Back-UPS 1100 U-LM - Equipment Dropping

[Anonymous user]

Hey folks,

You probably see this alot. I have both my PC and modem power cords connected to my Back-UPS Surge protector+Backup Battery outlets, but whenever I have a power cut my modem drops.

I unplugged my Back-UPS from the wall socket so everything is using power directly from the Backup-UPS, but when I have a power cut, it's still dropping, which is very strange.

I should say that I had to run an extension cord from my Modem > Extension > Back-UPS, but my PC is connected in a similar way as well but it doesn't have the same issue.

That said, my modem is quite a distance away so I'm wondering if that distance is a factor. I have my sensitivity set to high. 

Thanks so much.

[BillP]

Hi,

The voltage may be dropping due to using the extension cord and the UPS switching to the battery. It may be the modem does not like the sinewave output of the Back-UPS or a combination of the two. For more information on the sinewave, see https://www.upsbatterycenter.com/blog/what-is-a-square-wave/

[Anonymous user]

Thanks for your reply. I'm curious as to why the modem would still drop even when the Back-UPS is completely unplugged from the wall and using the battery.

[BillP · Accepted solution]

Hi @Anonymous user,

If the modem will run when the UPS is warm started/running off of battery but drops when there is a cut over from street power to the battery, the issue may be the transfer time. When a Back-UPS switches from street power to the battery, there is a transfer time. Depending on the model and the sensitivity, there can be a 6 to 8 (high sensitivity), 8 – 10 (Medium sensitivity), and 12 - 14 millisecond transfer delay.

[robmir_apc]

There are some ways to solve this at all but unfortunately none of them are cheap.  Here are my two cents idea 

Option 1:  Replace your UPS with a double conversion one, it always will output pure sinusoidal AC and there is not transfer time.

Option 2:  if your modem is powered with  12 volt  DC and you are handy with electronics you could use a 12 volt 18 Amp SLA battery, a smart car battery charger  like the NOCO Genius 10 , a couple of 5 amp  diodes, a automotive 5 amp fuse and it's matching fuse  holder  as  to make a dual  12 volt power supply to keep your modem always powered.    The setup is quite simple:     cut the positive wire of the cable that feed the modem and  connect the side that goes to the modem to both diodes negative side  joined  ( solder them together and protect the joint  with tape or heat shrink tube) . Then solder the positive side of one of the diodes to the positive wire that you cut before which   goes to the modem original transformer ( protect the joint  with tape or shrink tube) .  Hook with   screws and nuts  the NOCO battery charger plugin adapter positive and negative ( it's included in the charger box with the clamp adapter)  to the SLA  Battery. Hook the battery positive through the fuse holder  to the remaining positive diode side. Hook the SLA battery negative to the negative wire of the cable that goes from the original modem power supply to the modem. ( Splice or solder the joint and protect it with tape or heath shrink tube). Double check the installation. Plug the NOCO charger to the connector adapter, then to AC and set it to AGM battery type. Seconds later It should start to charge the battery.  Plug the modem OEM power supply and check if the modem works fine. Unplug it and now insert the 5 amp fuse in the fuse holder and check the router operation. If it's powering fine then you are ready to plug the OEM power supply to the wall and the NOCO AC plug to the UPS  ( it work fine with any UPS). 

With this setup your modem will be always  powered with pure DC and provide you with many hours of un interrupted internet in case there is a long power outrage. 

[Anonymous user]

Thanks a lot. I appreciate the help!