really a big deal). Did some tests on the old battery and it was absolutely fine with no degradation I could measure so I kept it charged up in tiptop condition until I got the 'replace battery' alarm again exactly 12 months after the last time it was replaced. Not coincidentally the first time I got that alarm it was exactly a year or 2 pretty much to the day from when the NBN was installed. So I shut down the NTD power supply and swapped back to the original battery (fully charged), fired the power supply up and all is good again.

    So I have to conclude that the 'replace battery' alarm is not based on battery condition but initiated arbitrarily by the ISP based on a simple timer. Seemed more than coincidental that the battery vendor had a rather large stack of these replacement batteries for a steady stream of eager customers at $45/battery, most of whom wouldn't check to see if the battery actually needed replacing as I did. Must be a lot of these batteries being thrown out unnecessarily not to mention the probability of some sharks making a living out of supplying and replacing batteries.

    Anyone here know more about this?



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    I have tested a few that have been showing as needing replacement.

    I have had the same result as you - battery is OK - even when under load. Reset it and it goes away.

    Definitely looks like a timed thing that causes it rather than an actual low battery

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    Mine has given the low battery alarm a couple of times. It always starts in the middle of the night, so I’ve permanently disabled the audible alarm.

    The first time, I just reset the alarm. A few weeks later, it did it again. The original battery was still under the two year NBN warranty, so bought a new one and got re-imbursed through my RSP.

    I re-purposed the original battery and it has been fine ever since. Maybe its internal resistance had started to go a bit high or something?

    The new battery threw a “bad battery” alarm a few months ago. I reset it and it has been fine since, so it must’ve just false triggered.

    I guess there must be thousands of perfectly good backup batteries in landfill because of this.

    The official source of batteries is here:

    I think I bought a Panasonic with the wide spade terminals from WES Components for about $30. I’d avoid the custy non-name ones from Jaycar and the battery supermaket places. They generally have the wrong terminals anyway.

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    That 2 year warranty on the original battery supplied by NBN lines up nicely with my first alarm which came up precisely to the day 2 years from initial start-up. That original install provided a phone line via the phone port on the NTD so the battery had a purpose then but I changed to a better plan at the end of that contract and now it's a VOIP phone on the current plan so the battery really isn't essential unless I were to install a UPS to power my router as well. The most recent alarm came up exactly 1 year after replacing the original and battery degradation is never that precise.

    I did some tests on the second battery (came from Battery World) and it's perfect too as far as I can tell. The box has been happy with the old original battery I put back in it 2 days ago so I'll wait to see if the alarm comes up again around 19th April next year.

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    I just went back through my records. I seem to be getting about 18 months between alarms.

    • NBN installed in late May 2016
    • Bad battery alarm in September 2017
    • - Reset bad battery alarm... multiple times over a period of weeks.
    • Replaced battery October 2017
    • Bad battery alarm in (approx) February 2019. Reset alarm
    • April 2019 - alarm has not gone off again.


    I think it is more sophisticated than just a simple timer, but it is prone to false positives. If your bad battery alarm goes off, I'd reset it and see what happens. If it trips again, either get a new battery and re-use the "bad" one for a burglar alarm backup or something not as critical, or if you don't actually need the battery backup, just disconnect it.

    The battery that my NBN power supply repeatedly rejected as "bad" back in September 2017 is still going strong in a small APC UPS.

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    Well it seems my theory is looking a little shaky as the alarm came up this time at midnight on 30th August so not a perfect number of months or even a nice round number of days this time, but at least it was in the first minutes of 1/9 so can't rule out a calendar based system getting it time off the NBN network.

    Simply disconnected the battery for 30 seconds then re-connected it (to imitate replacement being fitted) which reset the alarm to see if it's really based on battery condition or just a timer. Got the spare on float charge out in the shed just in case.

    Must look into what's involved in doing away with the battery backup altogether - the non-backup installation has the power supply in the main NTD box and although there's an empty spot for it in my box, I need to know whether the supply in the battery box can just be relocated to the main box or do I need to purchase another power supply. Another option would be to simply remove the battery and kill the alarm beeper (a bit too intrusive I think) because I found the battery alarm 'silence' button only stops the audible alarm for about 24 hours.

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    If you hold the alarm silence button in for 15 seconds (I think it beeps at 2 seconds, then again after 15 seconds and then you let go of the button) it silences the alarm permanently.

    You can just disconnect the battery, but I think if the power fails, the whole thing resets and comes back up with the alarm enabled.

    The instructions are here:

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    Quote Originally Posted by shred View Post
    If you hold the alarm silence button in for 15 seconds (I think it beeps at 2 seconds, then again after 15 seconds and then you let go of the button) it silences the alarm permanently.

    You can just disconnect the battery, but I think if the power fails, the whole thing resets and comes back up with the alarm enabled.

    The instructions are here:
    I have to hold it for 40 seconds, then it is permanently disabled.

    Battery fail signal annoyance started less than a year after my Fibre was installed which was still under Labor proper NBN which has otherwise worked flawless all the years.
    Battery has been working fine all the time too but if there is a power failure more than an hour or two the silencer is reset.
    These days I don't get power failures anymore because I have off-grid with auto transfer, so for all I know the SLA could be turned to dust.
    Last edited by Uncle Fester; 05-09-19 at 09:22 PM.
    This era of thoughtless consumption must end so we can encourage a world of creative geniuses rather than consumer idiots.


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    The (apparent) best info I could get is to simply disconnect the battery and everything will work as per normal and without alarms with the NTD running off the power supply in the battery box. Next time I get the 'beeps' I might give that a go but my last 'reset' is still working perfectly so far.

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