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What ’ s your FTTH backup battery strategy ?
Lead-acid battery-based UPS systems cost too much and underperform . It ’ s time to talk about lithium-ion , says David Atman ( right ), president , Lindsay Broadband Inc .
Fibre to the home ( FTTH ) is an increasingly viable option for delivering services to new and existing cable TV subscribers . As the numbers have grown , so too has concern about the new demands that FTTH places on network providers , such as ensuring power to the optical network unit ( ONU ).
The challenges posed by potential power outages are compounded by operational limitations of lead-acid based FTTH uninterrupted power supply ( UPS ) systems . An alternative lithium-ion based system enables improved technical operations and much better total cost of ownership .
FTTH and UPS Systems These were once more limited challenges . Because of the resilience of the hybrid fibre / coax ( HFC ) network , the cable industry has for the most part looked to FTTH as a niche play . Standardised in 2010 , the RF over Glass ( RFoG ) network design was seen as a good greenfield solution . However , with a slow economy , for many years there just wasn ’ t much new construction .
Then the economy picked up , creating more greenfield opportunities . In addition , FTTH is gaining support in some quarters for rebuilds . One North American operator , for instance , has announced plans to pull fibre to all of its 8 million subscribers . Whether or when that happens remains to be seen , but momentum for RFoG and passive optical networking ( PON ) is strong all the same . Between September 2016 and September 2017 , new FTTH ‘ homes marketed ’ hit a record 4.4m in the US , according to the Fiber Broadband Association .
With more deployments comes increased attention to the challenges of FTTH . One factor is fibre itself . Subscribers don ’ t necessarily expect other parameters to improve when their data service becomes faster over an existing ( DOCSIS ) infrastructure , but with FTTH , it ’ s different . Once fibre is drawn to the house and an ONU is installed , the game changes .
The baseline expectation is that with fibre
you get faster connection , higher throughput and 24 / 7 service – with no interruptions . If the lights go out , subscribers expect the ONU to stay on . ( Regardless of whether they have back-up power for routers or other CPE devices .)
That ’ s a reasonable expectation . After all , the ONU is a fibre-optic node . It just happens to be at the customer premises . So , it needs backing up . The question is how ?
For most service providers , the ‘ lights-out ’ strategy for FTTH involves on-premises UPS systems that use lead-acid batteries . Yet that ’ s becoming an issue . Service providers that we know have shared several areas of high-level frustration with existing solutions . We hear that :
• They are bulky and hard to work during installation and service calls
• Their battery life and runtime are both too short
• Poor design leads to connectivity problems , and
• Their total cost of ownership is climbing out of control
Adding to the frustration is the impression that these battery-backup UPS systems have failed to modernise . While rechargeable batteries have undergone change in consumer electronics and other innovative applications , the UPS market segment has been less dynamic .
The original rechargeable battery cell , designed more than 150 years ago , used two lead-based sheets ( positive and negative electrodes ), a separating element and a sulphuric electrolyte . In the 1970s came the valve regulated lead-acid ( VRLA ) battery , which sealed the electrolyte in new ways , promised minimal maintenance and enabled operation in any direction . Today ’ s typical FTTH UPS backup battery is VRLA , but that original design remains largely in place .
Lead-acid batteries are well-established and good at delivering high-surge currents , but they have limits . They are too big for small electronics , and while they do well powering automotive starters , they are impractical for powering cars directly . What consumer electronics and electric car manufacturers use instead is the rechargeable lithium-ion battery .
Lithium-ion vs . Lead-acid Lithium-ion technology first emerged in the 1970s and went into production two decades later . Like lead-acid , these batteries also consist of electrodes and an electrolyte , but use lithium instead of lead . In addition to being lightweight , lithium is highly reactive , so it can store a lot of energy . The net outcome is a low-weight battery with high-energy density .
Consumers may be aware of lithium-ion in smartphones or laptops or hybrid cars . They may also recall reports of heat-related failures and recalls . But this powerful technology , which is now subjected to multiple layers of protection in manufacturing , is now impacting more traditional markets , too . Motorcyclists , for example , can switch out a lead-acid for a lithium-ion battery , dropping from 12 pounds to a little more than 2 pounds in the process . The lithium-ion motorcycle battery also comes with a longer warranty , provides more powerful starts , charges faster and has a better discharge rate .
In markets where lead-acid batteries are competitively priced , lithium-ion batteries are more expensive . ( This is not the case in the FTTH UPS market , as we note below .) One reason is that lithium-ion batteries become inert if they are completely discharged and , as a result , require an on-board computer to manage the charging process .
But maybe lithium-ion batteries should command a premium . Consider these advantages :
Weight . Lithium-ion is much lighter than a lead-acid . A standard VLRA battery used by a
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