2 V VRLA batteries for telecom towers, exchanges and UPS strings
A telecom or UPS battery string built from 2 V VRLA cells is sized in four steps: fix the cell count (24 cells for a −48 V DC plant; for a UPS, the count in the maker’s manual), convert the load to amps at that voltage, multiply by the autonomy hours, and choose the cell whose capacity at that discharge rate covers the result with a margin for ageing. Fullriver HGXL 2 V stationary AGM cells publish capacity at the 1, 3, 5 and 10 hour rates from 100 to 3000 Ah, so the last step is a table look-up. The 2 V stationary batteries page has the series overview and the หมวดหมู่ the full range.
Standby duty floats for years and discharges for a few hours a year, which rewards long float life (Fullriver’s design life figure for HGXL is 20 years in float service at 25 °C), low internal resistance so the string delivers full current the instant the mains drops, and single-cell construction so every cell can be measured, trended and replaced on its own. The cells are sealed, valve-regulated and maintenance-free with no free acid, so they mount in any orientation and suit unattended cabinets. Telecom engineers say VRLA, solar engineers say AGM; here the words describe the same cell. If the chemistry is still open, see the comparison guide.
ในหน้านี้
- −48 V telecom DC plant strings: 24 cells
- UPS DC-bus strings: the cell count follows the UPS
- Sizing for autonomy: the 1, 3, 5 and 10 hour rates
- Hybrid solar-diesel BTS sites
- Cabinet and rack fit: HGXL dimensions, 100 to 600 Ah
- Float duty and monitoring
- Replacement planning
- Utilities, rail and switchgear standby
- คำถามที่พบบ่อย
- Get a sized quote
−48 V telecom DC plant strings: 24 cells
The telecom DC plant is nominally 48 V with the positive pole earthed, hence −48 V. The battery does not care about the sign: the string is 24 cells of 2 V in series, exactly as in the คู่มือแบตเตอรี่ชุด 48 V. String Ah equals cell Ah and nominal energy is 48 × Ah ÷ 1000 kWh, so 24 × HGXL500-2 is 500 Ah and 24 kWh at the 10 hour rate.
Fullriver specifies float at 2.23–2.25 V per cell at 20–25 °C, so a 24-cell string floats at 53.5–54.0 V. Cycle or boost charge is 2.30–2.35 V per cell, or 55.2–56.4 V, applied after a deep discharge. Temperature compensation is −3 mV per °C per cell, so a shelter at 35 °C floats 30 mV per cell lower: 52.8–53.3 V for the string. Where two strings share a bus, keep both to the same model, age and cable length and fuse each separately.
UPS DC-bus strings: the cell count follows the UPS
A UPS string is defined by the UPS, not the battery. Each UPS maker fixes a nominal DC bus voltage, a float voltage and an end-of-discharge voltage, and the installation manual states the number of 2 V cells or 12 V blocks per string that matches them. Use that number. The only maths needed is the series rule: cells = nominal bus voltage ÷ 2, and each 12 V block is six 2 V cells. The common DC buses therefore work out at 6, 12, 24, 55 and 110 cells for 12, 24, 48, 110 and 220 V respectively, and larger three-phase buses follow the same 2 V steps.
The end-of-discharge voltage matters as much as the count: capacity at any rate is published to a stated end voltage per cell, so check the UPS figure is at or below the one the capacity table is quoted to; send us the UPS model and manual page and we check it against Fullriver’s discharge data. Because the inverter sits between battery and load, battery amps = AC kW ÷ inverter efficiency (from the UPS maker’s data) × 1000 ÷ nominal string voltage. Data-centre strings with autonomy measured in minutes are the niche thin-plate pure-lead (TPPL) cells are marketed for; where the runtime is an hour or more, as at exchanges, hospitals and control rooms with a generator behind the battery, a stationary AGM cell sized on its C1 to C10 figures is the economical answer and outlasts several generations of the equipment it protects.
Sizing for autonomy: the 1, 3, 5 and 10 hour rates
A lead-acid cell delivers fewer amp-hours the faster it is discharged (Peukert’s equation), which is why a 500 Ah cell at the 10 hour rate is a 300 Ah cell at the 1 hour rate. Fullriver publishes HGXL at four rates, so you size at the autonomy you need.
| โมเดล | C10 (Ah) | C5 (Ah) | C3 (Ah) | C1 (Ah) | Current at C10 / C1 (A) |
|---|---|---|---|---|---|
| HGXL100-2 | 100 | 85 | 75 | 60 | 10 / 60 |
| HGXL150-2 | 150 | 127.5 | 112.5 | 90 | 15 / 90 |
| HGXL200-2 | 200 | 170 | 150 | 110 | 20 / 110 |
| HGXL300-2 | 300 | 255 | 225 | 165 | 30 / 165 |
| HGXL400-2 | 400 | 340 | 300 | 220 | 40 / 220 |
| HGXL500-2 | 500 | 425 | 375 | 300 | 50 / 300 |
| HGXL600-2 | 600 | 510 | 450 | 330 | 60 / 330 |
| HGXL800-2 | 800 | 680 | 600 | 480 | 80 / 480 |
| HGXL1000-2 | 1000 | 850 | 750 | 600 | 100 / 600 |
| HGXL1600-2 | 1600 | 1360 | 1200 | 960 | 160 / 960 |
| HGXL2000-2 | 2000 | 1700 | 1500 | 1200 | 200 / 1200 |
| HGXL3000-2 | 3000 | 2550 | 2250 | 1800 | 300 / 1800 |
Worked example: a −48 V site on HGXL500-2
Take a base station with a steady 2.4 kW DC load on a −48 V plant: 50 A at 48 V nominal. One 24-cell string of HGXL500-2 supports, before design margins:
- 10 hours: 500 Ah ÷ 10 h = 50 A, or 2.4 kW at 48 V, the full site load.
- 5 hours: 425 Ah ÷ 5 h = 85 A, about 4.1 kW.
- 3 hours: 375 Ah ÷ 3 h = 125 A, or 6.0 kW.
- 1 hour: 300 Ah ÷ 1 h = 300 A, or 14.4 kW.
Working forwards from the load: 50 A for 10 hours is 500 Ah at the 10 hour rate, which points straight at the HGXL500-2; for 5 hours, 250 Ah at the 5 hour rate is covered by the HGXL300-2 (255 Ah at C5). Those are new-battery figures. IEEE 485, the stationary battery sizing standard, applies an ageing factor (1.25, corresponding to replacement at 80 % of rated capacity) plus a design margin so the string still meets the duty at end of life. With the ageing factor the 10 hour case becomes 625 Ah, moving the choice to the HGXL800-2. Tell us whether the autonomy is a minimum at end of life or a target at installation and we size to it; the เครื่องมือคำนวณแบตเตอรี่สำรอง does the Ah-to-model step.
Hybrid solar-diesel BTS sites
On an off-grid or bad-grid tower the battery is both the standby reserve and the daily buffer that lets the generator run a few hours instead of all day. That is real cycling, so the string is sized on the daily discharge as well as the outage case, charged at 2.30–2.35 V per cell (55.2–56.4 V for 24 cells) with temperature compensation, and returned to float once full. A shallow daily cycle on a large cell gives the longest service life, so hybrid sites usually specify a bigger cell than the autonomy sum alone suggests. Fullriver’s maximum charge current is 20 % of C10 (100 A for the HGXL500-2), which sets the generator and array sizing. We size the string and the charging together, and supply KISAE chargers และ อินเวอร์เตอร์-ชาร์จเจอร์ ด้วย temperature sensor for smaller sites; see the charging guide และ tropical climate guide.
Cabinet and rack fit: HGXL dimensions, 100 to 600 Ah
The HGXL sizes most used in telecom and UPS strings fall into two case families: the 100 and 150 Ah cells stand 206 mm high (229 mm over terminals), and the 200 to 600 Ah cells share a 330 mm case and 365–367 mm total height, so one rack takes any cell from 200 to 600 Ah.
| โมเดล | C10 (Ah) | ขนาดกล่อง (ยาว × กว้าง × สูง) (มม.) | Total height (mm) | Weight (kg) | ขั้ว | 24-cell string (kg) | Nominal kWh at 48 V |
|---|---|---|---|---|---|---|---|
| HGXL100-2 | 100 | 172 × 72 × 206 | 229 | 6.6 | F7 | 158 | 4.8 |
| HGXL150-2 | 150 | 176 × 102 × 206 | 228 | 9.2 | เอ็ม8 | 221 | 7.2 |
| HGXL200-2 | 200 | 172 × 110 × 330 | 365 | 16 | เอ็ม8 | 384 | 9.6 |
| HGXL300-2 | 300 | 172 × 150 × 330 | 365 | 22.6 | เอ็ม8 | 542 | 14.4 |
| HGXL400-2 | 400 | 211 × 175 × 330 | 367 | 32.5 | เอ็ม8 | 780 | 19.2 |
| HGXL500-2 | 500 | 241 × 172 × 330 | 365 | 37.2 | เอ็ม8 | 893 | 24.0 |
| HGXL600-2 | 600 | 301 × 175 × 330 | 365 | 45 | เอ็ม8 | 1080 | 28.8 |
To lay out a string, multiply the cell footprint by the count and add the rack maker’s clearance for links and airflow: 24 HGXL500-2 cells occupy just under 1.0 m² of cell footprint. With no free acid, cells may be mounted on their side where a shallow cabinet demands it. Check floor loading against the string weight column.
Float duty and monitoring
Float voltage and room temperature decide how much of the 20-year design life you collect. Hold 2.23–2.25 V per cell at 20–25 °C, compensate at −3 mV per °C per cell as the room warms, and keep the shelter ventilated; the rule of thumb published by lead-acid manufacturers is that float life roughly halves for every 10 °C above 25 °C, so every degree removed from a Thai battery room buys life back. Record cell float voltages, string current and cell temperature on the schedule IEEE 1188 or your own maintenance standard sets. Fullriver publishes the internal resistance of each size (0.30 mΩ for the HGXL500-2), giving a baseline for trending: a cell whose resistance drifts up against its neighbours is flagged years before it affects the string. A periodic discharge test confirms the autonomy, and a cell-level monitoring system turns all of this into an alarm on the NOC screen instead of a site visit.
Replacement planning
Plan replacement on measured capacity, not the calendar. The practice behind the IEEE 485 ageing factor is to replace a stationary string when a discharge test shows 80 % of rated capacity, and trending data tells you well in advance when that is approaching. Renew the complete string at that point so that every cell starts its next 20-year design life together and the autonomy is restored in full; on a live site the new string goes onto the bus before the old one is isolated, so there is no downtime. The HGXL200-2 and HGXL400-2 are priced on the site and the rest of the range is supplied to order from Fullriver, so tell us the replacement year and we quote with the lead time. Stock and support are in Trang, with Thailand-wide delivery and worldwide freight at cost, invoiced separately.
Utilities, rail and switchgear standby
The same cells serve substation, railway-signalling and switchroom DC systems, powering protection relays, SCADA, communications and breaker tripping and closing coils. These commonly run at 110 V or 220 V DC, which is 55 or 110 cells, floating at 122.7–123.8 V or 245.3–247.5 V at 20–25 °C. The load is a small continuous draw for eight hours or more, punctuated by short high-current pulses when breakers operate, so the high-rate figures matter: a 110 V switchgear string is often built from the 100 to 300 Ah cells, whose C1 figures show the reserve left for a sequence of trips at the end of a long outage. Lineside signalling sites are unattended, where a sealed cell with a long float life removes visits. We prepare the IEEE 485 sizing sheet and dimensional drawing for tenders on request.
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What batteries are used in telecom towers?
Most towers and exchanges run a −48 V DC plant backed by 24 sealed lead-acid (VRLA) cells of 2 V in series. The 2 V stationary AGM cell is the standard for exchanges and larger towers because it floats for many years, delivers high current the moment the mains fails and lets each cell be monitored individually. Sizes from 100 to 600 Ah cover most tower strings.
How do you size a UPS battery bank?
Take the cells per string from the UPS maker’s manual, convert the AC load to battery current (kW ÷ inverter efficiency × 1000 ÷ string voltage), multiply by the autonomy in hours to get the Ah needed at that rate, apply the IEEE 485 ageing factor and a design margin, and choose the cell whose published capacity at that rate meets the result, checking the UPS end-of-discharge voltage against the one the capacity figure is quoted to.
How long do UPS batteries last and when should they be replaced?
Fullriver’s design life figure for the HGXL series is 20 years in float service at 25 °C. Service life depends on float voltage, temperature and cycling; a cool, correctly compensated room collects most of it. Replace on measured capacity rather than age: the accepted practice is to replace the complete string when a discharge test shows 80 % of rated capacity.
What is the difference between UPS batteries and solar batteries?
The cell can be the same; the duty differs. A UPS or telecom battery floats at 2.23–2.25 V per cell almost all its life and is sized on capacity at a fixed autonomy, so the 1 to 10 hour rates and float life matter most. A solar battery cycles daily, is charged at 2.30–2.35 V per cell and is sized on daily energy, depth of discharge and cycle life. A stationary AGM cell such as HGXL is rated for both.
Can VRLA batteries be installed on their side or in a cabinet?
Yes. HGXL cells are sealed and valve-regulated with the electrolyte held in the glass mat, so there is no free acid and Fullriver rates them for mounting in any orientation, including enclosed cabinets and racks. Provide the ventilation the cabinet maker specifies, keep cells out of direct sun, fit the charger’s temperature probe to a cell, and check floor loading against the string weight table above.
Get a sized quote
Tell us the string voltage, the DC or UPS load, the autonomy you need and the site, and we will size the string, rack, links and charging and quote genuine Fullriver HGXL cells with the current lead time. For tenders we add the sizing sheet and dimensional drawing. Send us the UPS or plant details, or run a first pass on the เครื่องมือคำนวณแบตเตอรี่สำรอง.
