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fbruno

join:2000-04-06
Berwyn, PA
Reviews:
·QuantumVoice

Using a 17.0Ah battery on FiOS battery backup

I would like to replace the existing 12vdc 7.0 Ah battery on the FiOS BBU unit with a larger 17.0Ah battery. The objective is to have the BBU device maintain a fully charged battery that provides an longer period of POTS service during a power failure.

I have the 17Ah battery available and it is easy to interface the larger battery with the existing 12volt wiring. Naturally, the larger battery will be stored adjacent to the BBU.

My BBU device is the CS36D12V3-T, recently installed after the older unit failed to restart after Hurricane Sandy.

My two questions are:
1. Although I have search and reviewed many of the posts on this and other boards, I remain uncertain if the charging and maintenance circuitry of the BBU device can support the larger battery.
2. With the larger battery can I expect more than a doubling of on-battery operation compared to the 7AH battery?

Thanks for any support and info.



birdfeedr
Premium,MVM
join:2001-08-11
Warwick, RI
kudos:9

For an experiment, I hooked up a 35AH battery. It charges and maintains a charge. On 2 occasions, the replace battery light illuminated and was immediately extinguished when the ONT cycled through a "power failure" of 1 minute duration.

I have not completed duration testing yet.

First run was not as expected and was terminated after a few hours. I evaluated charging and it appeared to be normal, although I'm using new test equipment and need to check calibration before making definitive statements.

My first impression is that the charge circuitry of the BBU is likely optimized for the 7AH battery characteristic. 35AH battery charges at a higher rate, but not certain it is the best charge rate. When I have more time, I will run through a complete cycle and compare 7 with 35. I still think the better solution for a long term outage is an external battery connected to Auxiliary input. Keep external battery ready to go on a separate charger.

Continuing to evaluate.


fbruno

join:2000-04-06
Berwyn, PA
Reviews:
·QuantumVoice

Thank you for the valuable information directly related to my situation.

I'm similarly inclined to believe the charging circuitry is designed to work best with a 7Ah battery. Putting ourselves in the shoes of the designers who made specification decisions years ago, we likely can assume - with confidence - that they did not take into consideration our desire to use larger capacity batteries with their charging system.

Your suggestion to use an independently maintained external battery connected to the AUX port sure solves the problem with minimal fuss. I think I will go that route. Any suggestions on a type of charger for the external battery?

Thanks again, birdfeedr!



brianmcd
Premium
join:2000-09-06
Norristown, PA
reply to fbruno

I would think that it would be even easier to just plug the ONT into a UPS. You can make the UPS as large as you need and it will take care of maintaining its battery. So your ONT Battery should only kick in when the external UPS has run out of juice.



birdfeedr
Premium,MVM
join:2001-08-11
Warwick, RI
kudos:9

Easy, yes. Efficient, no.

When on battery, my ONT draws 10 watts. When the battery is charged, the BBU PS uses 20 watts just to maintain. That's the FiOS equipment. Now add the losses to run and maintain the second UPS.

I'm not disagreeing with your solution, but there's another one (or two or three).

*My* real solution is to use a backup generator to run lots of stuff in my house in the event of a power outage. The experiment with the battery is mostly to expand the list of options.

If I knew a particular battery solution would give me 36 hours of runtime, I can compare it to other solutions that would provide the same. How do I specify a UPS that would give me 30 hours of runtime with a 20W AC load?


BKE

join:2008-01-01
Leesburg, VA

»www.apc.com/products/runtime_for···mily=165



birdfeedr
Premium,MVM
join:2001-08-11
Warwick, RI
kudos:9

Yowza. SMX750 at $429.00, plus at least one additional SMX48RMBP2U battery at $455.00 (Amazon pricing). For that kind of money, I can put up a solar array, PV controller plus battery and take it off the grid.

Only for a SFU with clear shot to the sky.

One more option on the list.



aaronwt
Premium
join:2004-11-07
Woodbridge, VA
reply to birdfeedr

said by birdfeedr:

Easy, yes. Efficient, no.

When on battery, my ONT draws 10 watts. When the battery is charged, the BBU PS uses 20 watts just to maintain. That's the FiOS equipment. Now add the losses to run and maintain the second UPS.

I'm not disagreeing with your solution, but there's another one (or two or three).

*My* real solution is to use a backup generator to run lots of stuff in my house in the event of a power outage. The experiment with the battery is mostly to expand the list of options.

If I knew a particular battery solution would give me 36 hours of runtime, I can compare it to other solutions that would provide the same. How do I specify a UPS that would give me 30 hours of runtime with a 20W AC load?

Running the UPS is minimal cost in the real world. I get 16 to 18 hours of runtime before my ONT has to use it's own BBU. I use a dozen of the APC 1500XS/Back UPs Pro 1500 models with extended runtime batteries for my electronic devices. The extra power use of the UPSs is extremely minimal.

fbruno

join:2000-04-06
Berwyn, PA
Reviews:
·QuantumVoice
reply to birdfeedr

Click for full size
I can only tell you what I know for experience. The attached picture shows the UPS equipment I use to power an ONT, Cisco ASA firewall, NAS device, and wireless access point. (The reason for my original question was to maintain POTS service at my Dad's house.)

When all batteries are installed and healthy, the equipment provides close to 60 hours of backup power. Currently, only the UPS and one external enclosure are populated with batteries, (they get expensive!) Last month, it easily provided 24 hours of power for the ONT and firewall, and access point (I shut down the NAS to conserve power.)

The entire setup is overkill in some respect, as the equipment was originally used in several corporate distribution closets. We used to change the UPS equipment every three years, at the same time when our company refreshed the network switches. They ceased that process when the true costs became evident, (travel, planning, wiring, consultants.)

nyrrule27

join:2007-12-06
Howell, NJ
reply to fbruno

the older batteries are maked 7.2ah but their true capacity are 8ah. all the newer batties they vz gives out are marked with the true ah of 8.0.