Yeah, a cap might work although sounds like the charger would view that as a 
bad battery (ie too short a lifetime). I may throw my old battery in and take 
current data for 24hours to see what it does and get an idea of how it monitors 
battery health.

The box works fine without the battery, it just beeps every 10 min or so. Ok 
for me since it is buried in my basement; not ideal for apartment dwellers.

Andy

Sent from my phone using voice-recognition software and/or clumsy thumbs, 
please forgive any typos.

On May 24, 2015, at 5:57 AM, William Wilson 
<[email protected]<mailto:[email protected]>> wrote:

I've been using "supercaps" (in series of 5) to replace (12v) batteries a lot, 
or as "ad-hoc UPS" inline with any device's 12v power supply... like modems 
without a battery slot. Anywhere that really fast charging may be needed and 
amp draw of the device is fairly low. Maxwell brand is cheapest I've seen 
without wating for shipping from china.

connected to an actual charging circuit, depending on the type of charger it 
may not work (had problem with some lithium chargers)

that said, I think I remember seeing a few models of home internet box that 
actually ran fine with the battery removed.


On Sat, May 23, 2015 at 6:02 PM, Jerry Biehler 
<[email protected]<mailto:[email protected]>> wrote:
They might do it how other UPS units do it, they switch the device over to the 
battery to run off it and watch the voltage drop. If it drops too fast the 
battery is bad.

-Jerry

On May 23, 2015, at 5:55 PM, Dawes, Andrew M. 
<[email protected]<mailto:[email protected]>> wrote:

Now my curiosity is piqued beyond just stopping the beep… how would a circuit 
tell between a battery and a voltage source like a large capacitor? Perhaps 
measure a few points of the discharge curve or something clever like that?

On May 23, 2015, at 4:53 PM, Jerry Biehler 
<[email protected]<mailto:[email protected]>> wrote:

Not sure, it seems on mine it could actually detect a battery that was not so 
hot even though it had a full charge. After a few days it would start beeping 
at me again. And for $10 you really cant mess around with tricking the system.

-Jerry

On May 23, 2015, at 4:35 PM, Jason Barnett 
<[email protected]<mailto:[email protected]>> wrote:

You could try throwing a capacitor in place of the battery. It won't help in 
case of a power outage, but neither will a bad battery...


On Sat, May 23, 2015, 12:19 PM Jerry Biehler 
<[email protected]<mailto:[email protected]>> wrote:
No, assuming the battery charger is even a remotely recent design it is 
measuring the voltage of the battery so you would have to have something there 
for it to measure. And I am pretty sure these chargers are actually pretty 
smart. I have one of these fios boxes too.

On Saturday, May 23, 2015, Dawes, Andrew M. 
<[email protected]<mailto:[email protected]>> wrote:
You would have to fake out the battery charger into thinking it is at voltage.
Yes, so I guess my question was: would a zener diode rated at the battery 
voltage do that, or does it depend on the implementation of the charger?

They have tested good used batteries that will fit at surplusgizmos for $10.
Good to know, thanks!

-Andy



On May 23, 2015, at 11:29 AM, Dawes, Andrew M. 
<[email protected]<mailto:[email protected]>> wrote:

I have a battery backup system as part of my Fiber-to-the-home service from a 
certain regional telecom provider. The battery for this system is a 12V sealed 
lead-acid battery (not unlike a golf cart or scooter battery). The trouble is 
that there is a system alarm when the battery “wears out” and needs to be 
replaced — it’s been beeping every 8-9 minutes for the past few months. I’m not 
really interested in consuming another battery for no real reason (I don’t need 
backup because if the power is out at my house I have no need for internet 
access). That said, I’m thinking of a non-destructive way to trick the 
charger/alarm circuit into thinking it has a fully-charged, new & happy 12V 
battery.

I don’t know much about lead-acid charger circuits but I suspect some sort of 
current-limited voltage-regulated supply that alarms when the battery no longer 
holds 11V or some other specified threshold.

Would a simple 12V zener diode work, or would a charge circuit just dump a 
wasteful amount of current into the diode? Perhaps a 13V zener so that no 
current even flows? I have easy access to the battery terminals, and medium 
access to the rest of the circuit.

I’m ok with mangling the alarm itself, but I’d prefer a nice “plug-n-play” 
solution since I know at least three friends in a similar situation who aren’t 
as destructive.

-Andy



--
Andrew M.C. Dawes
Associate Professor of Physics
Pacific University
amcdawes.com<http://amcdawes.com>

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Pacific University
amcdawes.com<http://amcdawes.com>

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Andrew M.C. Dawes
Associate Professor of Physics
Pacific University
amcdawes.com<http://amcdawes.com>

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