FiOS SFH ONT 612A SLA battery replacement with Lifepo4

[Xringer]

I was going to buy another SLA battery for my Fios optical fiber box.
When I saw my order history, I realized that I've spent over $100 since 2013 on these SLA batteries. Last month we took a pile of them to be recycled.
I've heard the 612A ONT runs periodic load tests on it's back-up battery before deciding to start that annoying Warning Beeper.
That's when I remove the SLA battery, stick in another used SLA battery.
It's typically a few months to a year before the used SLA batteries give up.
The other day, my last (used) spare would only charge to 9V..
So, when I saw a cool Ampere-Time "drop in", on sale for about the same price as the SLA batteries I had been buying.
I decided to try one! At first the FIOS charger warmed up(90F), but cooled off(72F) within a few hours. It's fully charged.
Yesterday, during charging, I unplugged the 120vac for about an hour to see if there was any failure because of the 6 amp limit on battery output. No problems seen.
The charger & Lifepo4 terminal connectors readings:
2-24-22 13.96 Vdc
2-25-22 13.98 Vdc
2-26-22 14.00 Vdc

Since that's lower than the recommended Charge Voltage: 14.6±0.2V
I think this new battery will only charge up to 80 or 90 percent of capacity.
Which means the life span will be longer.?.

I plan to monitor the voltage to see if there's any variation, perform random 'grid-down' test and post about any problems.

So far, I'm liking this experiment. Since I'm 76, this might be the last FIOS battery I ever change! If it fails in some non-self-destucting way, I'll use the battery in my old hardwired home alarm system.. It's SLA is about aged out.



FiOS SFH ONT 612A SLA battery replacement with Lifepo4 from Amazon.
WAS On sale for $25.49" Ampere Time-LiFePO4 12V 6Ah"
Nominal Voltage: 12.8V
Nominal Capacity: 6Ah 0.2C
Energy: 76.8Wh
Charge Voltage: 14.6±0.2V
Charger Current: 1.2A
Max. Charge Current: 3A
Discharge Current: 1.2A
Max. Continuous Current: 6A
Max. Pulse Current: 20A(＜3S)
Discharge Cut-off Voltage: 10.0V
Cell & Method: IFR32700 N60, 4S1P
*** Did not find Over-Voltage Cut-Off.!. (to prevent over-charge)
https://youtu.be/DYfS2ydD-1Y
Charge & discharge setup video 30 seconds.

[NiHaoMike]

Might it make more sense to fit a PoE adapter in the box and power it from the same backup power source that supplies the rest of the critical equipment in the network? (That's what I did for the core switch in my network, the location makes it inconvenient to fit a backup battery. I powered it using PoE from the server room.)

[Xringer]

Originally Posted by NiHaoMike

Might it make more sense to fit a PoE adapter in the box and power it from the same backup power source that supplies the rest of the critical equipment in the network? (That's what I did for the core switch in my network, the location makes it inconvenient to fit a backup battery. I powered it using PoE from the server room.)

My home 48v back-up power system is manually operated. It's almost never turned on. I run it to test the system when there's a lot of sun available to recharge it.

The 12v battery in the ONT is to provide full power to the ONT for a very short grid-failure. After a few minutes, (w/o grid) it will shut off power to the circuits that provide signal data to the Fios Router and our Cable TV STB. (Power Conservation Mode) When those two ONT devices aren't using power, the ONT 12Vdc battery can still provide our ONT landline phone service for several hours. The landline is the main reason for the battery.

When there is a grid failure that lasts more than a few minutes, we will turn on the 48v inverter, and 120vac is provided to the outlets in my office, so the PC and Fios router can be used. Plus power outlets in the basement will provide 120vac power to the Fios ONT unit/charger.
120vac Power outlets for some lighting, the basement freezer, and the sump pumps in the basement are also fed by the back-up 48v power inverter system.
I'm happy with this setup and I believe the $25.49 "drop-in" Ampere-Time LiFePO4 battery is a good investment. IF it keeps working for 10 years!