C7100V Battery LED flashing

[Mike-48]

I have this (Comcast-specific) cable modem & have disabled the router function, as I'm using it with my existing ASUS wireless router. Because I'm not using the Netgear's router function, I can't simply log into it to check the battery function. (Or is there a way I don't know?)

There is a battery installed, and the battery LED is flashing. The manual doesn't have any information on this. What does it mean? What should I do?

[Mike-48 · Accepted solution]

I remembered that with this modem, no changes work unless it's rebooted. (One reason I'm using it in Bridge mode). I rebooted from my Comcast page, and then I changed the password and logged in successfully, after only 2 or 3 tries. All that to ascertain that the battery status is "Bad."

Which I could have guessed, had I checked Amazon for the battery and read the long list of battery failures -- no other brand for the battery than Netgear.

I'm removing the battery and plugging the C7100V into a UPS. Not the ideal solution, but a UPS with high capacity will give some talk time if needed.

I would not recommend this device to anyone. Unfortunately, it is one of two voice modems approved for Comcast that will handle their higher speed options, the other being an Arris that has even worse reviews than this.

[FURRYe38]

Change the modem back to router mode temporarily to see if there is any web page UI for the batter. 

Is there a front LED thats blinking? 

If the modem is in modem mode, then a battery wouldn't be really important or needed. Nothing to save if the modem looses power. 

[antinode]

> Because I'm not using the Netgear's router function, I can't simply
> log into it to check the battery function. (Or is there a way I don't
> know?)

   Visit http://netgear.com/support , put in your model number, and look
for Documentation.  Get the User Manual.  Read.  Look for "Set Up the
Modem Router in Bridge Mode".

      Note: When your modem router is in bridge mode, use
            http://192.168.100.1 to log in to your modem router.

> There is a battery installed, and the battery LED is flashing. The
> manual doesn't have any information on this. [...]

   At which "The manual", exactly, are you looking?  In the C7100V User
Manual, look for the LED descriptions and "battery"?

> If the modem is in modem mode, then a battery wouldn't be really
> important or needed. Nothing to save if the modem [loses] power.

   Yow.  For what does the "V" in "C7100V" stand?  In the C7100V User
Manual, look for "Install an Optional Battery"?

      The battery can give you five hours of additional talk time and
      eight hours of idle time for voice service during a power outage.

   For about the past century, conventional telephone central offices
have supplied the power to make conventional telephones work, typically
including a (large) battery in the system to deal with electric power
failures.  Without that conventional telephone central office (and its
battery power), as with VoIP, some people would like to continue to have
some telephone service during a power failure.  It's not complicated.

[Mike-48]

@antinode: Thank you for the excellent answer. Yes, of course I installed the battery to keep the voice connection alive in time of emergency.

I must have been searching the install guide, not the manual, because as you say, the LED and login information is there in the manual.

However when I tried to login, I ran into a snag.  Every time I connect via http://192.168.100.1, I get a Web page telling me to change the password. I do that, and the modem disconnects. When I reconnect, I get the same Web page telling me to change the password. And so on. It seems to be an endless loop.

What am I missing?

[Mike-48]

I tried to change the password once more, and encountered an additional form of torture from Netgear. After entering the new password and the security questions, I pressed "Apply" and got the following message:

Sorry, your page is expired.
Please click the menu to re-enter the page. 

Of course, there is no menu visible, and refreshing the page brings up the same old screen telling me to change the password.

I miss my Arris. It was a no-drama device. Pity it wasn't DOCSIS 3.

[antinode]

> What am I missing?

   Firmware which works properly?  Not much you can do about that,
however.

   Relatively recently, apparently in an attempt to be helpful, Netgear
has added features like forced-password-change and password-recovery
features to various products.  Investing only a little time in Web or
forum searches should uncover any number of reports of problems with the
implementation of these features.

   I've never touched a C7100V, so I know nothing, but I'd try a
settings reset to put the thing back into modem+router mode, and try to
get past the password stuff in that mode.  And then hope that changing
to modem-only mode didn't spoil it.

   If it didn't cost more than a better device, I'd also report the
problem to actual Netgear support:

      http://support.netgear.com/

[Mike-48 · Accepted solution]

I remembered that with this modem, no changes work unless it's rebooted. (One reason I'm using it in Bridge mode). I rebooted from my Comcast page, and then I changed the password and logged in successfully, after only 2 or 3 tries. All that to ascertain that the battery status is "Bad."

Which I could have guessed, had I checked Amazon for the battery and read the long list of battery failures -- no other brand for the battery than Netgear.

I'm removing the battery and plugging the C7100V into a UPS. Not the ideal solution, but a UPS with high capacity will give some talk time if needed.

I would not recommend this device to anyone. Unfortunately, it is one of two voice modems approved for Comcast that will handle their higher speed options, the other being an Arris that has even worse reviews than this.

[FURRYe38]

Is the batter user replacable? 

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@Mike-48 wrote:

I remembered that with this modem, no changes work unless it's rebooted. (One reason I'm using it in Bridge mode). I rebooted from my Comcast page, and then I changed the password and logged in successfully, after only 2 or 3 tries. All that to ascertain that the battery status is "Bad."

Which I could have guessed, had I checked Amazon for the battery and read the long list of battery failures -- no other brand for the battery than Netgear.

I'm removing the battery and plugging the C7100V into a UPS. Not the ideal solution, but a UPS with high capacity will give some talk time if needed.

I would not recommend this device to anyone. Unfortunately, it is one of two voice modems approved for Comcast that will handle their higher speed options, the other being an Arris that has even worse reviews than this.

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[antinode]

> Is the batter user replacable?

   Yow.  Is the C7100V User Manual invisible, or inaccessible, or what?

> [...] In the C7100V User Manual, look for the LED descriptions and
> "battery"?

   Is that advice confusing?  Your annoying animated icon seems to be
working harder than you are.

[FURRYe38]

https://kb.netgear.com/000038533/How-do-I-install-the-optional-battery-in-my-C7100v-cable-modem-voic...

https://www.amazon.com/Replacement-Battery-NETGEAR-Nighthawk-2200mAh/dp/B07S192NRY

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@Mike-48 wrote:

I remembered that with this modem, no changes work unless it's rebooted. (One reason I'm using it in Bridge mode). I rebooted from my Comcast page, and then I changed the password and logged in successfully, after only 2 or 3 tries. All that to ascertain that the battery status is "Bad."

Which I could have guessed, had I checked Amazon for the battery and read the long list of battery failures -- no other brand for the battery than Netgear.

I'm removing the battery and plugging the C7100V into a UPS. Not the ideal solution, but a UPS with high capacity will give some talk time if needed.

I would not recommend this device to anyone. Unfortunately, it is one of two voice modems approved for Comcast that will handle their higher speed options, the other being an Arris that has even worse reviews than this.

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[Mike-48]

Yes, the battery is replacable, at $40 a pop for something that users report fails rapidly. Mine failed in 18 months, hardly exemplary, but there are reports much shorter.

That's why I'm going for an external UPS.

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@FURRYe38 wrote:

Is the batter user replacable? 

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[antinode]

> That's why I'm going for an external UPS.

   The batteries in those may not last forever, either.

   One more consideration with a normal UPS: For a light load, like a
modem+router, you might get significantly less run time than you might
expect from a simple calculation based on the battery capacity.  UPS
efficiency is typically highest near the maximum rated load.  With a
very light load, the (under-used) inverter circuitry may waste about as
much power as it delivers to the load.  Efficiency-vs-load information
can be hard to find.

[FURRYe38]

Ok, wanted to make sure you got info about replacements. 

Go for what helps you in the best way. UPS is a good thing. 

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@Mike-48 wrote:

Yes, the battery is replacable, at $40 a pop for something that users report fails rapidly. Mine failed in 18 months, hardly exemplary, but there are reports much shorter.

That's why I'm going for an external UPS.

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@FURRYe38 wrote:

Is the batter user replacable? 

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