FiOS BBU operation [long post]
WARNING. MODIFYING VERIZON'S EQUIPMENT MAY RESULT IN DAMAGE OR INJURY WHICH YOU MAY BE RESPONSIBLE FOR. IF YOU SCREW THINGS UP, IT'S ON YOU, BECAUSE YOU TOOK THE COVER OFF AND STARTED MONKEYING WITH IT. Several people have said "just leave it alone, it's Verizon's property, not yours." And I agree with that concept, almost. So I'll compromise. If I cause a malfunction on my equipment, I will own up to it, and agree to be financially responsible for my actions.
If you don't understand what I just said, stop reading right now. You'll only cause trouble for yourself. If you agree with what I said, continue reading.
The following discussion applies to BBU Model CPL28U12 and ONT Model Tellabs 1600-611. Other models and combinations may not perform the same way. IT SHOULD BE NOTED SERIOUS DAMAGE AND INJURY CAN OCCUR IF POLARITIES ARE REVERSED OR TERMINALS ARE SHORTED ACCIDENTALLY. DO NOT ATTEMPT TO MODIFY VERIZON'S EQUIPMENT UNLESS YOU ARE PREPARED TO PAY FOR CONSEQUENTIAL DAMAGE.
The BBU model CPL28U12 was originally installed during 2006 with the 611 ONT. During that time short duration power outages and utility blips have occurred with no interruption to operation. However, there's the mysterious Auxiliary jack on the side which is marked positive tip and negative ring polarity, as well as the Auxiliary Power LED on the front panel.
While I haven't been affected by a serious outage, I have always wondered if there is an alternative to total service failure after the battery has given its all to the ONT. Further, is it possible to re-configure the ONT to continue to provide video and data services after the standard 5 minute shutdown? Granted, Verizon is concerned that telephone service continue as long as possible during a power outage, so it's clear they chose to maximize telephone operation by turning off lower priority services.
After careful testing, it turns out Auxiliary is not mysterious, it's merely undocumented. Well, not even that, it's merely unpublicized, by Verizon anyway. Even the techs on the road that I've spoken to aren't clued in on its use. APC provides the basic installation and use document here. »www.apcmedia.com/salestools/ASTE···0_EN.pdf
The BBU controls all BBU functions and only reports status to the ONT. The ONT controls its own functions based on the status signals reported. These are two separate components connected only by 12VDC power and 4 status signals plus signal return.
During normal operation OnBattery, ReplaceBattery, BatteryMissing, and LowBattery signals generated by the BBU are held low (not zero). During alarm conditions, the appropriate signals are latched high (about 12V).
When AC power is lost, the OnBattery signal goes high and remains there until AC power is restored. The BatteryPower LED on the BBU lights up solid. The OnBattery signal starts a timer in the ONT which disables video and data services after 5 minutes. Before and after the 5 minute interval the SystemStatus LED on the BBU stays lit, indicating power to the ONT.
LowBattery and BatteryMissing signals are reported to the ONT. Some combination of these are used to illuminate ONT status LEDs, and possibly to be logged in the ONT system log. Neither of these two signals appear to be used for control by the ONT. They are merely status lines.
Maintain Video and Data services
First question: is it possible to provide data and video during battery operation? The answer is yes for this combination BBU/ONT. Other models may not be modifiable.
To maintain video and data during an outage, swap the wires at the BBU terminal block positions labeled OnBattery and BatteryMissing. In my installation, the wire colors are gray and blue respectively, but may vary in other installations. Now, when AC power is lost, it is reported to the ONT as a missing battery. However, if you disconnect the internal BBU battery, it is reported to the ONT as an AC power failure. So, if you keep the internal battery connected, the 5-minute timer is never triggered, therefore video and data continue to stay powered.
It should be noted that in normal operation, as long as AC power is applied, the ONT is powered whether or not the internal battery is connected or in good condition. During modified operation, the battery must be connected and in good condition, otherwise you will lose data and video after 5 minutes. This is important to remember when you (or a Verizon tech) troubleshoots your system. MAKE A LABEL SHOWING CORRECT WIRE COLORS SO YOU CAN RESTORE ORIGINAL CONFIGURATION. REVERT TO ORIGINAL CONFIGURATION WHENEVER YOU TURN MAINTENANCE OF THE ONT OVER TO SOMEONE ELSE.
Power from Internal Battery
Testing of BBU operation during power failure was simulated by pulling the PSU plug from the wall, with two digital multimeters measuring battery voltage and current. Initial measurements showed the power supplied to the ONT was always 0.15V less than the battery voltage through a discharge cycle. Voltage to the ONT is not conditioned or maintained during battery operation. Spec sheets show ONT can operate as low as 10V supply.
During initial test phases, the ONT operated satisfactorily on battery voltage ranging from 12.78V to a low of 11.65V. Current draw from the battery when normally configured was typically 620mA telephone-only idle (after the 5-minute interval), and 730mA telephone-only active. There did not appear to be much difference in current draw if the telephone was off-hook or an incoming call was ringing in. With video and data enabled, current draw was typically 800mA with telephone idle and 900mA with telephone active. It is safe to say the battery will provide 30% longer runtime with video and data disabled.
All tests for battery performance were performed with the video and data circuits enabled during battery operation. Telephone was idle, that is, not off-hook or receiving incoming calls. Power delivered by the battery was fairly consistent through the voltage/current range. Power equals voltage times current. BBU circuitry plus ONT draws about 10 watts from the battery. Compare that with the power draw of the PSU at approximately 20 watts from AC mains when the battery is fully charged.
In the first run with video/data enabled, a reasonably fresh battery (although it was not fully charged) yielded 6 hours runtime with video/data active and silent telephone before reaching BatteryLow status with approximately 11.72V battery.
AC Power Restored
BatteryLow caused repeated beeps, which can be silenced. Discharge test was terminated and AC power restored. Charge current at LowBattery was 285mA, down to 190mA in 10 hours, down to 120mA in 25 hours, which appears to be near the trickle charge current for full charge.
Monitoring charge current shows an apparent heartbeat with 15-second interval, or perhaps 15-second and 45-second alternating interval. Refresh rate on digital multimeter may have obscured the exact timing, but it appears to be similar to other high performance chargers I've seen where charging is interrupted for a very short time while the battery condition is tested.
The lowest charge current observed is 85mA, which denotes the float charge period where the battery alternates between 6 mA discharge and 85mA charge. Length of time for each charge and discharge period varies and is repeated every minute or less. The battery recovers most of its charge in 24 hours, but it takes another 2 days for the discharge time period to be appreciably longer than the charge time period. In this condition, it's safe to say the battery is fully charged.
Internal Battery Capacity
Ordinarily, two lead-acid batteries can be connected in parallel without adverse effects to the batteries. This is commonly done in high capacity DC/AC inverter systems. In such a scenario, it is recommended the batteries be fairly well matched in capacity and age. If one battery has a stronger charge than the other, the weaker battery is charged by the stronger one, and they end up with the same voltage potential, although with some wasted current due to fluctuations in charge levels. If the difference between the two batteries is large, there will be a greater equalization current flow.
I have two 7AH batteries purchased at the same time, and at the same charge level, so I connected them in parallel. The first run did not yield too much additional runtime, but subsequent results confirmed the battery pair was definitely not fully charged. LowBattery status signal went high at 12.01V. ONT operation continued during LowBattery status with the BatteryPower LED flashing, and the SystemStatus LED remaining illuminated. There was an additional 2 hours of runtime before system shutdown at 11.82V battery level.
Pressing the blue Battery Emergency Use button restarted the ONT from the battery pair and operation continued down to 11.65V battery level before discharge test termination.
On restoration of AC power, the battery pair started charging at 385mA current.
OK, Try Again
Runtime results of the 14AH battery combination strongly suggested it was not a good test. After this pair had been charging for a week, I got 13 hours of runtime with the battery voltage down to 12.01V. The test was canceled before LowBattery status signal went high.
On restoration of AC power, the battery pair started charging at 285mA. Monitoring data for a double battery from full charge through discharge back to full charge took 13.25 hours to discharge 10.58 AH, and 68.93 hours to recharge 10.62 AH.
Testing a single, fully charged 7AH battery yielded 7.25 hours runtime before LowBattery status went high. Battery voltage at that point was 11.78V. Pressing the Battery Emergency Use button restarted the ONT which yielded an additional 2.75 hours runtime with battery level at 10.94V before the ONT shut down. Pressing and holding the blue button down forced a restart of the ONT, but releasing the button caused immediate shutdown. The single depleted battery started charging at 420mA.
Comparing the results of charging a single battery versus a battery pair while allowing for environmental temperature variation suggests the charging circuit of the BBU is not affected by battery capacity. Charge current for a 7AH battery is similar to the charge rate for the 14AH battery combination, and appears to be controlled by battery voltage. The larger capacity battery takes longer to charge.
One could make the argument that APC designers balanced a number of factors and probably settled on a single 7AH battery and optimized the charger for that size. So whether you choose to supplement or replace the internal battery for longer runtime, the choice is up to you.
Which leads to question #2: What is the Auxiliary jack used for? Can it be used to power the ONT when the internal battery is depleted? The answer turns out to be yes.
When there is nothing connected to Auxiliary J4, there's approximately 12V level on it, or about 0.52V less than the internal battery voltage. Tip is positive, ring is negative. Someone posted that it might be for Auxiliary power out, but this is not true. There's a momentary interruption on the J4 line with an approximately 7-second interval when there is nothing connected to it. This suggests the BBU is testing the connection for something.
When a 12V battery is connected to J4, the AuxiliaryPower LED on the BBU illuminates, but there is no current draw from the battery nor charge current to it. Remove the battery connected to J4 and the AuxiliaryPower LED extinguishes. The delay between changing the state of the LED is concurrent with the 7-second heartbeat interval.
During a power failure, the internal battery provides 12V to the ONT. At some point, the LowBattery signal occurs but ONT operation continues until the BBU shuts down.
Pressing the blue Battery Emergency Use button will restart emergency power from the internal battery until it's depleted. If there is an Auxiliary battery connected to J4 and the internal battery is depleted, pressing the blue button will start emergency power from J4.
Disconnecting the current emergency power source, whether internal battery or J4, shuts down the BBU. If you want to run power from J4, connect an external battery to it, disconnect the internal battery, then press the blue button.
I have fabricated an adapter cable to connect from an automobile cigarette lighter socket to the BBU Auxiliary J4. Or to a utility power socket on a JumpStart unit. Because of the 7-second test cycle on J4, I think it was designed for battery connection, not power supply connection.
If I were to place a high capacity battery in the system, I would leave the internal battery as-is, maintain the high-capacity battery in a state of readiness, and manually connect it to J4 in a long-term outage. Some would argue manual control is still not an elegant solution.
AGAIN, IF YOU REVERSE THE POLARITY YOU WILL FRY YOUR BBU. DO NOT ATTEMPT ANY MODIFICATION UNLESS YOU ARE READY TO PAY FOR ANY CONSEQUENTIAL DAMAGE.
I think the reason auxiliary battery use is undocumented, is that Verizon's lawyers did not want to deal with a scenario where someone was injured while running their car in a garage with an adapter to power the BBU during an extended power outage.
All of Verizon's early FiOS documentation shows the potential feature, but says it is not available. Current models of BBU/ONTs may not have this feature.
Recently, two subscribers in my area were forced to FiOS for their phone service due to frequent trouble calls. The old copper POTS lines are at least 37,000 feet from the CO. They have received BPON connections and one is installed with an interior ONT/BBU combination as a single unit, the other with an exterior ONT. Both BBUs have an auxiliary jack, so I believe their equipment will operate as described here. I will check their equipment details a little closer, especially as we get into the hurricane season.
[edited to modify and add]Google research on sealed lead acid (SLA) battery charging reveals high performance chargers with 3 stages for charge and maintenance. Sulfation is a battery problem that can result from deep discharge and less than ideal charging, so the charger can have a definite impact of battery life. Some good links on SLA batteries and temporary power -- »www.windsun.com/Batteries/Battery_FAQ.htm, »www.powerstream.com/SLA.htm and »www.marxrv.com/12volt/12volt.htm